Building Services
Utilities and building services are not generally designed to operate when submerged in water. Wherever possible they should be located above the level of potential floodwater. Where this is not feasible equipment should be specified with appropriate protection against water ingress. This will help ensure services remain operational during a flood or can be restored with minimal effort once the water has subsided.
Utilities
These are the electricity, gas, water, drainage and communication services that are provided by energy network operators. They generally enter a building below ground, and the meter, service cut-out and isolation valve are located inside or outside the property. If inside, they tend to be on the lowest level of the building – either in the basement or on the ground floor. Electrical cabling and gas pipework will survive being submerged in water, but the electricity cut-out and meters for both are not designed to withstand floodwater.
If floodwater is about to enter the property, it is safest to turn off utility supplies. Turn the gas supply off using the emergency control valve which is normally located next to the gas meter. Turn the electricity supply off using the isolator switch or fuse unit. These will be found where the metering cabinet is located. Only attempt to turn them off if it is safe to do so.
If the property is supplied with Liquified Petroleum Gas (LPG), be aware that floodwater can cause the LPG bulk storage vessels and gas cylinders to move or become detached from installation pipework. If your LPG is supplied by cylinders, and it is safe to do so, turn off the valve at the top of each cylinder. Before carrying out any work you must contact your LPG supplier for advice regarding LPG cylinders.
To avoid the need to isolate services during a flood, and to reduce the risk of damage or loss of access, the entry points for gas and electricity supplies, along with their associated metering and isolation equipment, can be relocated above the identified flood risk level. This could be a higher location on the ground floor, or up to the first floor. It is a costly job but it may be worth doing when the building is next rewired or other work undertaken. At the same time circuits can be rewired and the consumer unit/fuse board relocated to a higher position. Where cabling and pipework enter a building, ensure the gaps are sealed, and regularly check for any degradation.
If the gas meter or any gas appliance has been submerged in floodwater, call your gas supplier before switching the gas or appliance back on. If you smell gas or suspect a gas escape has occurred, call the National Gas Emergency service number for your area immediately. If the electricity meter or cut-out has been submerged in water, contact the National Grid to arrange a visit.
Electrical installations
Before undertaking any changes or additions to an electrical installation, it is important to establish its condition. This is done by inspection and testing. All electrical installations are subject to periodic inspection and testing to ensure they are in a satisfactory condition and can be used safely. After the inspection and testing, an Electrical Installation Condition Report (EICR) is issued. This determines whether the installation is considered safe, and how quickly action needs to be taken to remedy any issues. It also includes the age of the installation and a recommendation for when the next test should be done.
The interval between inspections should reflect the type of installation, how it is used and operated, its age and any known maintenace issues or external factors that may affect it. For domestic properties, an EICR should be carried out at least every 10 years. For non-domestic buildings the maximum interval is five years.
Periodic inspection and testing should only be undertaken by a competent person who has the necessary education and experience. Suitable electricians can be found via the National Inspection Council for Electrical Installation Contracting (NICEIC) or National Association of Professional Inspectors and Testers (NAPIT) list of registered members.
For electrical works in the home, it is important that the electrician is Part P registered. Part P of the Building Regulations ensures that all electrical work in the home is carried out safely by a qualified electrician and that building control is notified of this work.
Circuit wiring
The fuse board/consumer unit should be located above the known flood level and circuits should feed individual floors, so power can be maintained above the ground floor during a flood. Floors that are flooded should be safely isolated at the fuse board/consumer unit.
As an example, lighting and sockets should be positioned above the flood risk on the ground floor. If they can't be or do not have the appropriate degree of protection against water ingress then operating them during a flood would not be safe. In this instance, the circuits feeding the lighting and sockets should be isolated at the fuse board/consumer unit and locked off so they cannot be accidently energised before it is safe to do so.
If lighting and sockets are on the first floor and the fuse board/consumer unit feeding them is on the same level, it would be acceptable to operate them during a flood if the circuits can be isolated.
All electrical circuits should have Residual Current Device (RCD). RCDs are more sensitive than standard fuses or cicuit breakers and are specifically designed to protect people from injury, particularly in higher risk areas.
Mounting of electrical accessories and wiring containment
The design of new building services within historic buildings should take advantage of any existing openings and services routes. When building uses change, or services come to the end of their life, removal and replacement must be done in a way that limits damage to the building fabric. Surface-mounted installations are sometimes the best option because they are less disruptive to remove and replace.
Fuse boards/consumer units should be mounted above the flood risk or on the first floor, along with the incoming metering and cut-out. This may mean that some services can be used during a flood, but caution still needs to be exercised.
