Surge protection Requirements

[DNS1]

Excuse the probably stupid question!

I'm a bit out of date, so not yet up to speed on 18th edition.

Been prepping for a domestic board change, but am confused about whether I need an SPD or not.

Seeing as the majority of suppliers are selling their boards without the SPD, I'm assuming they're not an absolute requirement, but I'm having a hard time finding something to confirm this.

This is a bog standard domestic set-up, nothing fancy at all, was new build in 2001 so all pretty straightforward.

Can someone point me in the right direction?

Cheers

 

[bill01803]

See section 443

 

[Ian1981]

Have a read of regulation 443.4

 

[DNS1]

Cheers for the response, unfortunately I don't have the book yet!

Would someone mind sending me a screenshot/photo of the relevant section?

 

[Ian1981]

Cheers for the response, unfortunately I don't have the book yet!

Would someone mind sending me a screenshot/photo of the relevant section?

Here you go

 

[DNS1]

Thanks for that...

I'll have to read up on doing the risk assessment...

I wonder if the fact that there are no exposed cables between the house and substation will satisfy the regs... It all seems rather OTT IMO!

 

[plancaster]

Hi For what they cost why not?
Phil

 

[DNS1]

Hi For what they cost why not?
Phil

I'm just not sure what they achieve!

Unless there is an issue with the supply from the DNO (which will make them liable anyway!) what can they protect against?

There's no chance of a lightning strike as there are no overhead cables between the property and the substation.

If they're that important, why doesn't the DNO have to supply them?

 

[Julie.]

You don't need to do the risk assessment for a single dwelling, if you read it closely there is a section about it purely down to cost of protection vs value of the installation.

If the householder doesn't deem it worthwhile, you don't have to install it.

Depending on the cu you are using, it could be a cheap addition, or overly expensive.
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I'm just not sure what they achieve!

Unless there is an issue with the supply from the DNO (which will make them liable anyway!) what can they protect against?

There's no chance of a lightning strike as there are no overhead cables between the property and the substation.

If they're that important, why doesn't the DNO have to supply them?

The real issue is that small surges was never a problem traditionally, however now that most lighting is led, almost all appliances have electronics, etc, then even a small switching surge could cause expensive issues.

From an installers pov, if you do a cu change and then half the led lamps fail 6 months later, you would likely get the blame even though the cu change has nothing to do with it!

 

[freddo]

unfortunately I don't have the book yet!

Why not? It's been out for ages!

 

[Ian1981]

The thing to remember is you only need to protect against transient overvoltages originating from the distribution network, switching surges from within the installation only need to be considered for protection, this is often mistaken for being a requirement rather than a consideration

 

[pc1966]

I'll have to read up on doing the risk assessment...

There are several cases where the new regs say you must, basically anywhere there is any lighting conductor system in use (in that case you also need a Type 1 SPD), a risk to life (e.g. hospital, etc), or risk of a loss of business continuity (so every work place!) but for homes it usually comes down to the "risk assessment".

Realistically some companies (e.g. Fusebox) include a Type 2 SPD as standard now, so you just go with it as no extra effort, and for many others it is under (sometimes well under) £100 for it anyway.

You could argue that mains-powered stuff ought to be competently designed to deal with surges, but sadly that is not the norm in today's cost-cutting world and cheap s**t LED lights and consumer electronics is the norm.

 

[Markyd]

single dwelling...recommendation only...if the client says no then you dont have to fit one...and why have you not got the 18th edition ..only came out in January 2019

 

[davesparks]

I'm just not sure what they achieve!

Unless there is an issue with the supply from the DNO (which will make them liable anyway!) what can they protect against?

There's no chance of a lightning strike as there are no overhead cables between the property and the substation.

If they're that important, why doesn't the DNO have to supply them?

Liability doesn't matter, the DNO being liable won't magically prevent anything from being damaged. No payment in respect of that liability will replace lost data.
The point of the SPD is to protect equipment from surges.

A lack of overhead cables doesn't prevent lightning hitting the substation or the upstream HV lines.

Why would the DNO supply SPD's? RCDs, MCB's, main bonding are all important but the DNO don't supply them!
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I'm a bit out of date, so not yet up to speed on 18th edition.

Then don't do, or design, electrical work until you are. The 18th edition has been in place for over a year now.

 

[pc1966]

A lack of overhead cables doesn't prevent lightning hitting the substation or the upstream HV lines.

There is another thread that ended up discussing SPD here:

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One of the folks on this forum (Mike Johnson) reported that his Type 2 SPD in France keeps burning out on the end of a SWA cable so in rural cases it looks as if a Type 1 may needed to deal with magnitude of surges on long underground feeds without overhead cables even being a factor.

OK, that region is more lightning prone than most of the UK, and it is odd in that the French provide a TT supply off a SWA cable, so what do they do with the SWA's earth? A discussion for another day...