Electrical safety in historic buildings

Jess (00:00:00 - 00:00:13) 

So, without further ado, let me hand over to Caroline Cattini-Dow, who is a Building Services Engineer Team Leader here at Historic England, to introduce the session.  

Caroline (00:00:14 - 00:02:42) 

Thank you, Jess. Good afternoon, everyone, and thank you for joining us today. So, this webinar, which is entitled Electrical Safety in Heritage Buildings, will, as we know, heritage buildings can present several electrical safety challenges. Many can contain ageing wiring systems that could have been altered repeatedly over time. And records can be quite poor. It's quite common in my experience of working in heritage buildings to see electrical services that have remained in use far longer than they should have been. This could be for several reasons. Limited funding to replace them, or because electrical upgrades can be quite tricky to carry out. And this sometimes results in, you might have some partial modifications, temporary solutions, or installations being adapted around the building rather than being fully replaced. Now, this is quite a big subject, and this is our first Technical Tuesday covering this. We've done other stuff to do with electrical services, like some of you might have joined emergency lighting, fire alarms, external lighting, and internal lighting, but we've not covered electrical safety. So, it's our first time. So, in terms of today, what we're going to aim to give you a clearer understanding of is the specific electrical risks commonly found in heritage buildings. We're going to look at your regulatory responsibilities and then move on to best practice approaches for managing and maintaining these systems safely. And we're also going to look at some practical examples, which are always helpful, and real-life issues that we commonly encounter. And then we're going to have plenty of time at the end for your questions and discussion. And as Jess says, just pop your questions in the questions box there. So, before we move on, probably good if I introduce myself. My name's Caroline Cattini-Dow, and I've worked at Historic England and its predecessor English Heritage since 2003. And as Jess said, I'm currently the Principal Engineer and Team Leader for the Building Services Engineering team. And just a little bit on my background. I'm a Chartered Building Services Engineer and a Fellow of the Chartered Institution of Building Services Engineers. And I've got about 35 years' experience as an electrical engineer. And before coming to Historic England, I spent many years in private sector working for both consultants and contractors. And I'm very pleased to say I won't be delivering this webinar alone today, and I'm delighted to be joined by James Kirby. So, James, if you'd like to introduce yourself.  

James (00:02:43 - 00:03:23) 

Hello. Good afternoon, everyone. I'm James Kirby. I'm a Building Services Engineer at English Heritage Trust. English Heritage have guardianship of over 400 unique sites and monuments, and over a million artefacts through England that form the National Heritage Collection. The collection has variety in size and complexity, such as Stonehenge, Dover Castle, wartime tunnels, and Queen Victoria's Osborne, and around 200 free-to-enter sites that could be a monument, burial chamber, conduit house, henge, or even a white horse. I provide building services engineering advice and support to colleagues throughout the organisation. This includes policy and standards development, building services asset condition assessment, and planned maintenance and replacement.  

Caroline (00:03:27 - 00:04:20) 

Thank you, James. So, just as a brief overview of what we're going to be covering today. So, first of all, we'll look at why we need to think about electrical safety and why is it a critical issue for our heritage buildings. What are the common hazards that James and I have come across. We'll look at your legal duties if you're a manager or an owner of these buildings. We'll move on to inspection and testing approaches. Something on fire safety and integration, and reducing that risk. Then operations, maintenance, and safe working practice. Then, as I say, questions. We've got time for questions at the end. Okay. “So, why is electrical safety important…?” Well, actually, it's important in any building, be it old or new. We have to think about it. We need to have these systems that are safe for our occupants, users, and visitors, and don't present a fire risk as well. James, do you want to start us off on one of the biggest issues that we see?  

James (00:04:21 - 00:04:49) 

Yes, certainly. Many historic buildings will still contain older wiring systems, distribution boards, or protective devices that may no longer meet current standards. Over time, insulation deteriorates, connections loosen, and equipment becomes less reliable, increasing the risk of overheating and electrical faults. Installations that are not updated also miss opportunities to modernise to the current regulations, which include improvements to earthing and bonding, lightning and surge protection, and modern protective devices.  

Caroline (00:04:50 - 00:05:22) 

Yeah, it's very true. And as we see, systems are often routed through inaccessible voids. You can have them behind original finishes. And that can make inspection, testing and maintenance, and any repairs we have a lot more challenging. We have concealed cavities, risers, service voids. We also find inadequate compartmentation or fire stopping in the buildings with combustible materials. So, if a fire were to start, it can spread very rapidly through floors and ceilings and walls' voids before it is then detected.  

James (00:05:23 - 00:05:37) 

And often these buildings will have cultural, architectural, and national significance. A fire in an historic building can result not only in risk to life and property, but also the irreversible loss of heritage, architecture, and historically significant materials.  

Caroline (00:05:38 - 00:06:01) 

Yeah, and just thinking on that last point, now this is a bit of your chance for some audience participation, which I know if you've attended Technical Tuesdays we like. So, I want you to think about how many fires in historic buildings or heritage buildings are down to electrical faults. What do you reckon? 4%, 15%, 38%, or 62%? Just your best guess on where you think we are with these.  

Caroline (00:06:03 - 00:06:08) 

So, yeah, how many fires, out of all the fires in buildings, where do you think we are?  

Caroline (00:06:09 - 00:06:09) 

Okay.  

Caroline (00:06:11 - 00:06:22) 

Interesting. So, we've got a lot of people, over half think 62%. No one's thinking it's down at the 4%. Okay. Yeah.  

Caroline (00:06:27 - 00:06:31) 

I think that's everyone voted, isn't it, Jess?  

Jess (00:06:32 - 00:06:32) 

Yeah.  

