What are SPD's and Do I need one ?

We have been contacted recently by several people asking about SPD’s and whether they need them, so have put together some information from sources like the IET and ECN in a concise article to shed some light on them.

First, what is an SPD? 

An SPD (Surge Protective Device) is used to protect your electrical installation from electrical power surges known as Transient Overvoltages (a spike in voltage). Items of Electrical equipment with sensitive components are at greater risk of damage from these instances.

All electrical components are susceptible to surges, and these can be natural (from lightning) or man-made (from overloading or switching).

“The effects of a surge can result in either instant failure or damage to the equipment only evident over a longer period. SPDs are usually installed within the consumer unit (Fuse box) to protect the electrical installation but different types of SPD are available to protect the installation from other incoming services, such as telephone lines and cable TV. It is important to remember that protecting the electrical installation alone and not the other services could leave another route for transient voltages to enter the installation.

There are three different types of Surge Protective Devices: 

·         Type 1 SPD installed at the origin, e.g. main distribution board. These are designed for direct lightning Strikes

·         Type 2 SPD installed at sub-distribution boards - Designed for indirect lightning strikes and Switching Overvoltages

o    (Combined Type 1 & 2 SPDs are available and are usually installed in consumer units).

·         Type 3 SPD installed close to the protected load. They must only be installed as a supplement to Type 2 SPD.

Where multiple devices are required to protect the installation, they must be coordinated to ensure correct operation. Items supplied by different manufacturers should be confirmed for compatibility, the installer and manufacturers of the devices are best placed to provide guidance on this.”

For accurate Pricing you can find these components readily available online to check you are getting a fair price.

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Secondly, Do I need an SPD?

They have been around since the 70’s but have recently become more widely spoken about since the 18th edition of the BS7671 wiring regulations highlighted some important points on their uses in todays modern world of technology. Where we have become so reliant upon the use of electrical equipment both at work and at home.

Since Covid-19 more and more people are working from home without the need to return to offices, meaning our computers and Wi-fi are the lifeline we feel we can’t afford to lose.

The current edition of the IET Wiring Regulations, BS 7671:2018, states that unless a risk assessment is carried out, protection against transient overvoltage shall be provided where the consequence caused by overvoltage could:

·         Result in serious injury to, or loss of, human life; or

·         Result in interruption of public services and/or damage to cultural heritage; or

·         Result in interruption of commercial or industrial activity; or

·         Affect many co-located individuals.

For a homeowner though, this means that your local electrician could visit your property and conduct a survey to gain as much information as possible before doing a risk assessment on site and either ruling out the requirement of SPD’s or recommending them to protect the system you have. In essence: a single unit dwelling I.E a house, the decision on whether to Purchase SPD’s and have them installed is with the customer.

…Although it Is worth checking with your insurance company as some policies may state that equipment must be covered with an SPD or they will not pay-out in the event of a claim.

 

What are Transient Overvoltages?

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The most obvious type of Transient overvoltage is a Lightning strike. A single lighting strike can contain 200,000A which if struck at or near power transmission lines would generate a significant voltage transient. This voltage transient could cause significant damage to both domestic and commercial electronic equipment.

Here is a Map showing the frequency of Days we have thunder in the UK distributed by Hager, a well-known Supplier of SPD’s. this could be used as part of the process for determining risk to your property’s electrical installation.

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The other main cause of Transient Overvoltages is less obvious, they are caused by switching on the electrical distribution network which influences all types of equipment downstream. The problems caused by transient overvoltages, whether lightning or electrical switching induced, range in consequence level and can be broadly classified into

·         Disruptions - Disruptions result in no physical damage, but nuisance upset to electronic systems are caused, involving data loss, software corruption, system crashes and spurious tripping

·         Degradation - Degradation is the gradual deterioration of components due to long-term lower level transient overvoltages reducing the life of components and susceptibility to premature failure.

·         Damage - Damage manifests in burnt-out circuit boards through overheating and insulation failure and exacerbated by the subsequent power follow-on. Damage can also occur due to poor operation/ short-circuit caused by the transient overvoltage.

·         Downtime - Downtime is the interruption to work/ operations resulting in lost business and increased costs.

Whilst the IET Wiring Regulations are not retrospective, where work is being carried out on an existing circuit within an installation which has been designed and installed to a previous edition of the IET Wiring Regulations, it is necessary to ensure the modified circuit complies with the latest edition, this will only be beneficial if SPDs are installed to protect the whole installation.

Surge protection could be installed in an existing consumer unit if appropriate physical space was available or, if enough space was not available, it could be installed in an external enclosure adjacent to the existing consumer unit.

The decision on whether to purchase SPDs is in the hands of the customer, but they should be provided with enough information to make an informed decision on whether they wish to omit SPDs. A decision should be made based on safety risk factors and following a cost evaluation of SPDs, which may cost as little as a few hundred pounds, against the cost of the electrical installation and equipment connected to it such as computers, TVs and necessary equipment, for example, smoke detection and boiler controls.

Sources: IET-(https://electrical.theiet.org/courses-resources-career/free-resources/consumer-guidance/surge-protective-devices/)

Hager: (https://www.hager.com/)

For more information from your local electrician in Maidstone, Medway or the Kent area in general, head over to the contact page and drop us an email or call us and we will be happy to answer any more questions you may have.