garage supply rccd

[jaguar1]

Should i install the rccd at the consumer unit in the house , thus protecting the garage supply cable and the garage itself with a 2-way mcb unit in the garage for the lights and socket.

Or should i use an mcb in the house consumer unit to feed the garage and have a 2 -way unit in the garage with a built in rccd , only this way the garage supply cable would not have rccd protection.

Thanks.

 

[festa]

Id rcd it BEFORE it left the house.

 

[Stoday]

If you have an RCD to control the whole of your supply (because you don't have an adequate earth) you don't need an extra one for the garage.

If your garage has an external earth in it, such as a copper water pipe, then put an RCD before it leaves your house, as suggested, but install a separate earth at the garage. That is not an optimal method because:
If the RCB is triggered, you have to return to the house to reset it.
You don't want to lose both the power and lighting at the same time - you
may have a saw rotating when the light goes off & it continue to spin for
a secont or so.

Otherwise, use an RCBO in the garage to protect the socket. You don't need the remote RCB if you don't have an "extraneous" earth. RCBs protect portable appliances. They are not required for lighting circuits.

 

[jaguar1]

Or could i fit an rccd in both the house consumer unit and have one in the garage consumer unit as well ???

 

[Steve]

Or could i fit an rccd in both the house consumer unit and have one in the garage consumer unit as well ???

Why? Explain how TWO identical RCDs protecting the same load are better than one.

The norm / recommendation is to fit the RCD at the outhouse end. This way, if a trip occurs, you dont have to go back to the house to reset it. It also has the benefit of trips at the garage not taking out other circuits in the house.

 

[JohnD]

A 100mA Time-delayed RCD at the origin is a very handy thing to have, and downstream circuits with 30mA/30ms RCDs will trip first if the leakage is on a final circuit. Not everyone agrees with me but my view is that outside supplies are more prone to damage from spades and water penetration so I like to see the sub-main to the outbuilding on an RCD.

If your whole house is protected by an RCD because you do not have an adequate earth, it is likely that the main RCD is (should be) a time-delayed one, with one or more 30's to cover the sockets, shower and shed.

 

[Spark123]

Now I'm completely lost!!
I think Stoday was touching on TT systems? Exporting earths isn't really a reason to use an RCD, it's mainly sockets reasonably expected to supply portable equipment outdoors which require RCD protection. There are other times where RCDs are required, mainly to do with special locations. If there are any extraneous conductive parts in the garage they need to be main bonded, the requirements change with the supply type.
The supply cable from the house to the garage, if it runs underground, should have an earthed metallic sheath or be concentric. Unless the supply is from a TT system there isn't a requirement to have it on RCD protection.
If its supply isn't from a TT system an RCD or an RCBO on the socket circuit at the garage end is most likely the only one which requires RCD protection.
Some info on exporting earths: clicky