Caroline (00:06:34 - 00:10:43) 

Okay, so the answer is actually 15%, which, yeah, you might think it was higher, but actually, if you think about all buildings and how many of our historic buildings make up that, it's still quite a fairly sizable amount of those. And where do we get these statistics from? So, the research comes from the National Database of Fires in Heritage Buildings, and they estimated 15% of fires in heritage buildings were of electrical origin. Now, when it says electrical origin, that's not just your fixed wiring systems. That can be, it can be very old and contain obsolete materials like lead or rubber cabling, which you might have seen, which are very, very old. Over time, as we said in the introduction, systems become poorly altered or incorrectly extended. We get circuits that are overloaded, so, you know, plugging in lots of appliances, which then cause overheating and then present a fire risk. We can have damaged or inadequate cable insulation, generally where they've been in for too long. So, you get the live exposed components, maybe combustible materials there as well, placed near electrical equipment that then can ignite from a fire or a fault. And of course, we have defective portable electrical appliances, which can also present fire and a shock hazard as well. So, that's where they tend to see the fires, that 15% of fires from, in our heritage buildings. So, let's move on to have a look at some of the typical hazards that James and I have come across while we've been working. So, I think we'll start off with this fabulous example. And I'm going to add that these pictures are not just from English Heritage Trust estate or from the Historic England estate. These are ones that James and I had for a very, very long time, so don't necessarily make that assumption. So, this is a very old external fuse board, and it was originally used to supply small internal spaces, and it was also using it to, and its outdoor events board as well. So, if you look at that image on the left-hand side, you can see all the fuses in there, and it's got minimal protection. So, from a safety point of view, from coming into contact with live parts when those doors are open, you can be straight onto those live parts, which is not what you want. Modern boards, they include barriers and compartmentation that will prevent that contact with live components. Now, interestingly, this board was left unlocked, and it also contained asbestos. So, those with keen eyes, you might be able to see the image on the right-hand side, that little A with the black background on there, which is a little symbol that says, “Contains asbestos.” And it was identified on the site's asbestos register. But the site actually thought, “Due to its poor condition” cause it looks pretty horrendous, they assumed it was isolated, it wasn't used, but it was actually live, and it was still very much in use. And it was not only accessible to users on the site, but obviously, we also need to think about people potentially breaking into that, intruders, that they could also do themselves some mischief with that as well. Now, I just wanna make this point quite early on in our presentation that, you know, we do advocate at Historic England the reuse of systems, you know, our building services systems. Some of you might have attended our webinars before, like the mechanical services, reusing pipework, radiators, and so forth. Mechanical services, you can do that. Electrical installations, as a rule, generally, you can't, mainly because of safety around reusing them once they reach the end of their serviceable life. So, cable installation would deteriorate over time. And particularly where you've got systems where they've been overloaded, exposed to heat, or they may have experienced faults as well, that increases the risk of failure and fire. Now, the exception to that will be lighting. Lighting, you can rewire, you can reuse, and there are professional companies out there that do a wonderful job of doing that. And we have got a webinar in September about that. So, they can be rewired and safely returned to use. But generally, as a rule, you don't reuse electrical installations.  

James (00:10:45 - 00:11:39) 

So, these are kind of the opposite in a way. These are examples of older electrical equipment that remains in good visual condition, although its location can create risks and maintenance challenges. When replacement is required, access, lifting, and transport may be difficult, particularly in historic buildings where protecting the original fabric and finishes is a key consideration. Any alterations may also require specific permissions or consents. In some historic settings, lower electrical loads can reduce the stress and heat on equipment, helping to extend its lifespan. However, ventilation, ongoing use, and maintenance remain important. Long-serving equipment, such as switchgear and transformers, may require enhanced maintenance, cleaning, including dust removal, and regular testing of transformer oil or synthetic dielectric fluids. The surrounding environment should also always be considered to ensure that the equipment is suitably specified and protected.  

Caroline (00:11:43 - 00:13:01) 

Now, unlike James's previous example, this installation is in very poor condition, which I think is probably quite obvious from the photograph there. And this is what is called an old PILS cable, which is oil impregnated paper insulation, and that's got a lead sheath on there as well. Now, these cables were once highly valued for their moisture resistance. These cables now generally obsolete and they're hazardous. You'll probably see them as your incoming electrical supplies on some of your buildings. Now, in this example, it wasn't an incoming electrical supply; it was actually a sub-main distribution for the site, and it was feeding one of the buildings on that site. And you can see that the image… the lead sheath is cracked, and that's allowed the moisture to ingress into it, and it's rapidly degraded the insulation. And that black residue that you can see down the cast iron pipe is leaking insulation oil. So, here, you've got hazards, which include toxic substances like PCBs in older cables, oils, you've got the exposure to lead, and most importantly, the failure of the insulation, which is there designed to prevent contact with the live parts. Now, remarkably, this cable, this insulation dated back to 1942, and it was still in operation when I discovered it in 2012. So, yes, it was much in need of being replaced.  

James (00:13:03 - 00:13:38) 

Now, within our collection, we have items of historic electrical equipment, including this switchboard at West Park, and a very early fuse board at Osborne House in the middle. Good practice is to remove redundant equipment where it's safe to do so, reducing risks such as toxic fumes from old PVC cabling and simplifying new installations and fire stopping. Where historic equipment is retained, it should be fully disconnected, clearly labelled, and any residual risks managing, including asbestos and PCB-containing oils. In the left-hand image, the oil-filled circuit breaker trucks have been removed, for example, and safely disposed of.  

