BAFFLING smoke alarm problem

[davesparks]

what have you done so far to try and identify the problem? What tests have you carried out and what were the results?
In my opinion the symptoms suggest a series connection of loads when they should be in parallel, so would probably measure the potential across each load and at each point wrt earth.

 

[SeanSparky]

No I'm not at the job now, I'll be back tomorrow to sort it out.

Can you post pics of all three connections.

 

[davesparks]

Even works with just 1 detector plugged in so my best guess is it's something to do with the 3core, most likely the interlink core ??

Guessing? Are you a plumber?

 

[SeanSparky]

They are both BRK brand supplied by the customer.
The dead tests show nothing out of the ordinary.

What make of smokes?

What dead tests did you do?

 

[SeanSparky]

This has crossed my mind also but I'm assuming All BRK brand detectors should be able to interlink
Can't find anything online

If all else fails, I recall a thing about smoke and heat not always compatible for interlinking (hopefully not imagined) - perhaps try removing interlink to heat and see if it changes behaviour?

 

[SeanSparky]

Yes

Guessing? Are you a plumber?

 

[SeanSparky]

Yes

Guessing? Are you a plumber?

 

[Midwest]

That's the standard pendant light, Swithed live, N, and loop,
I've jumped off the loop, N and earth

If the 'standard pendant' has been connected & wired by someone else, are you sure that has been correctly wired up? If not, and the sw L, lives, and neutrals have been mixed up, adding the loads (smokes), could present voltage at the neutral of the light when its switched on.

Edit; previously incorrectly wired/connected pendant, would still illuminate when switched on, even though incorrectly connected.

 

[davesparks]

If the only thing that has changed is the addition of the smoke alarms then the only way I can see that they would cause this operation is if they are connected in parallel with the switch, and therefore in series with the light.
When the switch is closed the smoke alarms will be shorted out and when the switch is open they will be in series with the light.

 

[SeanSparky]

I've checked it, everything is correct

If the 'standard pendant' has been connected & wired by someone else, are you sure that has been correctly wired up? If not, and the sw L, lives, and neutrals have been mixed up, adding the loads (smokes), could present voltage at the neutral of the light when its switched on.

 

[davesparks]

I've checked it, everything is correct

Clearly not everything is correct as if it was then you wouldn't have a fault

 

[Midwest]

Well, I would suggest something isn't correct
Edit; ditto

 

[westward10]

Recheck the initial connections to ensure they are at the permanent line and neutral.

 

[SeanSparky]

But the same would happen with only 1 detector connected, but it only happens when both are connected

If the only thing that has changed is the addition of the smoke alarms then the only way I can see that they would cause this operation is if they are connected in parallel with the switch, and therefore in series with the light.
When the switch is closed the smoke alarms will be shorted out and when the switch is open they will be in series with the light.

 

[vjsmarwick]

my only question is what type of lamps are you using ? At a guess I'm thinking LED