SURGE & CIRCUIT PROTECTION FEATURE
OVERVOLTAGE PROTECTION SHOULDN’T BE FORGOTTEN
Jimmy Higginbotham, product manager for circuit protection for Electrium, discusses how commercial installations are just as important when it comes to the 18th Edition
E
lectrical installations in commercial premises are not mentioned very
often when discussing the new wiring regulations. The irony is that, in some cases, it’s the commercial premises and their users that are most likely to benefit from the new standards. Overvoltage protection is a clear
example of this. The 18th edition says that overvoltage protection must be provided where the consequences of overvoltage incidents could result in: • Serious injury to, or loss of, human life • Interruption of public services • Interruption of commercial or industrial activity • Damage to cultural heritage • Affect a large number of co-located individuals
Clearly, a wide variety of types of premises are included in the scope of regulation 443.4. The question for the designer of the installation is how to match the likelihood of those consequences to the premises concerned and make sure that they comply with these requirements. A simplistic approach would lead us to consider hospitals and care facilities when
injury or loss of human life is mentioned. Offices and factories come to mind when considering avoiding interruption of commercial and industrial activity. Emergency services, data centres, financial organisations, and transport networks come under public services that need to be continually available. But many of these types of premises
will also have a large number of co-located individuals within, and that means that there’s often more than one reason from regulation 443.4 to consider when providing overvoltage protection in commercial installations. To assist designers and installers with
overvoltage protection requirements, Crabtree has recently introduced a simple kit for use with MCB distribution boards. This easy to install kit includes the overvoltage protection device, fixings, a cable loom and a three pole MCB. This makes it a simple design choice on large installations to include overvoltage protection at each distribution board location. Kits are available for 125A and 250A
rated B type distribution boards in the Loadstar and Polestar Compact product ranges. These Type 2 surge arresters
include local status indication on the device and an option for remote signalling. It’s difficult to imagine many types of
commercial premises that are not covered by one or more of the risks listed above, but for all other cases that may be experienced, a risk assessment to regulation 443.5 must be carried out. The risk assessment will determine the
risk level, so that the designer can decide whether to include overvoltage protection or not. But it is worth noting that instead of doing the risk assessment, the designer can opt to include overvoltage protection, ie., save time on designs and provide overvoltage protection as standard. Protection against overvoltages of an
atmospheric origin or due to switching is a requirement of the 18th Edition of the wiring regulations. Using the appropriate devices to meet these requirements will further protect the electrical installation and the valuable electrical and electronic equipment from damage by overvoltages, thereby maintaining the vital services that we all rely on every day.
Electrium
electrium.co.uk ELECTRICAL ENGINEERING | JULY/AUGUST 2019 27
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