Protecting Cables from Water Damage
Avoiding water damage to cables is straightforward providing the right procedures are followed in line with the relevant British Safety Standards.
Electrical water damage can pose enormous risks, especially when it involves cable flood damage. Flood water can contain all sorts of contaminants, such as oil, sewage, chemicals, and many other kinds of toxic waste, meanwhile salt water is not only corrosive but conductive.
It is possible to recondition and replace damaged equipment – but clever cable management should include an initial risk assessment to avoid water damage to cables in the first place.
Therefore, if there is a likelihood of water damage, either from flooding, condensation, or where cables must be immersed in or situated near water, there are precautions which should be followed.
These come under Regulation 522–03–01 of BS 7671 which states that
“A wiring system shall be selected and erected so that no damage is caused by condensation or the ingress of water during installation, use or maintenance.”
Dos and don’ts
PVC–insulated and non–armoured cables
- DO ensure that cables for voltages up to and including 450.750 V for power and lighting meet requirements for BS 6004, and that similar cables featuring thermosetting insulation, which emit low levels of smoke and corrosive gases when subject to fire, meet BS 7211.
- DO NOT allow either of these types of cable to have prolonged contact with, or become immersed in water, as this could damage their insulation resistance and cause them to deteriorate.
- DO refer to the manufacturer’s advice when selecting cables to be installed in a conduit or trunking, or in any other type of covered system which may give rise to condensation or moisture.
- DO install cables carefully into conduits, trunking or ducting to ensure that no damage is done to the insulation.
- DO provide drainage outlets for water to escape when using cables suitable for containment systems containing condensation or moisture, for example in cold or outdoors environments.
- DO incorporate a “fall”, with drainage outlets at the lowest point to facilitate the escape of water.
- DO ensure that:
- armoured cables with PVC insulation adhere to BS 6346;
- armoured cable with thermosetting insulation is covered by BS 5467; and
- armoured cable that emits low levels of smoke and corrosive gases when subject to fire meets the requirements of BS 6724.
- DO take note that all three types of cable are suitable for burial in free–draining soil conditions.
- DO take care not to damage cable covering when placed in wet or aggressive environments.
- DO seal the ends of cables to prevent water ingress during transportation and storage, and leave moisture caps on as long as possible until completion of installation.
- DO NOT situate cable where it may become immersed in water, or where water may collect.