Old wiring - Bathroom Light

Psully24 · 11-30-2007, 12:07 PM

Hi,

I'm putting in a halogen light in my bathroom which is on the old wiring system.

I have 2 black wires and 2 red with the earth wired to the fitting.

I put the 2 red wires to the live and the two black to the neutral and the earth was wired to the attached earth n the light.

The light comes on and when you switch it off it blows the circuit and all the lights go out in the house. If you try and switch the light off and reset the fuse it just blows, any ideas?

AllanJ · 11-30-2007, 01:57 PM

When you turned the switch "off", somehow another connection was made short circuiting a live wire to earth (ground) or to a neutral.

Did you make any changes at the switch?

Can you describe what everything looked like before you installed the new light or made any changes?

Specify how the individual wires were grouped into cables back inside the junction box where the new light is installed (and also where the switch is).

Psully24 · 11-30-2007, 02:31 PM

Hi alan,

I made no changes to the switch, its the standard pull string bathroom switch.

The previous light was the standard type light for standard bulb but the old wiring was two red wires to one point and the two black wires each to a seperate point and the earth to the fitting.

The only real difference is that I am also connecting both black wires to th same point on the new light

Stubbie · 11-30-2007, 03:03 PM

You don't mention any neutral (white wires) other than the fixture white. So can you tell us if the reds were attached to the old fixture and the blacks also attached to the old fixture? Is that what you meant by attached to points?... Points on the old fixture like under screws?
Second.... it would really helps us if you have a voltage tester...do you have one?

HouseHelper · 11-30-2007, 03:09 PM

It would also be helpful if you post where you are located. Your use of the term "earth" leads me to believe you are not in the USA.

Psully24 · 11-30-2007, 03:46 PM

I'm in the UK.

The only live wire is one of the reds, all the others hardly register with the tester.

frenchelectrican · 11-30-2007, 04:10 PM

I noticed that you are from UK and the wire colour you describing that is on the old electical colour code the red was used to be hot [ live ] and black for netural.

for current colour it will be bleu for netural and brown for hot and yes the black is hot as well.[ used on 3Ø system]

the earth is always either bare or green with yellow stripe.

i really suggest to run the voltage tester on one leg between the hot leg and earth then do the same with other because over the time they { UK } did change the colour code at least few time over the years.

{ O.T. i used live in France so i know we have our own mess as well we have 3 diffrent colours codes and you really have to watch what ya hook up with it other wise you will say this word

}

Merci, Marc

Stubbie · 11-30-2007, 04:27 PM

Ok that explains a lot. This is a USA site so you see the confusion. In the UK black is neutral and red hot as mark said. What I actually think is happening is you are really turning the fixture on not off. And you are completing a short to ground or neutral. My best guess is you have wiring error at the fixture. I have an idea what is wrong....open up your switch box on the wall (it would appear you have one) and tell me what color wires are connected to the switch.

I believe you will find a black wire connected to the switch and a red wire connected to the switch.

On the old fixture you had a terminal that acted as a connector for the wires only. It didnt have any connection to the switched hot of the fixture. This is where the reds connected. The blacks connected to two different points because one of them is the switched hot from the switch and one is the neutral. what I think you need to do is connect the two reds together and not to the fixture that is why your fixture is "on" because you have the incoming hot "red" wire connected to the fixture switched hot making the fixture "always on" because it is bypassing the switch. When you pull your pull string you are actually turning the fixture on and since one of the black wires is really the switched hot and the other is the neutral and you have them connected together at the light fixture you are completing a short circuit to the neutral wire when you turn 'on your light.

This is what you have now.......I think..... you need to connect the reds together but not at the fixture, connect the switched hot black to where you now have the reds connected leave the black neutral where it is and earth where it is.

The correct wiring is the second image but you have something similar to this going on with the way you wired the new halogen whether you have a wall switch or not.

frenchelectrican · 11-30-2007, 05:07 PM

Quote:

Originally Posted by Psully24

Hi alan,

I made no changes to the switch, its the standard pull string bathroom switch.

The previous light was the standard type light for standard bulb but the old wiring was two red wires to one point and the two black wires each to a seperate point and the earth to the fitting.

The only real difference is that I am also connecting both black wires to th same point on the new light

i think i know why when you put in new halogen luminaire did that new luminaire did have pull switch or not ?? if not is there a switch on the wall either inside or outside of the bathroom wall ??

second thing the reason why i repost it insteading of reediting the whole thing you have black wire at seprated points so iam supecting one of them is a switch loop that is a give away signal.

so please recheck the connections again.
if this lighting circuit is serve other luminaires as well in other rooms ?? if not you may have to look for the switch somehwhere in the area.

Merci, Marc

Stubbie · 11-30-2007, 05:32 PM

Yes, marc is correct you may have a wall switch which is what I was refering to by opening up the switch box.....not the pull switch....sorry if that confused you. But your wiring suggests a wall switch that controls the power to the pull switch and light.

Stubbie · 11-30-2007, 05:41 PM

Marc

I have been looking at Uk fixtures from the old wiring system they had....they have connections at the fixture to just join wires... and connections to the light for hot and neutral sorta like a terminal strip would have. I think this new halogen doesn't have that kind of set up. Just connections for the light.

frenchelectrican · 12-01-2007, 01:20 AM

Hello Stubbie:,,

Yes i did read your reply related to the switching issue and it was pretty common with older UK wiring that time the switch is located outside of the bathroom due the code regulations they used to be very strict that time but right now i belive currentally now they are allowed to put the switch inside the bathroom.

and you got the drawing correct and that will expain it more clearer with the details there.

I know The French electrical codes did disallowed before but now allowed as long it is RCD'ed [ GFCI ]

Merci, Marc