Electrical sockets, switches, lighting and wiring containment should be surface mounted where possible. That way it will be far easier to replace them if they are damaged during a flood.
The positioning of electrical equipment like fuse boards/consumer units and sockets may need to be discussed with a local conservation officer, particularly if they are to be fixed to historic fabric.
If a continuous power supply is vital, then a back-up generator can be used. The generator and fuel store (if required) would need to be above the flood risk. Generators need to be tested monthly, and an annual load bank test is recommended to prove the generator is capable of delivering maximum load. It is also recommended to have enough fuel for the duration of a flood, which may mean additional fuel storage.
Generators use diesel or petrol to produce electricity and are fitted with an exhaust pipe. It is important to ensure that the exhaust discharges to the outside and is positioned well away from air intakes, windows or doors that can be opened to prevent harmful gases from entering occupied spaces.
If the fuse board/consumer unit or any part of the electrical installation has been in floodwater, do not switch the electricity back on until it has been inspected by a registered electrician. They will be able to check the entire installation, including appliances. They should then carry out an EICR to assess the condition of the wiring and equipment and decide if any repairs or replacements are required.
If there is major flood damage to the electrics or the flood water is contaminated, it is likely that parts of the electrical installation will need to be replaced and rewired. If the water damage is relatively minor and caused by clean water (that is, a burst water pipe or tank), then the registered electrician may be able to dry out the cables and replace any accessories affected by the water (sockets, switches, plugs and so on).
If the electrical services have not been in floodwater, you still need to ensure that all appliances and lighting are properly switched off and dry before the electricity is turned back on.
Ingress protection ratings
If electrical equipment does not have the correct degree of protection against water ingress, it should not be used where there is water – because there is an increased risk of electric shock. The risk is even greater if the person operating or in contact with the equipment is wet.
Electrical and electronic equipment can malfunction when it is immersed in water. The International Electromagnetic Commission (IEC) has developed ingress protection (IP) ratings, which grade the resistance of an enclosure against the intrusion of dust or liquid. The ratings are widely used throughout industry, and equipment is marked with the rating to which it conforms.
The IP rating comprises two numerals. The first refers to the protection against solid objects and is rated on a scale from 0 (no protection) to 6 (no ingress of dust). The second rates the enclosure's protection against liquids and uses a scale from 0 (no protection) to 9 (high-pressure hot water from different angles).
Equipment needs to be rated to IP67 for temporary immersion in water, or IP68 if it will be submerged for longer periods of time.
Heating installations
Boilers, heat pumps, LPG bulk storage vessels and gas cylinders should be mounted above the flood risk. This may mean they can remain functional during a flood, but if not it will help with their reinstatement after the event.
If the heating system has radiators and thermostatic radiator valves, these may be waterproof. However, you would need to check they have the correct degree of protection against water ingress.
Where electrical wall heaters are installed, make sure they are fed from above and are removable. The fused connection unit should be at least 1200mm above the finished floor level, and the circuit should be isolated during a flood.
If the existing ground floor finish has already been lost, this may be the time to install a wet underfloor heating system. Underfloor heating uses pipe coils that operate at low temperatures or electrical elements below the floor surface. Adding underfloor heating to a historic interior can be challenging. But where flooring has to be lifted and replaced for other reasons, it could be a discrete way to heat a building without the worry of wall heaters that could be damaged or need cleaning after a flood. The limited heat output needs to be noted. Underfloor heating alone may not be sufficient, and additional heat emitters may still be needed.
A wet underfloor heating system – fed by gas, oil or a heat pump, with distribution through pipework in the floor – can be reinstated relatively quickly after a flood as long as the boiler or heat pump and electrical supply are above the flood risk. The underfloor heating may even help with drying out the building fabric.
Part of the system may remain operational during the flood. This will depend on the configuration of the zones from the heating manifold – each zone will have its own heating loop. If the underfloor heating system is electric and embedded in the floor, the circuit will need to be isolated during a flood.
Where possible ensure that all mechanical and electrical equipment is above the highest point at which flood water is predicted to reach. This information can be established via a Flood Survey. This might not be possible with plug sockets, or where the space above is occupied by a different owner or tenant.
Where they can't be relocated and services are to be retained, it is important to ensure they have the correct ingress protection (IP) rating to withstand being submerged for a period of time and remain useable after the event.
In larger buildings (e.g. those used for museums or as visitor attractions) this might not always be possible, necessitating emergency planning to mitigate damage and ensure safety to those attending after a flood event. It is important to ensure staff are familiar with the isolation of services and their means of isolation, particularly where they are in basements. Good signage and established instructions on how to isolate these safely is important.