I want to fit a socket on an exterior wall of my house for car vacuuming, etc. Leaving Part P aside, would it be ok to break into an existing ring, fit a fused spur and run a cable through the wall to the socket as a radial circuit? The socket of course would be IP66 with an integral RCD.
Sounds good. Probably want to use a switched FCU, so there isn't power available outside to all passers-by ...
Oh yes, I would certainly do that. It would only be live when we were out there doing something.
Yup - basically. You would ideally need a double pole isolation switch inside to allow it to be turned off, and also to electrically remove it from the system should it introduce a trip problem to the house in wet weather etc.
Note if the circuit you feed it from already has an RCD protecting it, you will derive no extra benefit from a second one (and they don't discriminate either - so if an event happens that cause a trip, any combination of one or both tripping could be the result)
Full details of all the wrinkles:
Thanks for that, John. The existing circuit is fed from an RCD protected circuit, so dispensing the the integral RCD type will save me a few quid.
If you had needed an RCD, my recommendation is to fit this separately inside. RCDs and outdoor condensation don't mix.
Before I had a CU with RCD, I used a RCD spur to feed a single outside socket.
+1
The RCD then also protects the cable going out through the wall.
I've got several PowerBreaker H92s for outside sockets, pond electrics, etc. [Mine are an earlier model, and look a bit different - but do the same job]
It's easy to switch them off, simply by pressing the Test button. AIUI, this then breaks both live and neutral.
Yup - if only someone made a normal flush type, even if it did need a deeper box.
On Monday 11 February 2013 11:20 Farmer Giles wrote in uk.d-i-y:
Absolutely fine :)
Even easier - buy a kit -
Is that correct? I thought this was solved by having 'slow' and 'fast' trip RCDs so that the appropriate one blows first. Maybe that's only done to separate the 'whole house' RCD from the 'individual circuit' ones.
Robert
On Tuesday 12 February 2013 09:45 RobertL wrote in uk.d-i-y:
Yes - it's completely randome which one trips - probably both as they will have seen the current imbalance and started their trip sequence anyway.
The "fast trip" are 40mS (ie the "standard" RCD) and are the slowest permitted by the regs for the purposes of protecting someone who comes into contact with a live.
I am not aware of an RCD that can trip faster than 40mS.
The "slow type" you speak of are Type S Time delayed and are for use with TT (earth rod) installations and their purpose is protecting the cable against I2t (energy) overload in the event of a L-E fault. They do not offer suitable protection to people touching the live.
Yup.
You can do this in some cases, but the "slow" RCD (aka Type S or time delayed) is not appropriate for protection against direct contact - so you could not use it to protect a socket circuit. So you are reduced to a normal speed 30mA trip RCD at the circuit origin, which leaves no scope to have a faster RCD downstream.
Yup - common in TT installs.
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