Plastic RCD sockets in metal box?

[raybarrow]

Hi Folks,

Bit of a follow on from query about RCD adapters - now sorted.
In the garage There is a metal RCD 2 gang socket (not working). It's fixed right up against the CU and I was concerned about it having short tails if I try to replace it like for like. I've had the faceplate off for a look and and the tails are a good length.
However I tried to find an active (used it for power tools) metal innards in seveal DIY sheds. I can get non-RCD stuff in a dozen different colours in plastic but bog standard metal RCD faceplates there are non.
I would have thought the Ative RCD innards would be cheaper than the Passive ones but no, they are expensive.
Question: Can I fit a plastic innards to a metal box? Or is that a big No! No!
Question can I replace the metal RCD innnards with a non-RCD metal innards?
The CU has RCD protection.

Cheers,
Ray.

[csearle]

Hi Folks,

Hi Ray, not totally sure what you mean by plastic innards and metal innards.

If your consumer unit has 30mA RCD protection on the circuit which is supplying your defunct socket outlet then there is no need for that socket outlet also to have its own RCD¹. You could replace it with a non-RCD one. You would need to make sure that this is the case though. Some circuits might not be protected by the RCD; you'd need to establish this.

Socket outlets in garages are often metal-clad simply to protect them from impact in that environment. If you feel that such extra impact protection is not required then the socket outlet could be replaced with a standard non-metal-clad one.

It is not pretty but there is nothing stopping you putting a standard socket outlet on the back-box of a metal-clad socket outlet providing the earth lug of the back-box has been connected (which it should be already). There might not be enough room for it though if the back box is very close to the consumer unit².

Chris
¹ If the RCD in the consumer unit is a 100mA one then the socket outlet would have to be further protected by a 30mA RCD.
² You could replace the metal back-box with a pattress, which should be the same size as the socket outlet, so able to be butted up to the consumer unit.

[raybarrow]

OK, further investigation reveals:
House rewired 2007. CU left to right 30mA RCD labelled RCD Controlled circuits RCCB Protected circuits 63A 30mA230V EN61008
Shower in bathroom B40
Sockets upstairs B32
Sockets downstairs B32
Sockets kitchen B32
Shower downstairs B40
Lighting unreadable B16
Smoke Alarms B06
Lighting Downstairs B06
Lighting Upstairs B06
Garage sockets B32
Main switch 100A For all circuits Not To Exceed Switching rating of 100A

When I test the RCD the power goes of from the Shower in the bathroom down to and including the shower downstairs.
The smoke alarms, lighting and garage stay on. I undid the RCD socket and tested with a mains tester on the wiring connected to the socket. It definitely has power even when the RCD in the CU has been triped to off. The garage sockets are this non working RCD socket and the freezer socket (this has the 'T' shaped earth pin). I suppose this done to protect the freezer if the RCD in CU trips whilst we are away?

I see my options are:
Ignore it - we are planning to move anyway (probably not a great option.)
Pay someone to fit a new RCD socket - most expensive but safest option
Fit a new RCD socket myself - Next expensive option. Now I've sussed out the wiring I'm ok doing that
Fit a non-RCD socket - cheapest option

Any comments,
Ray.

[GrahamPlatt]

Misread sockets as rockets and wondered what the devil?
But as it’s sockets, as you were.

[csearle]

OK, further investigation reveals:
House rewired 2007. CU left to right 30mA RCD labelled RCD Controlled circuits RCCB Protected circuits 63A 30mA230V EN61008
Shower in bathroom B40
Sockets upstairs B32
Sockets downstairs B32
Sockets kitchen B32
Shower downstairs B40
Lighting unreadable B16
Smoke Alarms B06
Lighting Downstairs B06
Lighting Upstairs B06
Garage sockets B32
Main switch 100A For all circuits Not To Exceed Switching rating of 100A

When I test the RCD the power goes of from the Shower in the bathroom down to and including the shower downstairs.
The smoke alarms, lighting and garage stay on. I undid the RCD socket and tested with a mains tester on the wiring connected to the socket. It definitely has power even when the RCD in the CU has been triped to off. The garage sockets are this non working RCD socket and the freezer socket (this has the 'T' shaped earth pin). I suppose this done to protect the freezer if the RCD in CU trips whilst we are away?

