strange fusebox/light fitting problem
 

Hi

I was changing a light fitting and have run into an unexpected
difficulty. I don't know very much about electricity, but as it seemed
little more complicated than swapping the wires out of the ceiling from
going into piece of plastic into another, I thought I'd be okay.

Before taking off the old fitting I flicked the switch at the fusebox
for the downstairs lighting circuit, which seems to be turning off the
current in the wires (I've touched them and am not dead!).

However while attempting to connect the new fitting the main fuse
tripped, cutting all electricity to the house. I thought this was
just chance so I flipped the fuse back on turning on the electricity
(leaving the lighting circuit switched off). Again after a little bit
of fiddling the main fuse flipped.

I wonder what could cause this - I thought if the fuse controlling the
lighting circuit were switched off then there would be no electricity
in these wires so they shouldn't cause another fuse to flip. I wonder
if anyone has any idea what is going on. I have isolated the wires
with insulating cable and am leaving it well alone until I know why
this is happening!

Thanks!

strange fusebox/light fitting problem
 

wrote in message
oups.com...
Hi

I was changing a light fitting and have run into an unexpected
difficulty. I don't know very much about electricity, but as it seemed
little more complicated than swapping the wires out of the ceiling from
going into piece of plastic into another, I thought I'd be okay.

Don't mess if you don't know what you're doing! The common problem I used
to see was people taking a fitting down and ending up with two or three
mains cables poking out of the cieling. Then all they would do is connect
all the red ones up and all the black ones before changing to the current
colour coding. So each time the switch went ON it shorted out the mains
supply and blew the fuse. They forgot one cable might be used for the
switch wire and the other might have been a supply going to or coming from
another fitting.
It was funny as people would swear they never touched it or did a thing and
it worked perfectly before! At least you have admitted it, so it makes it
easier to fix.

strange fusebox/light fitting problem
 

ctl wrote:

wrote in message
oups.com...

Hi

I was changing a light fitting and have run into an unexpected
difficulty. I don't know very much about electricity, but as it seemed
little more complicated than swapping the wires out of the ceiling from
going into piece of plastic into another, I thought I'd be okay.


Don't mess if you don't know what you're doing! The common problem I used
to see was people taking a fitting down and ending up with two or three
mains cables poking out of the cieling. Then all they would do is connect

Not what is happeniong here by the sounds of it though...

I am with Owain on the Neutral to Earth short tripping a RCD suggestion.
Sometimes it is hard to avoid even whey you anticipate it and try not to!



--
Cheers,

John.

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strange fusebox/light fitting problem
 

John Rumm wrote:

I am with Owain on the Neutral to Earth short tripping a RCD suggestion.
Sometimes it is hard to avoid even whey you anticipate it and try not to!

RCD tripping doesnt mean you'll get bit or anything's live. Just leave
it switched off till you're done.

NT

strange fusebox/light fitting problem
 

RCD tripping doesnt mean you'll get bit or anything's live. Just leave
it switched off till you're done.

Indeed. You shouldn't work on a non-isolated circuit. Turning off an MCB
does NOT isolate a circuit. If you must work on a circuit with only the MCB
off, then treat it as live working.

Christian.

strange fusebox/light fitting problem
 

Christian McArdle wrote:
RCD tripping doesnt mean you'll get bit or anything's live. Just leave
it switched off till you're done.

Indeed. You shouldn't work on a non-isolated circuit. Turning off an MCB
does NOT isolate a circuit. If you must work on a circuit with only the MCB
off, then treat it as live working.

Christian.

I take a neutral position on that one, being a down to earth kinda
person.

NT