Tripping issue....ideas needed!

Leesparkykent · Feb 25, 2016

Looking for ideas... completed a job recently of 11 new build houses and above the open staircase we have installed a rope light made by Tamlite similar to the one in the pic. This light is two way as above the stairs. On 3 of the property's every now and again the MCB for this circuit trips when either of the two way is switched (note this doesn't happen all the time, probably once in every 25). I'm sure most of the regulars on here will know I've conducted the relevant tests such as insulation resistance etc and comes back >299 on all including the two way in all positions. The transformer is mounted in a stud wall with no insulation and a little access trap. What do you think the problem could be....my thinking now is a dodgy batch of transformers but was wondering if anyone else has ever experienced similar problems? Ps It all comes part of a kit with 5 x mr16 lamps.

[ElectriciansForums.net] Tripping issue....ideas needed!

telectrix · Feb 25, 2016

i'd suspect inrush. fit a C type MCB as long as Zs is compliant. alternatively, buy one of these:

davesparks · Feb 25, 2016

Is it a proper (wire wound) transformer or an electronic one?
I've had the exact same problem with a bunch of external firings which used proper transformers, I think it ended up on a 10A D type to cope with the inrush.

I know a lot of those things have a toroidal transformer in a decorative box. If possible try an electronic transformer (I'm pretty sure aurora make a 250VA one)

Leesparkykent · Feb 25, 2016

Haha,I did think that but its only 5 mr16's. I'll clamp it tomorrow and see,only flew in there quickly on way home tonight.

Pete999 · Feb 25, 2016

Leesparkykent said:
Looking for ideas... completed a job recently of 11 new build houses and above the open staircase we have installed a rope light made by Tamlite similar to the one in the pic. This light is two way as above the stairs. On 3 of the property's every now and again the MCB for this circuit trips when either of the two way is switched (note this doesn't happen all the time, probably once in every 25). I'm sure most of the regulars on here will know I've conducted the relevant tests such as insulation resistance etc and comes back >299 on all including the two way in all positions. The transformer is mounted in a stud wall with no insulation and a little access trap. What do you think the problem could be....my thinking now is a dodgy batch of transformers but was wondering if anyone else has ever experienced similar problems? Ps It all comes part of a kit with 5 x mr16 lamps.

Inrush current when the lights are switched on, seen it before.

Leesparkykent · Feb 25, 2016

davesparks said:
Is it a proper (wire wound) transformer or an electronic one?
I've had the exact same problem with a bunch of external firings which used proper transformers, I think it ended up on a 10A D type to cope with the inrush.

I know a lot of those things have a toroidal transformer in a decorative box. If possible try an electronic transformer (I'm pretty sure aurora make a 250VA one)

Yeah its definitely a wire wound transformer.

davesparks · Feb 25, 2016

Leesparkykent said:
Yeah its definitely a wire wound transformer.

Inrush then, either a C type or bigger B type of possible or else try the electronic transformer

Lucien Nunes · Feb 25, 2016

I fitted yards and yards of something similar in our old offices and had all sorts of headaches with inrush. I ended up changing some of the transformers to better ones. A couple of them might have got converted to electronic, but proper 12V DC PSUs not electronic lighting transformers with HF output, as the cables would have been well over the permitted max length and might have radiated hellish interference.

Richard · Feb 25, 2016

I'v had this problem before. If it is a wire round TX then I'd agree the initial inrush of energising an inductive load is highly likely your issue. Your only hope I feel will be to use Type C or D MCB's. Hopefully you've a good Zs!!

Regards

davesparks · Feb 25, 2016

Of course you could just wait a few months until the lampholders have burned out along with the connections to the wire rope, then it'll not work anyways and so it won't trip

Leesparkykent · Feb 25, 2016

Richard said:
I'v had this problem before. If it is a wire round TX then I'd agree the initial inrush of energising an inductive load is highly likely your issue. Your only hope I feel will be to use Type C or D MCB's. Hopefully you've a good Zs!!

Regards

The houses are tiny and bang next to the substation so shouldn't be an issue lol

Leesparkykent · Feb 25, 2016

davesparks said:
Of course you could just wait a few months until the lampholders have burned out along with the connections to the wire rope, then it'll not work anyways and so it won't trip

Agreed lol the fittings are carp but that's what the customer wanted.

mattg4321 · Feb 25, 2016

Again, definitely inrush current. Had this before more than once over the years with those.

They were a bit of a fad about 10 years ago, haven't fitted any in ages!