Would I need to upgrade to current regs?

[EddyP]

Evening guys,

I've got a consumer unit installed in a barn, it's a metal casing but has a plastic front. I'm planning to add a couple of circuits in the barn and also change the 6mm twin and earth on the catenary that's currently feeding the barn to an SWA that runs underground, RCD protected rather than just an MCB like the existing setup.
I will be having a proper guy do the final connections for me so it's all above board, I'm just doing the leg work to help with costs.

In doing this work though will I have to bring the CU up to current regs and change it for an all metal unit?

Thanks

Ed.

 

[Iggifer]

Unless you're living in the barn, I don't think Amendment 3 applies to you.

However, if you're doing that much work, including adding RCD protection, you may as well change it for a new board.

 

[EddyP]

Not living in it no, it'll be a workshop.
Nothing wrong with the current board apart from a plastic front, it's a fairly big board though so would rather not change it unless really needed.

 

[Iggifer]

How far from your house is the barn?

 

[EddyP]

Its about 10 or 15m, think the 10mm SWA I've run through was 20m long.

 

[ban-all-sheds]

I will be having a proper guy do the final connections for me so it's all above board, I'm just doing the leg work to help with costs.

Are you doing it with his full agreement, supervision and direction?

Why has he said that an RCD is needed at the source of the sub-main supplying the barn?

Were you clear with Building Control about how the work would be done when you applied for Building Regulations approval?

In doing this work though will I have to bring the CU up to current regs and change it for an all metal unit?

No, because it's already there, it's not a new one being installed.

If you are having any new concealed cables or any new sockets in the bar, they will need RCD protection, but RCBOs could be the best way to do that if the board there doesn't have an RCD.

The switchfuse at the house will have to be "non-combustible". One made out of unicorn horn will do.

Not living in it no, it'll be a workshop.

Will it be OK to schlep back to the house to reset the RCD if it trips?

The barn has, or will have, emergency lighting, right?

 

[ban-all-sheds]

Unless you're living in the barn, I don't think Amendment 3 applies to you.

You don't have to actually live in a building for it to be "domestic" premises.

 

[Iggifer]

True, I was more tying to ascertain whether it was a working barn or more of a barn conversion.

And I read it to be adding RCD protection to final circuits in the barn, not RCD protection feeding the SWA - if the latter is the case, he needs a new electrician

 

[EddyP]

The electrician suggested I should protect the cable going out to the barn with a 100mA RCD, this is due to the 10mm T&E that's running in an internal wall in the house down to a JB where it connects to the SWA, it then exits the house, and goes underground to the barn.
The RCD in the barn will then be a 30mA so that it would trip first.
I do have some maintained fittings that I could put in the barn if I really need to.

 

[ban-all-sheds]

The electrician suggested I should protect the cable going out to the barn with a 100mA RCD, this is due to the 10mm T&E that's running in an internal wall in the house down to a JB where it connects to the SWA,

As Iggifer said, you need a new electrician - yours is badly broken. A 100mA RCD does not comply with the requirements for protection of concealed cables. That he doesn't know that is horrific, and would make me question whether he really is an electrician.

The RCD in the barn will then be a 30mA so that it would trip first.

No guarantee of that unless you go from bad to worse and make the one at the house end a time delayed one.

I do have some maintained fittings that I could put in the barn if I really need to.

If you really need to.

Well - I guess you know best - you know whether or not it would be OK to find yourself in a workshop, using power tools or other machinery, and to suddenly be plunged into darkness.

 

[Spark123]

A normal 100mA RCD will not discriminate with a 30mA, you'll need a time delay (type S selective) 100mA and another method of protecting the concealled cable.

 

[ban-all-sheds]

At which point you have to question why you have an RCD there in the first place.

This soi disant electrician needs kicking into touch.

 

[EddyP]

Thanks for the replies.

I'll certainly go back and challenge the guy to see what his logic was.

How should I protect the cable in the wall? It's already buried under all of the lime plaster in a newly fitted kitchen so removing it and running in metal conduit or similar isn't really an option.
Should I have an RCD in the house and just MCBs in the barn?

Thanks BAS - I'll fit one of the maintained lights in the barn as you suggest

 

[ban-all-sheds]

How should I protect the cable in the wall? It's already buried under all of the lime plaster in a newly fitted kitchen so removing it and running in metal conduit or similar isn't really an option.

Shame that a bit of forward planning wasn't an option.

That buried cable has to be on a 30mA RCD - your only other option would be to not use it and have something else following a different route. Could the armoured cable be run elsewhere outside, and enter the house where the meter etc are?

If you end up with the RCD at the house there's not much point having another in the barn. Poor design, though, to have the entire barn on 1 RCD.

 

[EddyP]

How should I protect the cable in the wall? It's already buried under all of the lime plaster in a newly fitted kitchen so removing it and running in metal conduit or similar isn't really an option.

Shame that a bit of forward planning wasn't an option.

That buried cable has to be on a 30mA RCD - your only other option would be to not use it and have something else following a different route. Could the armoured cable be run elsewhere outside, and enter the house where the meter etc are?

If you end up with the RCD at the house there's not much point having another in the barn. Poor design, though, to have the entire barn on 1 RCD.

Well I thought I had planned it, by speaking to the electrican.....

Really don't want to run it down the outside of the house, as it would look awful, and it's a 16th century listed stone house, it would also run half way up the house in the middle of the front elevation so really not ideal.

Looks like I'll have to RCD protect it from the house.

Out of interest how does it work when people have a 13A RCD socket on a ring main that's already RCD protected? I've seen that quite a few times.