RCD trips in power outs

[bernardgreen]

It might be a few appliances with mains input filters ( capacitors to ground ) and the transient voltages on phase and a bouncing neutral as the network phases and neutral settle down after reconnection.

 

[stunlawless]

Bernard, good point.

My plan:
1. Find out if it trips on power off or power on
2. Find out if RCD trips if all MCB's off
3. If not, add MCB's until it does
4. See if it still happens with everything disconnected on this cct
5. If it still happens, investigate this cct
6. PIR on the whole install anyway
7. Remedials !
8. Replace VOELCB with switch fuse (CU is a long way from cut out & VOELCB)
9. See if it still happens
10. Beers & congratulations all round!

Thanks David

 

[ban-all-sheds]

Re #8.

i) this should be promoted to #1, as it's got to happen anyway and there's little point in doing any "what happens when"s just in case it is implicated.

ii) how will you isolate the supply?

 

[stunlawless]

1) Want to be able to repeat the failure ensure it's fixed.

2) fold the tails double and secure with a cable tie. That should keep the electrons in.

 

[ricicle]

Remember switch fuse will need to be insulated.

 

[ban-all-sheds]

1) Want to be able to repeat the failure ensure it's fixed.

But not test failure modes or validate fixes on the installation you'll be using?

fold the tails double and secure with a cable tie. That should keep the electrons in.

You're going to remove live tails from the VOELCB, and then insert live tails into the switchfuse?

That is known as a Bad Idea™.

 

[stunlawless]

Ricicle, why shouldn't I use a metal clad with appropiate bonding ?

BAN, SOH gone AWOL ?

David

 

[252warks]

Hi all, I have a protek 63amp 30mA RCD that seems to be too sensitive ie tripping when a bulb blows etc which is annoying as we have to reset heating controls miss tv recordings let alone alarm calls???

Would changing the RCD help if so which one would changing to the 100mA protek help??

 

[EFLImpudence]

It's rude to but in - start your own topic.

Edit - I have answered in new thread

 

[kkynaston]

2) fold the tails double and secure with a cable tie. That should keep the electrons in.

I've just woke up the wife with my laughing, I'm gonna use that one I think

 

[plugwash]

Ricicle, why shouldn't I use a metal clad with appropiate bonding ?

* On a TT supply the earth fault loop impedance is very high.
* Therefore a fault to earth WILL NOTblow a fuse or TRIP a MCB.
* Therefore anything prior to the main RCD CANNOT be protected by EEBADS
* Therefore anything prior to the main RCD must be protected by some other means.

While it would in theory be possible to manufacture a class 2 metalclad switchfuse i've never seen such a thing for sale.

 

[stunlawless]

Ricicle, plugwash,

Blindingly obvious now that you say it. Hadn't thought it through, thanks for pointing it out.

David

 

[1john]

Your friend needs to get an electrician in, I mean this in the kindest way but you have no idea of TT supplies, you have winged it through this post all the way. the rlcb may have been installed many moons ago to protect the cable from the cut out to the CU, it may require 30mA protection now to comply too. You cannot use RCBO's on a TT install if they are only SP. Why are you contacting current manufaturers about their DIN mounted RCD's when the only thing that you need to be doing is finding out the spec of the RCD in the CU in question. You could do alot of leg work for your friend, which could make an electricians life easier if your friends is right in the sticks.

How frequent are the power cuts?
Do you know why they occur?
Is this the only property affected by them?
If not, is there a large area affected?

 

[stunlawless]

John,

Thank you for your kind words. In hindsight, a little less haste and maybe a little less flippancy would have been better.

A TT install must be protected by an RCD. Regs could be satisfied by a 100mA time delayed device. Obviously, to protect the whole installation, this should be close to the meter.

Indivdual ccts must be protected by 30mA RCD/RCBO. I disagree that SP RCBO's can't be used in a TT install, but they can't be used as a means of isolation. That definitely requires a DP device. In any case, DP RCBO's are readily available, but the ones I've seen have L & N at the top & bottom, making them unsuitable for a conventional consumer unit with a busbar arrangement.

In this particular install, I'm not sure of the exact length of the tails from meter to CU but I think it would exceed 2.5m, so a switch fuse would ordinarily be required (Note: at the moment, I don't know who the DNO is, so I don't know what their precise requirements are).

I don't think a 63A 100mA time delayed RCBO exists, so that's not an option, so it looks like a Wylex insulated switch fuse and a RCD in an insulated enclosure.

Alternatively, a 63A MCB B type might be suitable. I'll have to look at the difference in overload & SC protection characteristics whwn I get near the BRB.

As regards the power cut events, they are occur "several times each year", and can be at any time of the year, and can lst from minutes to hours. Not sure how big an area is affected - certainly the immediate neighbours are off as well, but lack of streetlights and rolling countryside makes it difficult to work out haw far the lights have gone out.

Ideally, the DNO would fix it, but tis the nature of the beast that overhead supplies will be less reliable than underground due to the elements.

Thanks, David