Wiring up new wallights in the early hours the other night and managed
to wire the earth on the wall light into the live feed and the " live
" cable on the wallight into earth !.. I do sort of have an excuse as
it was about 1.00 am, i was knackered and do feel a complete arse!
the first light worked fine and the live feed to the 2nd light (where
i made the mixup) is taken from the chokblock at the connection behind
the 1st light.
I thought this would have tripped the circuit breaker at the unit when
i flicked on the switch ?
Any pointers...Honest..I do normally know what I'm doing!
On 18 Feb 2004 05:25:15 -0800, email@example.com (Ged) wrote:
It would only have tripped if you shorted out the live and earth, you
didn't, you just got them the wrong way round. An MCB can't tell what
colour wires you've connected it to, it's not that clever.
Why should it? The live potential you're feeding to the lamp down the
earth wire is going nowhere - you've made the outer casing of the second
light live, but there's nowhere much for the electricity to flow. Brickwork
has a pretty high resistance, and the nearest metallic route back to the
installation earth would be through the red-insulated wire, which is just
connected to one terminal of the lamp. Now, if you *touch* that outer casing,
you'll find out how much lower your body+shoes+floorboards etc. resistance
is than the brickwork/plasterboard (not sure if your wall lights are inside
a room or outdoor 'security' lights): but even then the current, whilst
painful and just-possibly fatal (much more so if outside, barefooted, etc.
than indoors, carpeted etc), will be much too small to trip a 6A lighting
If you'd had a earth-leakage breaker in the circuit, it might have tripped
as a result of the earth-to-neutral connection through the lamp in the
miswired fitting (provides alternative path for neutral current so
triggering the current-imbalance detector), or when touching the metalwork
you'd made live. But (as often pointed out in this group) the 'can't see
where I'm going in the dark' risk of putting indoor lighting circuits on
an earth-leakage breaker exceeds the electrocution risk.
So, now you'll know better still - you'll know to double- and triple-check
your connections before restoring power, and maybe not to do safety-critical
work in the wee small hours ;-) Never run with scissors, always cut so the
blade goes *away* from you, measure-twice-cut-once, make sure you have clean
underwear in case you're run over by a bus, don't carry hot drinks up the
stairs (only one of these pieces of advice comes from an employer's
helf-n-safetee brigade: can you guess which one?)
HTH - Stefek
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