wiring up to outside light

[Burlington Bertie]

I'm looking at the options for wiring my greenhouse. There's a dusk to dawn light nearby which comes off the consumer unit in 2.5 mm power cable which goes into a weatherproof box then out to the light.

The main trip out on this circuit is rated at 6 amps, but if I upped this to 20 amps like the main power circuits would this be OK? I'm trying to avoid extra underground or overhead cabling.

I also have to consider the RCD. My lighting circuits don't seem to be connected to this device. Should they be?

[Piers James]

I believe that would be OK, but I also think you would have to wire the light into an FCU spurred off the "new" power circuit.

Technically, you shouldn't be doing it at all because electrical work outside falls under the new regs requiring a competent bod to do it.

[cynic]

No

I'm

If the job is worth doing its worth doing right. Based on your questions you should leave well alone and get someone in who knows how to do it properly.

No

[Andrew Gabriel]

What load are you expecting to use in the greenhouse? How long is the existing cable run?

Generally, not. It's considered a bad idea for indoor lighting. Inside a greenhouse, there would be an argument for it.

[Andy Hall]

The choices if one wants to play by the book are to

- Employ an electrician being a member of an approved trade organisation and able to test and self certify his work

- Do the work under the framework of a Building Notice with the local authority

There remains the option of not playing by the book.

[Dave]

No! The 'main trip' is there to protect the cable. If the trip is a 6 Amp one, then the cable can not be rated at a higher level, unless it is changed for a larger cross sectional size.

Dave

[Andy Wade]

In this case, I have to agree. Strongly.

[Burlington Bertie]

OK I agree I shouldn't go into this without some prior knowledge, hence the question. This is a DIY group so presumably we have folks who do their own wiring who are not professional electricians.

I know what I have to do now. Thanks everybody.