Caroline (00:13:43 - 00:16:07) 

Alright. This will be probably familiar with quite a lot of people, the extension leads. And they're very common in older buildings, often because there's insufficient power outlets, or you might have temporary equipment such as, you know, if the heating has failed, you sort of plug in the electric heaters and these are brought into use. Now, the key point with these is they are a temporary solution. The problem comes when they become permanent. Because extension leads shouldn't replace an adequate fixed electrical installation where long-term use is needed. Additional fixed sockets should be installed. Mainly because they lack the mechanical protection of a fixed wiring system. Leads run through doorways, under carpets, across walkways, and over time, they can become damaged, exposing the live conductors and increasing fire risk from that. So, if you do have to use them, think about them temporary, carry out regular visual checks for damage, overheating, discoloration, so, if you see any discoloration on the cable or the sockets themselves. And your nose is extremely important with electrical installation. Unusual smells. You can normally smell when there's a problem with an electrical installation. You also see daisy chaining of the extension leads, plugging one into the other. Not really, shouldn't do that at all. That increases the heat build-up, your electrical protection as well. Also, I just wanted to show, you’ve got a couple of images there, a couple of thermal images there that I carried out some experiments a while back around coiled extension leads. Because I do actually see coiled extension leads not because someone's doing some work on a site like drilling or something like that. They're actually there as a solution, which is not good. They should never be left coiled up when under load. When electricity passes through a tightly coiled cable, you get the heat building up and it becomes trapped, causing the cable temperature to rise significantly. So, we carried out some tests. I did one at home with an iron, and you can see the image on the right-hand side, but quickly had to turn it off because it got extremely hot in a very short period of time. But did it with a portable electric heater. Became extremely hot. I mean, we're talking sort of 70, 80. You know, the insulation was starting to melt. Fortunately, we was at a fire station where we do our fire, where we do our, some of our fire training there. But it was interesting, in such a short period of time with a load on there, how quickly that lead heated up and started to fail and potentially could have caused a fire as well.  

James (00:16:10 - 00:17:30) 

Continuing Caroline's comments about extension leads, I would like to reiterate the risks around portable heaters and the care that should be taken connecting these to a suitable power supply. Portable heaters are often used within historic buildings as they can provide local comfort to occupants within an area without conditioning much larger spaces. Care should be taken when selecting and positioning the heater to ensure that it will not pose a risk to building fabric or users, and heaters chosen that do not have access to the internal elements. For this reason, fluid-filled heaters are often popular. Heaters should also be managed carefully in use, for example, not allowing fabric to come into direct contact with them. On a similar topic, batteries and chargers are also used extensively within all types of buildings now, and historic buildings are no exception. As you can imagine, we use them extensively for radios, landscape and garden equipment, audio guides, and specific applications, such as solar voltaic charged car park ticket machines in remote locations. In addition to ensuring that the equipment is used in appropriate manufacturer-recommended charger and dock, consider the location of the equipment and suitable safety and environmental considerations, such as fire, temperature, humidity, and ventilation, as well as planning when the equipment should be charged for safety and operational reasons. Consider the energy use and whether the equipment has to be left in and on standby.  

Caroline (00:17:32 - 00:20:05) 

Yeah, I see we've got a comment in there that someone's seen an extension lead fire and made the point, “Always use the shortest lead that would do the job.” That's quite true. And also, they're trip hazards as well, aren't they? Yeah, very good point. So, fire stopping. So, fire stopping in our buildings is a really tricky one, because we tend to have, we've got existing installations in some really tight voids, so getting in there can be really tricky and trying to do a good job of adequate fire stopping can be really hard. What should not be done is what we've got shown on the left-hand side, squirting loads of the pink fire-rated foam in the hole. Most foams only have test evidence for their use in linear gap seals. And those linear gap seals are usually only sort of 10 to 20mm wide and will certainly not have test evidence to support them for their use in configurations like we've got in this example in the picture on the left. It's a common mistake because they've got fire foam written on them in big letters that they can be used for any fire stopping scenario. They can't. When you read the small print and you're looking at the test scenarios, it isn't suitable. It's not a suitable solution. And the likely outcome, if you, for our example on the left-hand side here, is it's just going to, if there was a fire, it would just melt and fall out around the gaps around the cables. So, it wouldn't help at all. Now, looking at the image on the right-hand side, in a fire scenario, you would see that, so what's been done there, it's a batt and mastic system, and that will have test evidence from the manufacturer supporting this scenario. So, you'll know how long it would last, you know what materials you need to use. Now, the problem you tend to find, this looks like an ideal example, is that the cables and services very rarely installed as neatly as shown in that picture on the right. More commonly, you'll see cables coming from all directions, no supports. You really do need proper supports. They're extremely important, not only for the electrical service, but as a manufacturer of the fire stopping materials will have them used in their test scenarios. And this is the main reason why people opt for the easy approach, the squirty foam, or nothing at all. Just why do we do it? Why do we use, why do we sort of, fire integrity fire stopping. Well, it stops the spread of fire and smoke from for instance, in these examples, these are in switch rooms, from higher risk areas to other parts of the buildings. What you'll also need is you'll need your fire strategy, so you know where the lines of separation are and what the fire separation would be, if it's 30 minutes, 60 minutes, or 90 minutes.  

James (00:20:09 - 00:21:11) 

Now I'll just talk about locations of equipment for a few minutes. Locating equipment inappropriately can cause, for several reasons, additional equipment installed over the years, particularly if redundant equipment is not removed, it can take up significant space in cupboards and risers. In some cases, new equipment can also be much larger than what it replaces to allow for more protective devices, controls, or just space for wiring. Another common issue is changes required as part of the fire strategy or fire risk assessment. In older buildings, particularly if they were constructed before electrification, space is not available for electrical services. In many cases, equipment has been installed near to the main entrance, within a hallway, or a staircase. These tend to present an elevated fire risk and can compromise the means of escape. To address this, one solution is to provide a fire-rated enclosure to the equipment, typically in a sensitive area of the building. This can be practically difficult and challenging to obtain a tech, sorry, obtain consent. Always be mindful of the fire risk assessment and the potential impact that this can have on the building services.  