I see my options are:
Ignore it - we are planning to move anyway (probably not a great option.)
Pay someone to fit a new RCD socket - most expensive but safest option
Fit a new RCD socket myself - Next expensive option. Now I've sussed out the wiring I'm ok doing that
Fit a non-RCD socket - cheapest option

Any comments,

Thanks Ray. Yes the circuits from Shower in bathroom B40 to Shower downstairs B40 are probably the ones protected by the RCD. (Nowadays pretty much all circuits have to be thusly protected, but there is no obligation to retrospectively upgrade unless a circuit addition is made.)

The remainder of the circuits will be unprotected. That is why the installer of the garage socket adjacent to the CU put in one with its own RCD protection. As you point out, the freezer is unprotected so that your food stays safe if the RCD trips whilst you are away.

Of your options:
Ignore it - we are planning to move anyway (probably not a great option.)
This is the cheapest option but the least convenient because you won't have a working socket outlet there.

Pay someone to fit a new RCD socket - most expensive but safest option
I agree.

Fit a new RCD socket myself - Next expensive option. Now I've sussed out the wiring I'm ok doing that
I think this is the cheapest and most satisfying option. Also quite safe if you turn off that circuit whilst you work on it. E.g. £18 at Screwfix so not super-expensive.

Fit a non-RCD socket - cheapest option
This is not an option you should choose because even as a DIYer you have an obligation to do the work competently, i.e. safely. Installing a replacement socket and removing the RCD protection is unsafe. Unsafe because anyone, also in the future, using that socket outlet should be protected from electric shock in the event of inadvertent direct contact with a live conductor or in the event of a person touching an Earthed enclosure just as a fault to Earth occurring anywhere in the electrical installation is cleared by the RCD and/or circuit breaker.

Chris

[jfgw]

A further option may be to fit a non-rcd socket and replace the mcb in the consumer unit with an rcbo. This would also protect the freezer socket and the exposed metalwork of the double socket.

Do you know what sort of earthing system you have?


Julian F. G. W.

[raybarrow]

Hi Chris,
I like the idea of the Screwfix (we have one 5 minutes away) £18 socket. I notice it is advertised as Passive. The current one is non-latching which seem to command a hefty price. There seems to a lot of confusion about the types. Is it ok to fit a Passive in place of the non-latching?

Hi Julian,
The house a 3 bed semi late 1930s so nothing special. Earth goes an earth block on the Meter Board and disappears behind the board so presuming whatever was normal for those houses. Anyway replaceing the socket, as Chris suggests, seems the less involved solution.

Thanks both,
Ray.

[pochisoldi]

Hi Chris,
I like the idea of the Screwfix (we have one 5 minutes away) £18 socket. I notice it is advertised as Passive. The current one is non-latching which seem to command a hefty price. There seems to a lot of confusion about the types. Is it ok to fit a Passive in place of the non-latching?

Hi Julian,
The house a 3 bed semi late 1930s so nothing special. Earth goes an earth block on the Meter Board and disappears behind the board so presuming whatever was normal for those houses. Anyway replaceing the socket, as Chris suggests, seems the less involved solution.

Thanks both,
Ray.

Passive/latching RCDs will not trip off when power is lost - ideal for a freezer, washing machine etc Not good when being used with shed/garage/garden tools where reapplication of power could result in things spinning in a dangerous manner...

[csearle]

Hi Chris,
I like the idea of the Screwfix (we have one 5 minutes away) £18 socket. I notice it is advertised as Passive. The current one is non-latching which seem to command a hefty price. There seems to a lot of confusion about the types. Is it ok to fit a Passive in place of the non-latching?

To my shame I had never appreciated the difference.

I think, notwithstanding the benefits of an "active" RCD effectively tripping upon a power cut, I'd be perfectly happy with the cheap one.

If you were to have a plain socket on a standard RCD within the consumer unit, as is often the case for outdoor sockets, you would find the socket became live again after the power cut, just like the cheap passive RCD.

Chris

[raybarrow]

Hi Folks,
RCD socket replaced, all working, nobody died.
Annoyingly new socket was a fraction of mm different in size to the existing back box. Managed to fit it securely though.
Now to move on to next little job prior to selling house.
Ray