An Electricians guide to Surge Protection.
The whole nature of how electrical equipment is used in homes and at work has evolved; with everyday activities relying on electronic equipment.
Products such as computers, printers, flat screen televisions, industrial control equipment such as PLC’s, alarms, microwaves and washing machines are common place. These can all be vulnerable to transient overvoltage’s, which can significantly reduce the equipment’s lifespan through degradation and damage.
A transient overvoltage or surge is a short duration increase in voltage measured between two or more conductors. In short this means anything from microseconds (millionths of a second) to a few milliseconds (thousandths of a second) in duration.
Surges & The Dangers
Surge Protection Devices
SPD’s protect electrical and electronic
equipment against transients, originating
from lightning, switching of transformers,
lighting and motors. These transients can
cause premature ageing of equipment,
downtime, or complete destruction of
electronic components and materials.
18th Edition Requirements
The 18th edition BS 7671 now stipulates: Protection against transient over-voltage’s shall be provided where the consequences caused by an over-voltage could
(i) result in serious injury to, or loss of, human life, or (ii) result in interruption of public services and/or damage to cultural heritage, or (iii) result in interruption of commercial or industrial activity, or
(iv) affect a large number of co-located individuals.
For a single dwelling unit, it will be a decision for the house owner to make whether they consider the small additional cost of the surge protection device justified to protect their installation and equipment against these damaging overvoltage’s. If the owner declines the installation of an SPD they should sign and print their name on a document stating they do not wish to have the device fitted.
Most SPDs have an indication window that they are operational. If the indicator is green, they are providing protection. If they are red then they have reached ‘end of life’ and will need replacing. Often there is a replaceable cartridge which can simply be withdrawn and replaced with a new operational device.