Caroline (00:21:13 - 00:22:20) 

Yeah, and I suppose another key concern with this one, James, isn't it, is that, if you can see, those with keen eyes can see that they've removed the distribution board doors, and they were removed because this framing in the building for the riser, they wouldn't be able to open the doors to switch off or maintain it. So, they've just actually removed the doors completely, which is not a good idea. The doors are a critical safety feature. They not only prevent contact with the live electrical parts, but in the event of a fault, so the breakers operate, they also prevent any arc flash from coming out of the board, essentially. And we did have one of these in our Swindon office where we had a breaker operate under quite a large fault current, and it was, when you looked at the inside of the distribution board, fortunately enough the door was closed. There was also a fire door on the riser as well. The amount of black scorching on there, you know, if you imagine no door, you've got timber there as well, you know, there's a potential for a fire there as well. So, they should never be removed, and they should always be kept closed and locked. They're there for a reason.  

James (00:22:22 - 00:22:59) 

And to finish with a very common issue and hopefully an easier one to resolve. This is not necessarily a problem specific to historic buildings. All building equipment should be located within a suitable area, adequately protected, and have available access for maintenance, replacement, and in an emergency. Limited space within all types of buildings can make this an issue, but compromising access to equipment or risking damage to equipment can increase the risk and consequences of a fire. Consider how access is managed to rooms containing building services equipment, not only to members of the public or non-authorised persons, but also how the risks can be communicated to building users.  

Caroline (00:23:02 - 00:23:28) 

So, we'll say a bit of audience engagement again. So, having looked at all of our images and looked at some of the installations and the age of them, best guess, how long do you think electrical installations last? What do you think the age of them should be before they should be replaced? So, do you think 10 years, 15 years, 25 years, or 40 years? How long do you think they should last before we replace them?  

Caroline (00:23:33 - 00:23:32) 

Okay.  

Caroline (00:23:38 - 00:23:42) 

25 years is out there. I don't think we've got any more votes coming in.  

Caroline (00:23:45 - 00:24:12) 

This is a very well-informed audience. Excellent. So, yes, 25 years. Yeah, around 25 years. You get slightly longer with armoured cabling. So, that's more like your consumer units, your distribution boards, and accessories, and those types of things, 25 years. Armoured cabling and stuff like that, probably about 30 years. But yeah, excellent. That's really good. So, 25 years. And I think James is going to tell us where we find this information from.  

James (00:24:13 - 00:25:27) 

Yes, thank you, I'm very impressed. So, building services engineers have the Indicative Economic Life Expectancy tool published as part of CIBSE Guide M in 2020. Now, the guide itself was updated in October 2023. And this is hot off the press. The authors have just published the Indicative Economic Life Expectancy Tool this month in June 2026. This can be accessed for free via the CIBSE website. The tables are based on a cross-industry collaboration between Building Engineering Services Association, BESA, and the Royal Institution of Chartered Surveyors, RICS, meaning that they're harmonised across tools such as SFG 20 and the new rules of measurement. The life expectancies are indicative and can be affected by factors such as the environment, use, and maintenance. Therefore, it is usual to monitor equipment condition and maintenance costs throughout the life cycle and adjust the expected life expectancy accordingly. At English Heritage, we use condition surveys to do this, undertaking these on a variable cycle in accordance with the size, age, and condition of the installation. We use the results to influence the frequency of our statutory testing and plan for replacement of equipment.  

Caroline (00:25:33 - 00:33:12) 

