Wylex T2 surge protector TT?

[AndyPRK]

Hi

Are these suitable for an underground TT supply please?

Thank you

 

[JohnW2]

Are these suitable for an underground TT supply please?

What do youy mean by 'suitable'? Are you thinking that the fact that it is a TT supply alters the requirements?

As you probably know, unless/until I can find some reasonable 'evidence', I am very much an 'SPD sceptic' as far as domestic installations are concerned. Having 'declared that interest', I think I would be even less convinced with a a need/value of an SPD with an underground supply than with an overhead one. I think you'll find that if you use the BS7671 calculation to determine whether SPD protraction is 'needed', it will usually say 'no' if the supply path is entirely underground.

Hopefully others will have more useful answers for you!

Kind Regards, John

 

[flameport]

TT supply

Yes.

2 module: https://docs.electrium.co.uk/Datasheets/DataSheet_NHSPD4621T2.pdf
1 module: https://docs.electrium.co.uk/Datasheets/DataSheet_NMT2SPD3W-1.pdf
Both stated as suitable for TN-S, TN-C-S and TT.

The risk assessment in BS7671 is irrelevant.
Most transients are caused by switching, not by lightning.

 

[JohnW2]

The risk assessment in BS7671 is irrelevant.

Why is it included in BS7671, then?

Most transients are caused by switching, not by lightning.

Maybe, but I'm still waiting for convincing evidence that electronic equipment is 'commonly' (more commonly than 'once in a blue moon') damaged by such transients.

As I always observe, I'm rather fascinated by the U-turn that occurred in recent times on the part of some of those who, only a small number of years ago, responded to any mention of 'surge protection' with ridicule and references to 'charlatans' and 'snake oil'

Kind Regards, John

 

[AndyPRK]

Thank you.

It was a 2 din one I was looking at. Are the 2 din width ones better ? Absorb more? (from the same brand)

 

[ericmark]

I'm rather fascinated by the U-turn that occurred in recent times on the part of some of those who, only a small number of years ago, responded to any mention of 'surge protection' with ridicule and references to 'charlatans' and 'snake oil'

I will admit a few years ago I did regard them as snake oil, I am still not convinced, however I am now looking at them a little different to how I looked at them 10 years ago.

The first surge protection or filters supplies were seen as computers arrived, and related to switch mode power supplies, and computer power supplies did fail, but it seemed the main component failure was the capacitor and we all know the electrolytic capacitor has a limited life.

But now I look back and get chicken and egg, was it the capacitor which caused the rectifier to fail, or the failed rectifier causing capacitor to fail?

Then we got LED lights, I have been lucky, very few have failed, or was it luck, or was it because I fitted a SPD?

Also go back before 2008 RCD's were not that common, and the filters often leaked to earth, but as the RCD ended up on all circuits, these filters leaked a lot less to earth, again I remember early computers and how putting 6 on same RCD could cause problems, but today we see a trolley load wheeled into a class room all supplied with same RCD and no trip, with many laptops having a fig of 8 supply lead i.e. no earth.

The SPD goes before the RCD so will not affect it, and so many items today have a rectifying diode before any smoothing, once DC and fed into a capacitor then likely any spikes will be absorbed, but if a spike kills the diode the diode dying will likely have a knock on effect.

So my old house now my sons, he to my mind went mad with down lights but he has had many fail, so question is if due to poor quality, or spikes?

I always felt we had a problem from time to time with spikes, as in the main the RCD's would hold for years, but every so often we would get a bout of trips, no fault found and then again would run for years without a failure.

Where my son has fitted the LED down lights which have failed, I fitted a 24 watt LED fluorescent tube replacement which only lasted 18 months, of which most of the time the house was empty, replacement lasted OK.

I am not saying these bulb failures are due to surges or spikes, the question is why did I not also loose living rooms and dinning room lights, 16 bulbs in all, after going LED the many failures with the Philips 8 watt CFL was a thing of the past, but could those Philips lights failed due to spikes?

The answer is no one knows, fact that the cheaper golf ball lamps from Home Bargains did not fail points to the expensive Philips lamps being low quality, but who knows?

Some things don't seem to make sense, when I got fusebox SPD there was no MCB, but today they are fed through an MCB, the MCB has some resistance so will reduce the effectiveness of the SPD, so why add it? If there is a danger if not MCB protected then should be a recall on the consumer units fitted without MCB, but that does not seem to have happened.

So yes I am uncertain if the SPD helps, but I have still fitted one, at £30 for the fusebox version not worth taking the chance.