On 19/06/2013 09:38, Richard Russell wrote:
On Wednesday, June 19, 2013 8:26:43 AM UTC+1, Tim Watts wrote:
"Only 115V"? I think you *should* worry about that - outside is a
particularly special case as you both have enhanced shock risk
(wet ground/rain/etc) *and* you are more likely to expose a member
of the public to risk (eg visitors).

I can't say I agree. AIUI, the requirement to have RCD protection at
all on garden lighting circuits is a fairly recent one.

Not especially no. Outside circuits in general require RCD protection.

In addition,
garden luminaires are far better protected from accidental contact
than a domestic (bayonet or screw) light fitting, because of the
weatherproofing requirement.

So lets say the cause of the fault is that you have a live to case
short on a lamp and the case is not earthed, and only under certain
circumstances is there enough leakage to earth to cause your trip. Still
fancy leaning against that lamp post with the RCD disabled?

To gain access to the bulb, let alone remove it to expose a live
terminal, typically requires unscrewing a watertight cover -
something which I know from experience is not easy even when you want
to do it! The idea that a visitor might unscrew one of these covers,
remove the bulb (presumably lit) and poke their finger into the
exposed socket - mostly GU10 so that's not easy - seems wildly
implausible to me.

Implausible yes, but not relevant either.

As it happens the point is moot anyway. As an experiment I bypassed
the RCD so I could power up the circuit for a few hours. The result
is that (maybe through some local heating drying out the moisture)
the leak is now reduced below the trip threshold and it's running
fine again with the RCD re-instated. The problem may recur, of
course, but I'll worry about that if and when it happens.

Ah, the ostrich algorithm ;-)


--
Cheers,

John.

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