So, as building owners and employers, we have a legal duty to ensure the buildings are safe for occupants, employees, visitors. And for workplaces if we start off with workplaces first of all, we've got what's called the Electricity at Work Regulation 1989, and that's under the Health and Safety Work 1974. And what that requires is electrical systems are maintained in a safe condition, and that's under, in the Electricity at Work Regulation 4. And that makes, what it says in there is you need to make regular inspections, testing, and maintenance, and that's mandatory for those installations in those places of work. And the electrical installation, it refers to the fixed wiring system. So, that's your consumer units, distribution boards, lighting sockets, power circuits, but not the portable appliances. That falls under something different. Then if we think about rented properties, you've got the Electrical Safety Standards in Private Rented Sector Regulations that came in in 2020. And again, it’s very similar wording, require the regular inspection and testing. So, we've got this similar theme through there, inspection, testing, and maintaining those systems to keep them safe. Now, compliance is generally achieved by using and if you just see on the image on the right-hand side, that yellow book down the bottom there is what's called the BS 7671, and that's the IET Wiring Regulations. We're up to the 18th edition now. And in there, the key message is that safety requirements don't disappear because it's a heritage building. Sometimes people think, “Oh, it's a heritage building. You know, is there some exception?” There's not. But it may deliver the way in which compliance, we might change how we go about that. But to comply with these regulations, it's carrying out those routine checks, and you undertake what's considered, what's called a periodic inspection and testing. So, EICR, you may have seen that, and we're going to come on to that to explain it. You perform that maintenance where you're required to do so and keep those records up to date of what you're doing as well. So, we're going to look at this EICR that I mentioned in the previous slide. And some of you would be familiar with these. If you look after buildings, you would have seen these before. They're probably quite familiar. So, as I said, it's called the Electrical Installation Condition Report. And it's a formal document, and it will be issued by a qualified electrician, and it will contain the results following their in-depth inspection of a property's electrical installation. It's basically a 4-step approach. They do a visual inspection, so they're looking for obvious signs of damage, poor installation quality, such as cracks and wears and tear on equipment, you might get those on socket outlets and switches, signs of overheating and burning. Then they carry out tests on circuits, and there's several tests they carry out. They'll be looking around the safety of that wiring system, working out correctly if this is installed correctly, and it's working correctly, and it remains safe to use. They'll ensure that all the wires are properly connected, there are no broken connections hidden within the system. They'll be looking at the protective covering around the wires, that insulation, to make sure it's in good condition, is not at risk of causing an electric shock or any faults. They'll confirm that the system has been wired correctly, that sockets and switch and safety devices operate as they're intended to do, and verify that any electrical faults occur, the power will switch off quickly enough to prevent injury or fire. And someone's just said, “How is the ESR different from a fixed wiring test?” It's not. It's the same thing. That's just the official name. People just go “fixed wiring test.” It's the same. It's the Electrical Installation Condition Report. So, I just thought I’d quickly answer that question. And the final step for after they've done the inspection, so the testing of all of that, the homeowner, landlord, or business will receive a full report on the electrical safety status of their home or property, and it will list any of the electrical faults diagnosed and their classification codes they have, and we'll come on to that, what that means, and the recommendations of how you go about fixing them. So, if we just look at the front page on the EICR on the right-hand side, just make sure I click on so you can see all these. Right. So, you've got the date of the test. It will give the electrician will have an estimation on the age of it. Sometimes that could be a little bit out, but if you've got that information, give it to your electrician. Always good for them to know. And it will say when it was last inspected. It will then say the outcome of the test and inspection and when it should be reinspected. And on this one, if you look down the bottom of that, you'll see that it's got unsatisfactory, and it's saying that you need to test it again in 12 months. So, why on this particular example was it found to be unsatisfactory? So, this is the following pages on from there, and you get these lists of everything they found. And you'll see on this one there's loads of different codes. So, in this case, you'll see on the sheet, you can see some C2s on there, and that's why it was found to be unsatisfactory. If you get C2s or C1s, there'll be the report will come out unsatisfactory. And why is that? So, Code 1 is dangerous, danger present, so they will be rectifying that. That will be immediate action to be taken. C2 is it's potentially dangerous, so emergent, urgent remedial work is needed. And C3, there's some improvement recommendations, so it's not dangerous, but it needs to be improved. And you'll see on there as well there's some FIs, and they're further investigations. So, what they're saying is, “Not sure. Something's wrong here.” I think there was somewhere, it might not be this one, it might be another one I was looking at recently, is they couldn't quite trace out where the circuits were going. So, that's a further investigation, and what that can mean is it can end up a C1, C2, or C3, but at the moment, it's further investigation. So, we had on there as well the different time periods between testing. So, it said on that one, it said 12 months, didn't it, on that particular one? And that was for a non-domestic building. Now, I always hear people go, “Oh, no, it's every 5 years. You have to, you just have to do it every 5 years.” It's not every 5 years. They say 5 years non-domestic, 10 years for domestic. It is not straightforward 5 years and 10 years. James mentioned earlier that the how often you do testing, how often you do inspection, or how often you might do something is a risk assessment depending on the building, depending on what's going on there. So, the environment will play a part, the building use, the occupants. It's a risk assessment. It's not straightforward. And you'll see on this table, and this comes from the IET Guidance Note 3, which is Inspection and Testing. Now, this is part of the table, they've actually since updated this in the 2026 version. They take into account an awful lot more buildings in there and different types of sites and so forth. But you'll see that there's different periods for different sites. So, theatres, we've got 3 years. Fire alarm installations, I mean, you do that every year with your fire alarm system as well. You've got places of public entertainment, that's 3 years as well. So, it's a risk assessment. It isn't a straightforward, “Maximum 5 years,” “Maximum 10 years.” So, I think we've got another poll. Yes, we have. So, I want to give you a scenario. So, if we had a non-domestic timber building with an electrical system in, and that installation was 25 years old, so remember when we said that they needed to replace, which was 25 years for electrical installation, how long would you leave the period between inspection and testing? So, would you leave it, would you do it annually? Would you do it every 2 years, 3 years, or 5 years?  

Caroline (00:33:21 - 00:33:24) 

Yeah. What do you think, James?  

James (00:33:25 - 00:33:30) 

I think there's some very good voting there. I think that's excellent.  

Caroline (00:33:31 - 00:33:31) 

Yeah.  

James (00:33:32 - 00:33:40) 

It's certainly- for an English Heritage property of that description, we'd probably look for an annual inspection.  

Caroline (00:33:41 - 00:33:55) 

Yeah. And actually, the building, the one I showed you, the example was from a timber building. The installation is over 25 years old and they're doing it annually just to keep a good check on that as well. So, yeah, excellent. Good.  

James (00:34:00 - 00:36:09) 

So, thank you, Caroline, for that comprehensive introduction to the EICR. Obviously, we've moved through it pretty quickly, or Caroline's moved through it very quickly, and there's a huge topic there. But as you can imagine, with our varied estate, English Heritage have a site-specific approach to undertaking the EICR. While many of our sites are subject to a 5-yearly test, we increase that frequency where it's required. In addition, and I think these can sometimes get overlooked, we also place a very high importance on the annual routine checks, which are also described in detail within guidance note 3, but there are other things you can do. To supplement but not replace the statutory requirements, there are other procedures and tools that we use to understand the condition of the electrical installation without damaging the historic fabric. These can be operational in nature, such as load assessments, assessing equipment performance and efficiency, environmental and energy consumption monitoring. We use these to confirm that equipment is still operating as well as it can, that environmental conditions are met to develop the plant replacement strategy and support our transition to low-carbon energy use. The data, particularly through our smart energy metering portal, can also be very useful in helping to determine the most cost-effective energy use, supporting operational decisions for the building. We also use a variety of non-intrusive tools such as thermal imaging, endoscopes, and digital surveying, which includes photogrammetry and LiDAR, to understand the buildings and equipment as well as we can. Infrared thermography is a non-contact, non-destructive test method that utilises a thermal imaging camera to detect, display, and record thermal patterns and temperatures across the surface of an object. Where infrared thermography is applied to electrical building services, it can potentially identify defects where they cause or are caused by increased temperature. Applications include electrical distribution equipment, motors and plant control panels, wiring, lighting systems, and small power accessories. A rise in temperature could be the result of a loose connection, a load imbalance, overload, or defective or deteriorated equipment.  

