30mA or 100mA RCD

[Cremeegg]

Just bought a small one bed flat to let out - electrics need some work - but appears to be mainly cosmetic flat about 20 years old; two CU's with BS3871 MCB's. TNCS supply Ze 0.17 all Zs readings well within limits.

I'm puzzled why there is a newish Wylex standalone 100mA RCD in the tails between the meter and the Henley block where the tails split to two CU's.

An old time clock and a new meter with integral clock but I see no reason for a 100mA RCD.

Anyone any ideas - other than that was all they had in the van at the time.

 

[PrenticeBoyofDerry]

Regulations have moved on in the last twenty years, a few years ago it was acceptable to use a 100mA RCD isolators, in thank it was acceptable not to have any RCD protection at all.
It could well be that the earthing arrangement had changed from a TT to a TNCS in recent times and the exsistance of the 100mA device relates to that or maybe as you have stated the only suitable form of isolator they had in the van.
Now you would require a 30mA device or devices.

 

[flyingsparks]

Unlikely I know being a flat, but it's not thatch roof is it?

 

[AndyPRK]

any RCD's in the CU's ?

 

[Cremeegg]

Town centre location - so always been TNCS - no sign of any earth stakes.

Ground floor flat - no thatched roof!

No RCD's within CU's

An old 30mA RCD provided as standalone alongside old CU with the radial circuit labelled jacuzzi bath run through it. Old jacuzzi bath removed by previous owner but cabling left in place and RCD not working.

Time to change to a 30mA I think - main fuse isn't sealed so that overcomes one problem!

 

[knowall]

One bed flat, how complicated do you need it to be ?

 

[ricicle]

In our area the local council used to use 100mA RCDs as the main switches in their rented properties.

 

[ban-all-sheds]

Time to change to a 30mA I think

Your electrician might refuse to install a single RCD for the entire installation.

 

[JohnW2]

Time to change to a 30mA I think

Your electrician might refuse to install a single RCD for the entire installation.

Possibly, although I suspect the risk of that would be a lot less in the case of replacing an existing single RCD (even if with a slightly different one) than it would be if the electrician were being asked to install a single RCD when there had not been any RCD previously. After all, if the existing single RCD became faulty, I would have hoped that an electrician would be happy to replace it.

In any event, in either situation, it is a fairly sad state of affairs if, in the name of 'complying with regulations' (regulations which primarily exist to promote safety) an electrician felt obliged to refuse to do something which nearly everyone would agree would increase the safety of the installation!

Kind Regards, John

 

[ban-all-sheds]

But there are alternatives which both increase safety and comply.

When regulations change you can't get out of complying with them by saying "oh well it's better than it was before".

 

[JohnW2]

But there are alternatives which both increase safety and comply.

Of course, but my main point was that I'm far from convinced that replacing an existing single RCD is non-compliant. As we know, there is no general requirement to bring existing installations up to compliance with current regs - do you believe that it is non-compliant to replace a component in an installation which is not up to current standards?

When regulations change you can't get out of complying with them by saying "oh well it's better than it was before".

That's true - but, as I said, if, in some cases, that results (as it would do) in a failure to make the installation safer than it was before, then I regard that as a sad state of affairs, and not really in keeping with what one would hope was the spirit of the regulations (essentially, increased safety).

Perhaps worse, as we've discussed before, the truth is that the regulation which (probably) makes single-RCD installations non-compliant is not really about electrical safety at all, and is only very slightly related to any sort of safety (falling down dark stairs etc.) - which, IMO, makes refusal to effect (genuine) increases in electrical safety because of that even more saddening.

I would have hoped that this is a situation in which safety-based common sense would prevail.

Kind Regards, John

 

[ban-all-sheds]

Of course, but my main point was that I'm far from convinced that replacing an existing single RCD is non-compliant. As we know, there is no general requirement to bring existing installations up to compliance with current regs - do you believe that it is non-compliant to replace a component in an installation which is not up to current standards?

I believe that if you do work on something, make changes to something, carry out improvements on something, etc, then the principle that what you do must comply with the current standards, not the ones which applied to the original something, and not just be "better than it was", is a sound one.

if, in some cases, that results (as it would do) in a failure to make the installation safer than it was before, then I regard that as a sad state of affairs, and not really in keeping with what one would hope was the spirit of the regulations (essentially, increased safety).

That's not the case here - it's not a case of not being able to do anything if compliance with the current regulations is required.

 

[JohnW2]

...do you believe that it is non-compliant to replace a component in an installation which is not up to current standards?

I believe that if you do work on something, make changes to something, carry out improvements on something, etc, then the principle that what you do must comply with the current standards, not the ones which applied to the original something ... is a sound one.

So do you believe that it would be non-compliant to, say, replace a broken plastic switch or ceiling rose on a lighting circuit which had no CPC - or, more relevant to this discussion, replace metal accessories on such a circuit with (safer) plastic ones?

...if, in some cases, that results (as it would do) in a failure to make the installation safer than it was before, then I regard that as a sad state of affairs, and not really in keeping with what one would hope was the spirit of the regulations (essentially, increased safety).

That's not the case here - it's not a case of not being able to do anything if compliance with the current regulations is required.

You seem to be missing my point. Yes, of course, it's always possible to bring an installation up to compliance with current regulations. However, my point is that some people inevitably won't be prepared (or able, financially) to do that (and there is no obligation on them so to do) - but, if they want to be 'compliant' they would then be precluded from undertaking lesser things which would increase safety - which is what I regard as 'sad'. Then there's the plight of the financially restricted person whose single RCD becomes faulty (say, fails to operate when test button pressed) - if they can't afford to change to a dual-RCD setup (which usually will mean a CU change), are we to tell them that they have to live with the non-functioning RCD, because 'regulations will not allow it to be replaced'?

Kind Regards, John

 

[ban-all-sheds]

So do you believe that it would be non-compliant to, say, replace a broken plastic switch or ceiling rose on a lighting circuit which had no CPC - or, more relevant to this discussion, replace metal accessories on such a circuit with (safer) plastic ones?

That's not a valid analogy. What would be would be, say, the replacing of a metal light switch which had dodgy, arcing, overheating contacts with another metal one, saying "Well, ni, it doesn't comply with the regulations, as there's no cpc, but it's better than it was."

You seem to be missing my point. Yes, of course, it's always possible to bring an installation up to compliance with current regulations. However, my point is that some people inevitably won't be prepared (or able, financially) to do that (and there is no obligation on them so to do) - but, if they want to be 'compliant' they would then be precluded from undertaking lesser things which would increase safety - which is what I regard as 'sad'.

It's not "sad", it's the way you gradually improve things.

Then there's the plight of the financially restricted person whose single RCD becomes faulty (say, fails to operate when test button pressed) - if they can't afford to change to a dual-RCD setup (which usually will mean a CU change), are we to tell them that they have to live with the non-functioning RCD, because 'regulations will not allow it to be replaced'?

Then there's the plight of the financially restricted person whose dodgy gas boiler develops a fault. If they can't afford to replace it, are we to tell them that they have to live without a gas boiler because the regulations will not allow it to be put back into service?

 

[JohnW2]

It's not "sad", it's the way you gradually improve things.

IMO, it's rather odd to have a way of "gradually improving things" which works by preventing people from making 'gradual improvements'! (ones which don't go far enough to comply with current regs)

It would be different if there were compulsion to bring things up to current standards (which, of course, is the case in some walks of life). However, so long as there is no compulsion to effect any improvements at all, it would seem (to me) to be reasonably logical for changes 'in the right direction' to be accepted, even if they didn't come up to current standards.

Kind Regards, John