It is currently 28 Mar 2024, 21:00

Surge protector in CU - any experience?

This is the place to go with all your issues, questions or handy hints on all things related to motors, electrickery, engineering, metalwork etc...

Surge protector in CU - any experience?

Postby AJB Temple » 17 Jan 2022, 18:24

We are presently installing additional electrical circuits via an additional consumer unit in a location remote from the CU and at the same time will have inspection and test as necessary for the original set up, with Hager main CU installed in late 2015 not long after we moved in, and various alterations and additions in late 2018.

The system is TN-C-S. No isolator switch on the main board (outside) but quite obviously someone has pulled the main fuse (100Amp) as it has no seals. The installation was upgraded by the supply company back in 2015 mainly to provide beefed up 25mm tails and 16mm earth, from whatever was there before. This was at the request of my then electrician. It is therefore all quite new.

I have three spare slots in the main CU and a genuine Hager type 2 surge protection unit would take 2 of those. We have been experiencing failures in good quality LEDs (Phillips) and being a) out in the sticks and b) fed by overhead powerline afflicted by tree encroachment, I am wondering if overvoltage surge is a factor.

Does anyone have any experience of CU surge protectors (as opposed to the extension lead type which are no use on things like ceiling lights)? Any pros and cons? I know that SPs wear out over time as they absorb the surges, but I can always replace the cartridges after a few years.

The extra work is Part P notifiable and I have not engaged an electrician yet though I have one on standby for mid Feb. I am just doing my research on the overall spec. The surge protector is just an add on that I could do as well as the main work.
Don't like: wood, engines, electrickery, decorating, tiling, laying stone, plumbing, gardening or any kind of DIY. Not wild about spiders either.
User avatar
AJB Temple
Sequoia
 
Posts: 5431
Joined: 15 Apr 2019, 09:04
Name:

Re: Surge protector in CU - any experience?

Postby spb » 17 Jan 2022, 19:19

My experience is limited to having had one fitted as part of a new CU in 2019, but being in a city, and an area not prone to lightning storms, it's very much a "well, it doesn't hurt" sort of a choice.

I'd say if you suspect there might be overvoltage events happening, it won't hurt anything to fit one and see. Unlike other protective device upgrades, they won't cut the power if they trigger, and even if they do get burnt out by sinking a particularly high spike, all that'll happen is that it won't protect you next time. If you've got the space in the existing board, it's basically risk free to fit one and see.
spb
Nordic Pine
 
Posts: 569
Joined: 27 Sep 2020, 20:25
Location: Cambridge
Name: Stephen

Re: Surge protector in CU - any experience?

Postby RogerS » 17 Jan 2022, 19:27

Bob's really your man for this but have you checked what your voltage is? Ours is 258v nominal until we start loading it a bit.
If opportunity doesn't knock, build a door.
User avatar
RogerS
Petrified Pine
 
Posts: 13291
Joined: 21 Jul 2014, 21:07
Location: Nearly finished. OK OK...call me Pinocchio.
Name:

Re: Surge protector in CU - any experience?

Postby AJB Temple » 17 Jan 2022, 19:39

Yes Roger. On my Megger MFT 1711 it tests unloaded at 232V today. We are the first stop from the high voltage overhead line transformer.

Lightening strikes are not the main cause of spikes. In my case what concerns me (and suspect as the cause) is overhead supply hv lines crossing coniferous tall trees in adjacent woodland. The DNO is aware of this and has it scheduled for tree trimming, but this could be some months apparently (they have a backlog). They were originally going to do it last summer but it was delayed. Trees are now in contact with the lines. (It is not on my land). The issue appears to be a shortage of suitably qualified and insured tree surgeons.
Don't like: wood, engines, electrickery, decorating, tiling, laying stone, plumbing, gardening or any kind of DIY. Not wild about spiders either.
User avatar
AJB Temple
Sequoia
 
Posts: 5431
Joined: 15 Apr 2019, 09:04
Name:

Re: Surge protector in CU - any experience?

Postby Phil » 18 Jan 2022, 13:29

We had one installed after a lightning strike.

It is external (next to) the CU
Above that we have a large switch which changes us from mains to generator, and all runs through the SP.
Seems to provide enough protection, the sparky did say if there was a direct lightning strike we would be stuffed in any case.
We don't stop woodworking because we grow old, we grow old because we stop woodworking!

https://www.instagram.com/phil_pretoria/
User avatar
Phil
Old Oak
 
Posts: 3499
Joined: 23 Jul 2014, 05:11
Location: Southern Africa 0054
Name: Phil

Re: Surge protector in CU - any experience?

Postby AJB Temple » 18 Jan 2022, 14:21

Thanks Phil. I think I will go ahead.

The 18th Edition regs require that the cables to the supply, including CPC do not exceed 1 metre (and ideally not more than 50cm) cumulatively in total. This makes installation in an external metal box (usually with a 32 amp breaker and isolation switch) quite tricky as the lengths include the cabling through the CU as well as external visible cabling. There are a number of YT videos from trainers and people like John Ward about this as a lot of installations may not be compliant due to initial confusion about what the proximity rules were. Unfortunately I don't think we have enough space to use an external box in sufficiently close proximity, though I would prefer it as it wastes slots in the CU otherwise.

Manufacturers have started to supply populated CUs with built in surge protectors now. I think we will start to see far more of them, though they are not a requirement for Part P or 18th edition in domestic installations. With the amount of sensitive electronics in many houses though (including in white goods as well as TVs and computers and smart lighting systems), it seems like a sensible and pretty cheap precaution to me.
Don't like: wood, engines, electrickery, decorating, tiling, laying stone, plumbing, gardening or any kind of DIY. Not wild about spiders either.
User avatar
AJB Temple
Sequoia
 
Posts: 5431
Joined: 15 Apr 2019, 09:04
Name:

Re: Surge protector in CU - any experience?

Postby 9fingers » 18 Jan 2022, 14:25

RogerS wrote:Bob's really your man for this but have you checked what your voltage is? Ours is 258v nominal until we start loading it a bit.


Sorry guys I've no experience or knowledge about surge protectors apart from the sparky who did an EICR on my late parents house. The report noted that one was not fitted. When I queried it with another electrician friend he dismissed the observation as he said I did not need one.
So clearly not mandated but rural installations with a history of surges might well benefit from one. I agree that one fitted in CU is unlikely to offer any direct lightning protection.

Bob
Information on induction motors here
https://drive.google.com/file/d/1dBTVXx ... sp=sharing
Email:motors@minchin.org.uk
User avatar
9fingers
Petrified Pine
 
Posts: 10038
Joined: 21 Jul 2014, 20:22
Location: Romsey Hampshire between Southampton and the New Forest
Name: Bob


Return to Engineering - Electrical/Metalworking

Who is online

Users browsing this forum: No registered users and 8 guests

cron