Caroline (00:36:11 - 00:39:06) 

Yeah, so thermal imaging is a fantastic tool, and not just for electrical systems. So, I just want to take you through sort of an example of using the qualitative and quantitative use of thermal imaging. And this is the example. This is an incoming cut-out at a site. So, this is the incoming supply, and you've got the three fuses there. So, first of all, if we look at the image on the left-hand side, the thermal image there, you can see between the three fuses, one's glowing red and the others are blue. And it's like, “Actually, why is this happening?” So, a lot of the time, this could just be an imbalance. If you, that's the first phase on a system, the fuse that's on the left-hand side, and people tend to load it up with much more, it's quite common when you look at electrics. So, you put clamp meter on there and it always tends to be more loaded than the other phases. It could be that. So, it could be that, and you can get a bit more heat there, or it could be something else. It could be a fault. So, that's the qualitative. We're doing a comparison in those, what it visually looks like. So, let's have a look at the quantitative. Let's have a look at the numbers that we're getting for the difference. So, we've got sort of the two blue-coloured fuses. We've got sort of about 20-odd degrees, and the other one's 40. So, it's like, “Okay, this is not too bad.” It's not operating at the reach of its, what it should do, been designed to, like up at 70 degrees or something like that. But it does give you cause for concern, not immediate cause for concern, because it could be just that it is so much more overloaded, which in this case it actually was. It was much more heavily loaded, and it's like, “Actually, we should look at balancing the load better over the- over those three phases as well.” So, that's one example. Let's look at another example where, okay. This is not quite as straightforward as that first one. So, again, this is the incoming supply to a distribution board. And you can see again, so we look at that quality, we're looking at the difference, one glowing yellow there. And if we look at the temperature gauge, it's sort of way over 70 there in temperature. Then we look at the other ones, and it's much, much lower down, so I don't know, mid-20s maybe. So, not only is it operating above the temperature it should be designed to, sort of cables tend to be 70 degrees, it's like way up there. So, that's going to cause deterioration of cable and problem with it. So, yeah, there is something wrong here. It's not just overloaded, and it's also not the first phase, which tends to be overloaded, but you could put a clamp meter and check. But what this is saying to me is, it's like, “Is it a loose connection? Is one of those terminals loose, which can create a build-up?” So, normally you torque tighten them so you know they're nice and tight. If it's loose, if it's worked loose over time, is there an issue with that where we're getting heat build-up there? So, for this one, definitely further investigation, as it's highlighting quite an issue there. But it's a really good tool with electrical installations. But I have to say is make sure, if anyone uses it, switch the power supply off, then take the cover off. You need to do it quite quickly so you've still got that heat there, and then you can put the cover back on and switch the power on if you're doing it.  

James (00:39:09 - 00:40:33) 

So, I'd like to just mention a case study around historic lighting and some of the things that we should think about for these. So, I've included some examples of potential issues that we have with historic lightings that we've seen. Historic light fittings can form a significant part of the collection and require complex conservation well beyond the electrical installation. They typically require a cleaning regime and then periodically more thorough conservation, during which the opportunity can be taken to rewire the luminaire. Issues can arise when the wiring installation is not monitored and rewired for a considerable time, which can happen if the light fitting slips through the gap between the fixed wire testing and the equipment. We also use thermal imaging to assist with the condition monitoring of historic luminaires. The image on the right-hand side is of a cove lighting installation within a beautiful 1930s Art Deco interior. The original curved fluorescent tube is visible, and great care must be taken to protect or remove these carefully due to the mercury content of the lamps. A flexible LED luminaire has been installed within the cove and this works really well. This is a lightweight solution; however, we have encountered situations where heavier lighting fittings have been considered, including for temporary use for filming, which could have exceeded the weight capacity of the plaster cove. One of the most interesting aspects of working with historic buildings are these unusual challenges and things that must be considered.  

Caroline (00:40:34 - 00:40:42) 

That's such an unusual and cool use for thermal imaging. I've not known anyone that's done it with lighting so far. That's a really good application, James.  

James (00:40:45 - 00:41:54) 

Thank you. Taking a risk-assess-based approach helps us to define an appropriate strategy for electrical installations in addition to the building's British Standards. It is important to understand how the building is required to operate in addition to the requirements arising from the fire risk assessment and emergency management arrangements. When considering specific measures, we should consider the following: electrical isolation strategies, zoning, and smart monitoring to allow for faster diagnosis and response; equipment locations, access, and fire protection; cable specification, routing, and protection; how the equipment is required to perform in the event of a fire, including any evacuation or fire suppression systems; what active equipment measures could be taken using technologies such as Arc Fault Detection Devices; Lightning and surge protection (I'll talk about these in a moment); and what fire detection alarm technologies are available, including very low fabric impact systems such as aspirating systems, wireless detection, and beam detectors. The technical guidance section of the Historic England website provides useful information on many of these subjects.  

Caroline (00:41:56 - 00:42:32) 

Thank you for the plug, James, on the HE website. So, taking that risk-based approach, it also reduces the cost associated with changes. So, retrofitting, I know you're going to come on to the Arc Fault Detection Devices as well, so you can look where your risks are and what would you put them in, which I know you're going to come on to. Someone's just picked up on your thermal imaging and how often you might do the surveys. I know we was doing ours with the annual inspection. We was doing it on our older sites. So, where we've got the older installation where there's a greater risk, we was sort of targeting those ones. I don't know if English Heritage do the same type of thing.  

