Enclosure for 30ma rcd

ricky2609 · Jul 11, 2017

Been out to a property to price up repair on a couple of little bits with an old wylex board which has a 100ma RCD main switch. If I was to fit an upfront 30ma rcd before the main board would it have to be in a metal enclosure, haven't needed to do this before and not sure if enclosure would have to be metal or plastic

Thanks

Andy78 · Jul 11, 2017

If you were to fit one RCD to cover the whole installation then it would not be compliant.

ricky2609 · Jul 11, 2017

I advised a board change would be better but as this is a rental property & landlord does not want to spend would it not be better to make it safer with a 30ma rcd first

Andy78 · Jul 11, 2017

ricky2609 said:
I advised a board change would be better but as this is a rental property & landlord does not want to spend would it not be better to make it safer with a 30ma rcd first

It may be safer it terms of increased protection against shock, but may be less safe in the event of a fault due to a complete loss of power. That's why there are regulations to prevent the action you are considering.

davesparks · Jul 11, 2017

ricky2609 said:
I advised a board change would be better but as this is a rental property & landlord does not want to spend would it not be better to make it safer with a 30ma rcd first

There is no regulation which allows you to ignore the other regulations when your customer wants to do a job on the cheap.
If the customer won't pay for the job to be done properly then turn the job down.

westward10 · Jul 11, 2017

You haven't stated the repairs you are undertaking.

ricky2609 · Jul 11, 2017

westward10 said:
You haven't stated the repairs you are undertaking.

No just looking for an option to make install safer before I do anything

westward10 · Jul 11, 2017

What are you doing.

ricky2609 · Jul 11, 2017

westward10 said:
What are you doing.

replace some broken sockets & faulty cooker switch, moving a 240v fan out of zone 1 take down some old lights and replace with pendants

westward10 · Jul 11, 2017

Some of that can be deemed maintenance but if you are moving the fan then additional rcd protection will be required, is it not suitable for use in zone 1.

ricky2609 · Jul 11, 2017

westward10 said:
Some of that can be deemed maintenance but if you are moving the fan then additional rcd protection will be required, is it not suitable for use in zone 1.

I can't verify for sure so advised him to move or change to 12v, as it's vented via attic through celing easy enough to move

Ian1981 · Jul 12, 2017

ricky2609 said:
Been out to a property to price up repair on a couple of little bits with an old wylex board which has a 100ma RCD main switch. If I was to fit an upfront 30ma rcd before the main board would it have to be in a metal enclosure, haven't needed to do this before and not sure if enclosure would have to be metal or plastic

Thanks

The guidance on this I was given is a plastic enclosure is acceptable as it doesn't fall into the category of similar switch gear assemblies as a consumer unit would.
Bit of a grey area still I think but the guidance seems to be that if it was TT you can have a upfront time delay 100mA in a plastic enclosure before entering a metal consumer unit.

Change the consumer unit tho rather than fit an upfront rcd protecting the whole installation

westward10 · Jul 12, 2017

Who gave such advice.

Ian1981 · Jul 12, 2017

Similar switchgear assemblies

The phrase ‘similar switchgear assemblies’ in Regulation 421.1.201 means assemblies used for the same fundamental application as a consumer unit. A consumer unit is defined in Part 2 of BS 7671 as: ‘Consumer unit (may also be known as a consumer control unit or electricity control unit). A particular type of distribution board comprising a type-tested co-ordinated assembly for the control and distribution of electrical energy, principally in domestic premises, incorporating manual means of double-pole isolation on the incoming circuit(s) and an assembly of one or more fuses, circuit-breakers, residual current operated devices or signalling and other devices proven during the type-test of the assembly as suitable for such use.’

An example of a similar switchgear assembly is a three phase distribution board intended to be operated by ordinary persons. This would have to have isolation that interrupts the three incoming line conductors and the neutral, rather than just double-pole isolation as mentioned in the above definition.

