Voltage at light fitting that is turned off

[topquark]

Sure just post away, there's always someone around.

 

[BillyTheSparks]

Limited choice on the packaging front. I'd probably go for this given your 2K2 Ohm choice: Buy High Power RESISTOR 50W 2K2 Vishay RCH50S22000JS06 online from RS for next day delivery.

Easy to solder some leads on for use and wrap in heatshrink for use. Should be easy enough to incorporate in the box(es).

Hi, I managed to get hold of these and they seemed better than the first lot I got hold of, I wired one up to a plugtop to see how hot they got. It lasted for about ten minutes, didn't get too hot, but then burnt it's self out.
Speaking to someone at the wholesaler and they have suggested that I could put an SES lampholder with a oven lamp in the ceiling void which will take the excess voltage out of the switch live.

Good Idea??

I'm not too sure. It would probably work but I dont fancy leaving something like that in the celing...

Is there any other suggestions that anyone can come up with?

 

[topquark]

Burnt out? What did you use as a heatsink?

 

[BillyTheSparks]

Burnt out? What did you use as a heatsink?

Errrmmm?? Nothing....

I just left it on the floor, to do it's merry business. It expanded slightly on the back, then it cracked and stopped working.

I really have no idea with this. I wouldn't have thought it needed a heatsink as surely it would have said it needed it on the paperwork?

 

[topquark]

Data from the spec:

Power at 25°C	50W with heatsink, 5.5W without heatsink
Resistance Tolerance	±5%
Temperature Coefficient	≤1Ω ±250ppm/°C, >1Ω ±150ppm/°C
Operating Temperature	-55°C → +125°C
Thermal Resistance	1.0°C/W
Limiting Element Voltage	1285Vac
Overload Voltage	2500Vac (Max.)
Dielectric Withstand Voltage	3.5KVac
Insulating Resistance	10000MΩ
Length	50 mm
Width	29.4 mm
Height	15 mm

 

[Knobhead]

This is getting silly.

The customer has low energy lighting, 2 X 7W was mentioned. To stop the slight glimmer a loading resistor is suggested which if we go with the first suggestion of 2K2Ώ which will dissipate about 19.5W of waste heat. Near three times the lighting load.

It’s making a mockery of “energy saving”.

Would it be possible to fit a single halogen somewhere in the circuit? At least it would do something useful.

 

[BillyTheSparks]

This is getting silly.

The customer has low energy lighting, 2 X 7W was mentioned. To stop the slight glimmer a loading resistor is suggested which if we go with the first suggestion of 2K2Ώ which will dissipate about 19.5W of waste heat. Near three times the lighting load.

It’s making a mockery of “energy saving”.

Would it be possible to fit a single halogen somewhere in the circuit? At least it would do something useful.

Thank you Tony, that is exactly what I have been thinking.

So talking to another wholesaler we came up with this; wiring a 25a modular contactor/relay in the smallest possible enclosureand placing this in the ceiling void.
Wring the switched live to A1 then link that to the top terminal 1, wiring the light from the bottom terminal 2, then wiring the neutral to A2 then linked to the light fitting.

This will enable the contactor coil to take the 74v constantly without pulling in the contacts, and when the switch is live this will then pull in the coil and the contacts switching the lights on.

Any thoughts on this??

I know putting it in the ceiling void isn't the best idea, but there is no other place to fit it as the house is finished. But it's alot better then sticking a pigmy lamp in the void as mentioned before!!

 

[Knobhead]

It would work and your loading would come down from 33.5W with the resistor to 21W. You could use an octal base relay, they are only 5W.

 

[ronky]

Thanks you brain boxes ,i have been in the trade for 50 years and only the other day came across this induced/ghost voltage for the first time ,thought i was going mad ,you have proved me wrong just seniel i expect ,no sterile, Regards Ronky