James (00:42:33 - 00:42:50) 

Absolutely. Yeah. Like a lot of things, we take a risk-based approach, and we do, there's quite a few that we do annually. And it can depend on all sorts of things, not just on the installation but also on the type of collection and the type of equipment and its age that we've got there. So, yeah, it can vary quite a lot.  

Caroline (00:42:51 - 00:42:53) 

Yeah, brilliant. Thank you.  

James (00:43:00 - 00:45:18) 

So, I'll finish by briefly mentioning some new technologies that may not be present in older installations, and which should be considered, as they can provide additional protection for the electrical installation in building. Now, these are always provided in addition to the overcurrent protective device, which would typically be a fuse or a circuit breaker. So, first of all, RCDs, Residual Current Devices, are the most common type of additional protection. And these have been described within the Wiring Regulations since the 1980s, although their use has increased through subsequent updates. Being very sensitive devices, they measure in milliamps the difference between the live and neutral conductor current and disconnect the supply rapidly if this exceeds the threshold. The principle being that any current imbalance must be leaking to earth, for example, through the human body. Surge Protection Devices have also been included within the Wiring Regulations for a number of years. However, a simplified risk assessment for when SPDs are required was introduced in the 18th edition in 2018/2019, and this increased their use considerably. SPDs protect against transient overvoltages that typically enter the building via the main electrical supply or other external cabling, such as telephone lines, supplies to other buildings, and external lighting. Overvoltages can be caused in a number of ways, but lightning strikes and distribution network power supply switchings are two of the most common. Arc Fault Detection Devices are a relatively recent technology and were introduced within the 18th edition of the regs, although mention was made within the 17th edition. Subsequent amendments made to the regulations have clarified their potential applications. AFDDs use microprocessors to identify arc faults by analysing an arc's waveform. Arcs can be formed between damaged cables in particular, and high impedance earths that can exist that, while not detected by an overcurrent device, would be detected by an AFDD. These have particular benefit in heritage buildings, particularly those with features such as older wiring, combustible or fire propagating construction, for example, timber or sleeping accommodation. When these first came to the market, they were notable for being relatively expensive and requiring additional space within the distribution board. This has improved over time, but they are more complex than an overcurrent or residual current device.  

Caroline (00:45:22 - 00:48:13) 

Thank you, James. So, just in conclusion so we've got enough time. So, I know we've got quite a lot of questions coming in. So, just key findings. Routine checks and record keeping, which is what we've been saying throughout this. We haven't covered this, but it's a really important one, and I don't think this will be the end of our presentations on this subject, because as I said at the beginning, it's quite a big subject, which I'm sure we can do more about. When you have contractors working on site around electricity, they really do need clear briefings over what they can use, the fragility of site, restricted access, and importance of avoiding that damage, and sort of isolating their electrical supplies and so forth. Managing that temporary power during those renovations. And it needs to be handled really carefully. So, it might be something we do in the future on that one. And as we've said throughout this, and hopefully that's come through, is historic buildings, it's a much more risk-based approach for maintenance. Challenging that standard 5 years, and I know there's some chat in the questions in there. It sounds like some of you always get your EICRs through, and it always says 5 years. Yeah, we get that quite a bit as well. I've seen it far too many times on really aged systems, the cable with, the bad cable, the 1942 installation, that said 5 years and clearly really shouldn't have been 5 years. So, it's those regular checks, good documentation, and challenging that. And really, I think it's come through, heritage buildings are only safe if they're continually managed safely. So, I want to get to the questions because I know we've got not much time left and I want to make sure we do. Just quickly plug on our Technical Conservation Guidance Research, anything to do with websites, publications. If you join the mailing list, you'll get all this information as well. So, I think we're going to come to questions straightaway, Jess. Shall we just get on with those to make sure we've got enough time? So, let's have a look. So, let's have a look at these first ones here. Yeah, that first one around fire spread. Charlie Harrison, let's see if my camera will come on. It might not. I've been having trouble. Oh, there we are. Our fire advisor, there's no requirement at the moment for fires in heritage buildings to be recorded. So, in terms of what did that mean, that 15%? Was it fire spread through other areas and so forth? I don't know. They just actually say it was a fire caused by either wiring or equipment, those particular reasons. It doesn't give out, like, significance as well. So, you wouldn't know the significance of those buildings as well. So, I know he's doing a lot more work, and I think there's some stuff on our pages on that as well. I think, James, this is one on your English Heritage. You showed a nice example, didn't you, of where an electrical installation itself becomes the heritage asset?  

James (00:48:15 - 00:48:17) 

Yes. I'm just trying to spot that. Which one- 

Caroline (00:48:17 - 00:48:23) 

So, someone's asked, “Is there the point where the electrical installation itself becomes the heritage asset?”  

James (00:48:25 - 00:49:21) 

Yes. We, as tend to be, just left in a display situation and we try and obviously keep access to where you can see those as far as possible. We don't have many installations that are operational and live that would be considered heritage now. Our operational ones tend to date back to probably no further than the 1960s, which we keep a close eye on, maybe a bit later than that. But I'm a strong advocate for keeping these things and people being able to see them. You might have spotted that, for the keen-eyed amongst you, I'm at a site called Berwick Barracks today. And I've just been into one of the museums here, and there's a beautiful old telephone switchboard that I think is used every now and again just as a demonstration, and being able to see and enjoy that as just as part of the rest of our heritage is important to me as well.  