Was sent to me via email from our QS whom sought guidance on the matter.

So depends if you think a stand alone rcd fits the bill.

westward10 · Jul 12, 2017

What is all this fuss then about separate rcd enclosures on TT not being permitted, not my words unless in metal enclosure.

Ian1981 · Jul 12, 2017

westward10 said:
What is all this fuss then about separate rcd enclosures on TT not being permitted, not my words unless in metal enclosure.

I know wylex brought out an installation guide via YouTube when the new regulation came in about non combustible consumer units in which they brought out an s type 100mA rcd unit to fit into a plastic enclosure for use on TT installations.
Think the on site guide mentions an upfront time delay as an option as well as class 2 glands where the tails enter the consumer unit I'd have to check that tho.

ricky2609 · Jul 12, 2017

Ian1981 said:
The guidance on this I was given is a plastic enclosure is acceptable as it doesn't fall into the category of similar switch gear assemblies as a consumer unit would.
Bit of a grey area still I think but the guidance seems to be that if it was TT you can have a upfront time delay 100mA in a plastic enclosure before entering a metal consumer unit.

Change the consumer unit tho rather than fit an upfront rcd protecting the whole installation

Thanks for the advice Ian, I haven't needed to do this before and probably won't again but landlord didn't want to spend on a board change and that's why I posted for advice, I fully understand a single rcd protecting the whole install is not ideal but I wanted to make sure the install was safer and would rather not have lost the job, I did speak with napit technical this morning explained everything i was doing and he said as I wasn't making any additions or alterations I didn't need to do anything about the main switch being 100ma but if I did put an upfront rcd in I wasn't making the install any less safe.

ricky2609 · Jul 12, 2017

Ian1981 said:
The guidance on this I was given is a plastic enclosure is acceptable as it doesn't fall into the category of similar switch gear assemblies as a consumer unit would.
Bit of a grey area still I think but the guidance seems to be that if it was TT you can have a upfront time delay 100mA in a plastic enclosure before entering a metal consumer unit.

Change the consumer unit tho rather than fit an upfront rcd protecting the whole installation

Thanks for the advice Ian, I haven't needed to do this before and probably won't again but landlord didn't want to spend on a board change and that's why I posted for advice, I fully understand a single rcd protecting the whole install is not ideal but I wanted to make sure the install was safer and would rather not have lost the job, I did speak with napit technical this morning explained everything i was doing and he said as I wasn't making any additions or alterations I didn't need to do anything about the main switch being 100ma but if I did put an upfront rcd in I wasn't making the install any less safe.

telectrix · Jul 12, 2017

bit of work with a jigsaw needed. amd. 3 compliant.

[ElectriciansForums.net] Enclosure for 30ma rcd

westward10 · Jul 12, 2017

Ian1981 said:
I know wylex brought out an installation guide via YouTube when the new regulation came in about non combustible consumer units in which they brought out an s type 100mA rcd unit to fit into a plastic enclosure for use on TT installations.
Think the on site guide mentions an upfront time delay as an option as well as class 2 glands where the tails enter the consumer unit I'd have to check that tho.

Not disagreeing Ian in fact the opposite because there was such an issue about this when Amm.3 came out about giving tails fault protection with the separate rcd issue.

Ian1981 · Jul 12, 2017

What was napit technicals view on placing the rcd in a non combustible enclosure or was it not mentioned?

Ian1981 · Jul 12, 2017

westward10 said:
Not disagreeing Ian in fact the opposite because there was such an issue about this when Amm.3 came out about giving tails fault protection with the separate rcd issue.

The opposite!!
Think I need a lay down

westward10 · Jul 12, 2017

See what I have done there, too late to edit

ChrisElectrical88 · Jul 13, 2017

As stated earlier most of it can go down as maintenance work, the fan however will need RCD protection, can you not just add a 30mA RCBO to this circuit instead of the whole installation?