Regulation 443.4 requires protection against transient overvoltage’s to be provided where the consequence caused by over voltage could result in serious injury or loss of human life, interruption of public services and /or damage to cultural heritage, interruption of commercial or industrial activity; or affect a large number of collocated individuals. These regulations, therefore, cover all buildings other than standard domestic dwellings, so in these instances surge protection must be installed. For domestic dwellings a risk assessment according to regulation 443.5 shall be performed to determine if surge protection is required. If the risk assessment is not performed, the electrical installation shall be provided with protection against transient overvoltage, except for single dwelling units where the total value of the installation and equipment therein does not justify such protection.
Considering the price and availability of surge protection devices it seems valid to recommend their installation in domestic dwellings regardless of risk assessment. It is better to have it and not need it, rather than need it and not have it. If declined recommendation can be noted on the schedule of test results or the periodic inspection report.
Surge protection (type 1 or type 2) should be fitted at the origin of the supply to the property. This can be installed inside the existing consumer unit, fed from the consumer unit, and fitted in its own enclosure or fed from the supply tails and fitted in its own enclosure. The combined length of the conductors in relation to the current path should be <0.5M and not exceed 1M.
LIVE + CPC = <0.5 Meter (Max 1 Meter)
NEUTRAL + CPC = <0.5 Meter (Max 1 Meter)
If type 3 protection is required (for sensitive devices); this should be installed close to the equipment it is protecting to further remove smaller transients.
