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Wiring a new bathroom light

Hi,

I have installed a new bathroom light. (changed from a 60w bulb to a 38w fluorescent) I have 2 cables coming into the light each containing a red, black and earth core.

My old light had the 2 reds connected to each other using chocolate block, the 2 earths to an earth terminal and each black to its own terminal. If I do the same with the new light it remains on permanently. I have swapped the blacks around and there is no change. (The instructions with the light states to connect the reds to live, black to neutral, and earths to earth terminal. This just trips the breaker.)

Can you help me - what have I done wrong? Thanks Ian

Reply to
Ian
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Part P ...

Almost certainly this is the last light on a radial circuit (or a spur off a radial circuit) and the two cables are (a) supply (b) switch.

Then you aren't doing the same ...

Your ceiling rose had 3 terms + earth, your new fitting probably only has 2 terminals + earth.

It would do, because you are shorting the supply through the switch.

You *probably* need to chocolate-block the two reds together and unconnected to anything else. The black from the switch (switched live) and the black from the supply (neutral) go to the L and N on the light. The earths all go to the earth terminal. The black from the switch

*should* have a piece of red sleeving on it to show it's a live.

If in doubt, get a competent electrician.

Owain

Reply to
Owain

It's _probably_

The light has 3 connections - Live, Neutral and earth. It hopefully also has an additional choc block connection that doesn't actually connect to a wire within the light.

You've got 6 cables. Presumably two outer cables each containing a red, a black and an earth.

Two earths connect together, and connect to the 'earth' on the new light.

Two reds connect together, and connect to the choc block connection in the new light that's the spare.

One of the blacks connects to the neutral of the new light. One connects to the live. If it doesn't indicate a specific live and neutral, it doesn't matter which way round. If the new fluro prefers live and neutral in specific positions, you ought to know which of the two mains cables is permanent live and which goes to the light switch... Which means you might need to test it...

But, if you don't know how to connect a light up, you probably shouldn't be doing this anyway.

(And it's now illegal, anyway, in a bathroom).

A.

Reply to
AJB

The electrician has used the black on one of the cables as the live feed from the switch to the light fitting.

Keep the two reds connected together, but place one of the blacks in the live terminal of the light fitting, and the other black to the neutral side on the light fitting.

If the fuse breaker trips off, then swap the blacks around.

The black used as the live feed should really have been marked with a piece of red sleeving to denote it as a live wire from the switch, but this is not normally done in real life.

Reply to
BigWallop

Unless of course you notify your local council's "building control dept" beforehand, and have them check the installation afterwards (for the princely sum of £75), but then if you don't tell them who's to know what you're doing in your own home?

(disclaimer: not that I advocate illegal activities of course, merely highlighting a point).

Reply to
Dark Angel

You failed to hire an electrician.

I'm all in favour of DIY electrics for those who understand the principles. Those who don't might find them less likely to burn down the house by bringing in professional help when the basic principles are not understood.

Christian.

Reply to
Christian McArdle

It's actually classed as changing like for like in this case, and so does not need to be notified to the BCO office.

If the OP was changing the wiring and the style and position of the light fitting, then the installation would need to be certified by a registered electrical company, or through the notification scheme now rallied in the Part P building regulation amendment. But he's not.

Reply to
BigWallop

Well I do it, and I'm alive.

Reply to
usenet

Really? It was my understanding that any electrical work undertaken in a Bathroom, or Kitchen, required notifying your local council?

Reply to
Dark Angel

Nothing of a swap like for like needs notified. It's only new installations and major alterations to existing wiring and fittings that need to be notified and certificated.

Reply to
BigWallop

What?

Reply to
BigWallop

Thanks for the reply. That is what I have done - much head scratching from me as to why it doesn't work... Time to call an electrician.

The light has 3 connections - Live, Neutral and earth. It hopefully also has an additional choc block connection that doesn't actually connect to a wire within the light.

You've got 6 cables. Presumably two outer cables each containing a red, a black and an earth.

Two earths connect together, and connect to the 'earth' on the new light.

Two reds connect together, and connect to the choc block connection in the new light that's the spare.

One of the blacks connects to the neutral of the new light. One connects to the live. If it doesn't indicate a specific live and neutral, it doesn't matter which way round. If the new fluro prefers live and neutral in specific positions, you ought to know which of the two mains cables is permanent live and which goes to the light switch... Which means you might need to test it...

But, if you don't know how to connect a light up, you probably shouldn't be doing this anyway.

(And it's now illegal, anyway, in a bathroom).

A.

Reply to
Ian

Thanks for the reply. I would hire an electrician if I was installing something from scratch, but changing like for like shouldn't be too much of a problem. In this case it seems to be a problem, so I will probably hire in an electrician to sort things out for me. If anyone has any other suggestions I will be all ears!

You failed to hire an electrician.

I'm all in favour of DIY electrics for those who understand the principles. Those who don't might find them less likely to burn down the house by bringing in professional help when the basic principles are not understood.

Christian.

Reply to
Ian

But he isnt changing like for like. He's replacing an incandescent holder for a flourescent fitting.

Reply to
<me9

It isn't difficult Ian, it's just wrong marking on the existing cables that's got you confused. One of the black wires is being used as a live feed from the switch to the light fitting, and this is normal.

All you need is the two black wires to the light fitting, and leave the red wires connected together in the choc-block. Connect the earth wires to the fitting as normal.

How it's been done is.

The live feed from the breaker has been taken directly to the switch via the choc-block.

The black wire has been taken from the switch to the light fitting as a continuation of the red wire, but it hasn't been marked properly as such.

The black wire from the light fitting goes back to the fuse box to finish the circuit.

So, as you see, it isn't difficult when it's broken down to its basic configuration really.

Reply to
BigWallop

But he's not changing the position of the fitting, or introducing any new wiring configurations into the scheme. The light fitting isn't of a hugely differing load to any other normal light fitting, and because it's of a different means of light production makes no difference in this either. It's classed as a swap like for like in this case.

Reply to
BigWallop

On Thu, 21 Jul 2005 14:18:19 GMT,it is alleged that "BigWallop" spake thusly in uk.d-i-y:

Just a thought here. The OP stated that if hooked up to both blacks, (which sounds correct to me given how we're all picturing the wiring) the light remains on _permanently_. Also that if connected with red-red, black-black etc, it blows the breaker. (this second is not surprising IF the switch is *on*, but shouldn't occur if it's off). I am wondering "shorted/broken switch maybe?".

Reply to
Chip

You're right, it shouldn't have been able to be stuck permanently on. Can't see any way that could happen except for a shorted switch.

Can the OP try a different switch?

Also, were the connections (choc strip etc.) definitely definitely not making contact through loose strands, via the metal casing etc?

Reply to
PC Paul

I mark the black switched live wire with a red sleeve, that's what.

Reply to
usenet

Well done!!! Here's a Coconut. And, could you close the door on your way out, please. :-)

Reply to
BigWallop

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