Garage to be protected by an RCD

[ash88]

Hi,

I am an industrial electrician and have been asked by a friend to do some work on their house. I would like some advice on RCD's.

I have been asked to install a light and a socket in a garden shed. I am planning to supply the shed via the garage which already has a supply from a 32a breaker (which i am going to replace with a 20a breaker) seen as though it is run in 2.5mm SWA.

The garage circuit is currently not protected via any kind of RCD / RCBO. However, somebody has previously installed an RCD next to the house consumer unit, and has routed the house sockets circuit through it.

Will the RCD previously installed for the house sockets interfere with an RCD if I put one in a 4 way consumer unit in the garage?

Cheers.

 

[GLENNSPARK]

rite...progress (at last)...now, any extranoius in that garage?

 

[worzol99]

http://img442.imageshack.us/img442/5835/20130414155600.jpg shows the separate RCD.

So it looks like im ok to install a 30mA RCD in the garage.

In the picture it shows a 80amp rcd, some chunky sockets they must be!

 

[stuartcourt]

this could be a tough night ash88 (get that regs book out)

 

[ipf]

Cheers ipf, thats why i mentioned my industrial experience in the first post... Need a bit of guidance

OK pal.
Correctly terminated (at both ends) 2.5 swa, no RCD req, with 20 amb c/b supply. Garage - con unit with 30ma RCD, 16 or 20 amp c/b for power, 6 amp for lights. Test and certify as req, job done. Good luck.
(as long as that tn-c-s system is all above board):icon14:

 

[ash88]

Glennsparks - the garage electrically is one light fitting and two double sockets. There are no structural steel-work or water / gas service parts in there.

worzol - house sockets protected by 32a breaker ;-)

 

[ipf]

In the picture it shows a 80amp rcd, some chunky sockets they must be!

True, but he's not installing the sockets. Easy to change for a 32amp, if he feels obliged

Edit: 32amp supply so OK

 

[Octopus]

True, but he's not installing the sockets. Easy to change for a 32amp, if he feels obliged

Edit: 32amp supply so OK

he is fitting a socket in the shed!

 

[ash88]

The garage / shed sockets will be protected by 20a in the house cu and 16a in the garage cu.

 

[ipf]

he is fitting a socket in the shed!

Not the existing ones though!

 

[GLENNSPARK]

The garage / shed sockets will be protected by 20a in the house cu and 16a in the garage cu.

no....the supply cable will be protected by the 20A OPD in the house....
your finals in the shed will be protected by the 16A OPD in the garage....together with additional protection (RCD)

 

[ash88]

Well yes the 20a in the house is there to protect the cable.

Thanks to everyone for clearing up the RCD questions.

 

[GLENNSPARK]

Well yes the 20a in the house is there to protect the cable.

Thanks to everyone for clearing up the RCD questions.

so you know what your doing now?..
if so crack on....

 

[ash88]

Yes im clear now thanks.

Back to motors and plc's tomorrow yipee!

For future reference, what if the system was a TT or TN-S?

 

[GLENNSPARK]

Yes im clear now thanks.

Back to motors and plc's tomorrow yipee!

For future reference, what if the system was a TT or TN-S?

TN-S you would treat the same....
TT would require an 100mA s type RCD top end...30mA bottom end

 

[ash88]

Ok cheers glennspark and everybody else.