Simple light fitting fail

[greycarsdave]

Hi,

I'm fairly competent with simple household electrics, swapping things, adding a light or socket, but what appeared to be a simple swap has made me rethink my electrical abilities!

The old fitting was a simple bayonet lampholder, wiring shown below: 2 black cables into the fitting, 2 reds terminated, 2 earth's sheathed.

I believed that the 2 blacks would be switched live, and neutral. I tested, probably poorly, for the switched live, thought I had it. Wired that to the L of the new fitting, as shown. The other black to N, and the earth to E. The new fitting is a basic LED ceiling light if that helps. It is not a dimmer switch.

Turned the electric back on, when I switched the light on, buzzing and flickering from I believe both the fitting and the switch. Quickly turning it off, and believing I had made a mistake, I switched the L and N. Electric on, switch on, same if not worse flickering/ buzzing.

Put the old fitting back on, and works fine.

Any ideas or is it professional time?

Thanks, Dave

 

[chivers67]

There's nothing obvious that you've done anything wrong, especially if the old fitting works. The choc block does look like it's heated up somehow - check that in the first instance and then the switch

Can you get a piece of flex & wire the light(s) into it and attached a plug on the other end ... plug that in to see it the lights work ok?

 

[EFLImpudence]

I would agree with your summary.

Many an hour wasted over faulty new products.

 

[greycarsdave]

The fitting is new, but I guess that's definitely a possibility. I'll try a replacement

 

[greycarsdave]

Thanks for the replies

 

[terryplumb]

Looks like there is a slit in the insulation of one of the black wires,and one of the reds has a mark on it too. The connector block is decidedly dodgy ! Was it like that on the original fitting ?
Did any fuses blow or breakers trip ?

 

[greycarsdave]

All the nicks, and the melted block were in the original fitting, which looks to be at least 20 years old, if not more. No fuses blew, and the MCB remained on. The buzzing and flickering made me switch the light off quickly. Thanks, Dave.

 

[oldbutnotdead]

Check the fitting out first. Then give the copper cores of all the wires a good tug with a set of pliers just to make sure there isn't a random air gap in there (they look very twisty)

 

[SUNRAY]

I would agree with your summary.

Many an hour wasted over faulty new products.

Oh yes. Many many years ago I wired a newbuild property, fitted a bulb in every holder and checked operation. Neither bulb lit and spent 10 minutes with a meter chasing the hall/landing 2 way + intermediate wiring.
The fact that both bulbs were faulty took me right away from checking them.

 

[markyd1]

All the nicks, and the melted block were in the original fitting, which looks to be at least 20 years old, if not more. No fuses blew, and the MCB remained on. The buzzing and flickering made me switch the light off quickly. Thanks, Dave.

Oh well Thats alright then.........NOT

 

[securespark]

When you reconnected the old fitting that worked fine, did you connect the blacks across the lamp, the reds to each other and the two earth conductors likewise?

 

[securespark]

Oh yes. Many many years ago I wired a newbuild property, fitted a bulb in every holder and checked operation. Neither bulb lit and spent 10 minutes with a meter chasing the hall/landing 2 way + intermediate wiring.
The fact that both bulbs were faulty took me right away from checking them.

About 12 years ago, I fitted a brand new Wylex twin RCD board.

We used to get them direct from Electrium and this one was really "fresh".

But both RCDs were fubarred out of the box!

 

[securespark]

Suspect the reds are badly connected. The crackling will be the circuit arcing.

Turn off all power and check for dead.

Reconnect the reds securely in a new connector.

While you're at it, use your multimeter to identify which black is the switched live, and mark it accordingly.

If after reconnecting the supply, the fitting is still inop, then I would swap it.

 

[greycarsdave]

Thanks for your replies securespark. The shown wiring is exactly how it came out of the old lampholder. The earth's, and reds remained unchanged from old to new and vice versa. While I wouldn't be happy keeping the wires as they were with nicks and a melted connector, I tested the new fitting expecting to come back and clean up the wiring.

I'll do all these little bits, test properly, and hope this fitting works. I have another replacement ready just in case, and I'll flex test the first one if it fails again for interest.

Many thanks for all the replies, Dave.