RCD plug, info please

[ss]

I have just wired some electric to my shed just a plug at one end and a socket at the other only for very occassional use or the hedge timmer as it saves me running an extension cable from the house each time, it would also give me a light if I need anything over winter. I want to fit an RCD plug (for the supply of electric to the shed) but what is best bearing in mind it will hardly be used. A hardwired socket or just a plug in at the house wall socket end (would that do ok) Any ratings or other spec I should look out for. I wont use the trimmer when wet so this is just an additional precaution.

[meow2222]

I'd definitely get an RCD plug on that lead.

NT

[fred]

In article , ss writes

I think you are planning to protect the external lead rather than just protecting it from the shed end which is good.

IME RCD sockets are made to better standards than plug-in RCDs so they would be my choice (after a proper fixed wiring RCD installation) but for a per use installation I would have no problem using a plug-in RCD at the house end. I wouldn't use one for a reliable long term supply however (expect false trips easily within 30 days) so no use for long term external feeds such as greenhouse frost protection or a freezer in a shed.

No problem however if you just want temporary lights or power.

[Martin Bonner]

A plug at the house wall socket end would be safer (because it protects the lead as well as the stuff in the shed). If you plan to be tripping the RCD repeatedly, then it would be more convenient to have the RCD in the shed (so you can reset it easily).

+1

[Chris Holmes]

Could you give us some more info?

How are you currently planning to introduce the Plug to the electrics at the house end? Do you intend to leave it permenantly plugged in? Is the circuit to which you will be attachning it already protected by a 30mA RCD in the consummer unit? (If so adding another will not necessarily stop the "house" one tripping as well/instead, but may offer better protection for the lead)

Chris

[ARW]

Noting your points about RCD plugs and sockets then I would prefer to see the lead hard wired into a RCD fused spur in the house.

If you use an RCD socket and the RCD trips there is a chance that the user could then plug the lead into a non RCD socket.

I suggest that the OP needs a 30mA active RCD - the active RCD need resetting after a powercut but as there is no mention of a fridge freezer in the shed then that would not be a problem.

[ss]

By plugging into a wall socket

Only when required

Yes

[John Rumm]

In which case, there is no value in adding another one at the plug[1], since in the event of a low leakage current emanating from the shed feed, the house CU one will tend to trip first (it will see the same leakage as the one in the plug, plus any additional leakage from the house circuits and appliances). In the case of an earth fault at the shed, then both RCDs will see a trip current over their threshold, and it a straight race as to which trips first, with no way of predicting which combination of devices will trip.

[1] Assuming the house one trips at 30mA