Todays lighting puzzle

timhoward · Aug 24, 2022

Before I take it apart….
Anyone like to take any guesses?
Fitting a new (customer supplied) light fitting. Fitted, Came to a Zs test and oddness prevailed to the degree I wasn’t ready to leave it connected. In the end I bought it home for more testing.

Bulb holders 1 and 2

[ElectriciansForums.net] Todays lighting puzzle

Bulb holder 3

Same readings occurred when at customers house. Any guesses what I’ll find inside?

Pretty Mouth · Aug 25, 2022

High R/loose connection on the N for bulb holder 3?

timhoward · Aug 25, 2022

Pretty Mouth said:
High R/loose connection on the N for bulb holder 3?

Essentially yes. This was a bit silly - it turned out to be
a) Me not thinking completely straight when very tired (this was the 'quick and easy on the way home job!')
b) daft fitting design

They are ES fittings. It turns out that unless there's a bulb in bulb-holder 2, there is no N continuity to bulb-holder 3.
I happened to pick number 3 for first test, and did a double-take at the readings without remembering that's what it would look like with no N connection at all.
Then I took fitting down, got clear IR tests, and found there was no N connectivity. (All the time without moving test adaptor from position 3)
So I put the pendant back up and said I'd take it away and look at it.

( This design also means that if you have a working bulb in number 3 and are changing number 2, you can touch the side N contact and get full potential. )

UNG · Aug 25, 2022

timhoward said:
Essentially yes. This was a bit silly - it turned out to be
a) Me not thinking completely straight when very tired (this was the 'quick and easy on the way home job!')
b) daft fitting design

They are ES fittings. It turns out that unless there's a bulb in bulb-holder 2, there is no N continuity to bulb-holder 3.
I happened to pick number 3 for first test, and did a double-take at the readings without remembering that's what it would look like with no N connection at all.
Then I took fitting down, got clear IR tests, and found there was no N connectivity. (All the time without moving test adaptor from position 3)
So I put the pendant back up and said I'd take it away and look at it.

( This design also means that if you have a working bulb in number 3 and are changing number 2, you can touch the side N contact and get full potential. )

If all the lampholders are the same would that mean lampholder 2 is actually faulty and has evaded quality control at the manufacturers

If this is a customer supplied fitting I think I would suggest they returned the fitting for a replacement and then test the new fitting for the same issue

timhoward · Aug 25, 2022

Contacts: (no connection to 3rd one)

Number 2:

UNG said:
If all the lampholders are the same would that mean lampholder 2 is actually faulty and has evaded quality control at the manufacturers

I've had it apart. It's arranged as per diagram above.
There is no physical way one could get a wire to the 3rd isolated contact as it's entirely enclosed and I'm pretty sure this is the intended design.

UNG said:
If this is a customer supplied fitting I think I would suggest they returned the fitting for a replacement and then test the new fitting for the same issue

It's an expensive Polish-made fitting which is mechanically well made but totally let down by the 3-way cheap ES bulb-holder. I don't believe it's faulty. I've decided to tell the customer I'm not very impressed with it and will suggest a different fitting is used.
I have a feeling there is some sentimental attachment involved (she is Ukrainian) so it won't be an easy discussion.

I don't consider it any more dangerous than a BC fitting so don't think I should refuse to fit it outright.