Caroline (00:49:22 - 00:50:32) 

And sometimes you see it, don't you? I think it was, I don't know if it's the library in Manchester where the beautiful ornate switch plates on there, which were just lovely. And they, obviously, they weren't used again, and the switches are hidden behind all their wireless systems. And they've just kept them as part of sort of the aesthetic of the building, but they're not actually in use there. And someone's asked, “Is there any specific body or accreditation for finding electrical professionals familiar with historic systems and issues?” There isn't. Most of the, actually all of the, so, like, CIBSE, IET, IMEC, those types of institutions, they don't want to do separate accreditation, and I can kind of understand why, because there isn't building services engineers, you don't tend to do all historic buildings work, and then they've got to manage that system. So, there isn't. At CIBSE, we do have a heritage group, a heritage and retrofit group that James and I are members of. So, if you did have any questions, you can direct, so if you go on CIBSE's website, you can find out more about that. But there isn't a particular body around that. That's, so let's have a look.  

James (00:50:33 - 00:50:36) 

I can pick up the lightning protection if you like.  

Caroline (00:50:36 - 00:50:36) 

Oh, yes, please. 

James (00:50:36 - 00:51:06) 

Because I think that's an interesting one, and it's been something that I get quite often. I touched on surge protection, which is part of lightning protection and part of British Standard for that. But clearly lightning protection is a very important part of many heritage buildings and modern buildings as well. I believe there's quite good guidance on the HE website for that, Caroline, if that's correct.  

Caroline (00:51:06 - 00:51:07) 

There is, yes.  

James (00:51:08 - 00:51:48) 

My own takes on it is what you might often find with lightning protection system is that you have a system that's been installed at some point in the past, and then has been dutifully maintained and certified on an annual basis. But then I think it's always quite important to just take a step back and see whether anything's changed and to see whether you should consider redoing the risk assessment, which may well have changed considerably since the original installation was completed, and just see whether there's any sort of justification to bring it up to a more recent standard of lightning protection because things have changed slightly. So, I hope that answers the question, if tangentially.  

Caroline (00:51:49 - 00:53:02) 

And there's one on here about, this is quite a good one, which, about electricians undertaking ESO. Is it C1, is it a C2, or is it a C3? I was desperately flicking through Guidance Note 3, because Guidance Note 3, which was the yellow document that I, I don't know if I hold up, I don't think you'll be able to see it. No, you can't because I've got a blurred background. Is the inspection document from the IET, and helpfully, they used to list what constitutes a C1, what constitutes a C2, and constitutes a C3. It doesn't appear to be in the same place as what it used to be in, but certainly in the older versions. And it's very helpful, because if you want to challenge your electrician, if they've made loads of C1s and C2s, it's, but it generally is something, I don't know that's easy for a layperson. James and I are both electrical engineers, to sort of challenge that, but there is a helpful, and I will try, I'll probably come back to you on that when I find out where that’s listed. But I think someone's also said NAPIT also does that as well, which is, you're probably quite right there, what is and what's not, which, so NAPIT’s quite a good one. They're a testing body that you can refer to as well. NT do them every 5 years, EICR every 5 years. Okay, I'm not going to comment on particular institute, particular bodies of what they do.  

James (00:53:05 - 00:53:08) 

Shall I just talk about the questions around solar?  

Caroline (00:53:09 - 00:53:10) 

Oh, yes, please, James.  

James (00:53:10 - 00:54:16) 

For a minute, as I touched on it very briefly. The sort of solar and batteries should be carefully considered, would be what I'd say, in terms of historic setting. We do have solar systems on some of our sites at EH, but they tend to be very carefully considered about where the best place to put them is, and I'd imagine that others would have a similar kind of careful process, both in terms of fire risk and the risk to the building, but also in terms of consents and the setting that they're in. There are, we've got examples in the country of some very prominent solar installations, and they do come up quite a lot. Batteries are similar in a way. I think it's considering the risk of having additional equipment and the things that go with it, and the setting of that equipment is important. So, it's unfortunately, it's not a straight yes or no, but it is, I've had some very interesting discussions about where we should or where we think it's not appropriate to put both of those technologies.  

Caroline (00:54:17 - 00:55:40) 

Yeah, I think some people are saying 25 years replacing electrical installation is ideal. Yes, you're right, it is. I think it's one of those ones where, as I said, it's risk-based. 25 years. And the document that James shared is for all building services installations, and, you know, for heating systems, it might say 40 years or something like that, or boilers, it would be obviously a lot less. But it's how they've been maintained throughout the life, the condition of the building. Someone that's an engineer inspecting them and going, “Well, actually, what's the condition of them? How heavily loaded are, what are those signs when we test them? What do we look at when we thermal image them? What do we look at” “Okay, it's 25 years old, but it's in really good condition. It's been really well maintained. It's not overloaded. It's fairly lightly loaded. Do you know what? Let's maybe increase our inspection and testing of them just to keep a check on it, just to see what's going on. And we can just see how often,” if you start getting loads and loads of faults where it's dropping off a cliff, the amount of remedial work you have to do and repairs you have to do, it's telling you something: your installation's starting to fail. Like with any building service system, it's costing you more to maintain it and it's becoming a greater risk. But yeah, I take your point is it's an indicative number, like what James said. You know, think about in 25 years, when you're planning for that, how often you might need to do that.  

James (00:55:41 - 00:55:44) 

I can answer the question for English Heritage as well that was posed.  

Caroline (00:55:44 - 00:55:45) 

Yeah, go ahead. 

James (00:55:46 - 00:56:28) 

We have some incredibly old electrical installations that are still operational, but they're very carefully monitored to make sure that their condition is good. There's a type of wiring that many of you will be familiar with called MICC, or Mineral Insulated Copper Conductor, that is highly moisture resistant, sorry, highly robust and fire resistant, but can succumb to moisture over time. And if you don't monitor that, gradually it can deteriorate. But it lasts for an awfully long time. And we've got some MICC installations in particular that are still going very, very well with being well, well over 25 years old.