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

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.

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.

Richard.
http://www.rtrussell.co.uk/