MR16 with no transformer?

[Tykey]

Hi all, looking for a little advice please.

Here's the backstory:

I've had an ongoing issue with my kitchen lighting for a couple of months. There are 8 downlighters on a standard (not dimmer) switch, and they are MR16 bulbs. Every so often (a couple of times a week) switching on the lights will trip the downstairs lights MCB. There doesn't seem to be any rhyme or reason for it, or any discernible pattern for when it happens. Most of the time the lights come on as normal, a small percentage it trips the MCB and I have to flick it back on again.

We're having some other work done on the house, and I mentioned this to electrician that's working with us. The first thing he said was if they're MR16's then it's probably a fault with one of the transformers, and he would recommend changing them all over to GU10's anyway, as they can run from the mains without a need for a transformer. That makes sense to me, and he's quoted £200 for it.

However, I pulled out one of the light fittings to have a look, and it seems that the MR16's that are currently in there are running straight from the mains already. Is that possible? I was under the impression that MR16's were 12v, so would always need a transformer.

In fact, there is an old GU10 fitting which has been bypassed, and the fitting is just there to hold the MR16 bulb in place.

I've attached some pictures that hopefully illustrate this.

This is the junction box up in the ceiling:

View media item 102086
The cable running from the junction box, with the MR16 fitting on the end:

View media item 102087
The defunct GU10 fitting:

View media item 102088
My questions is, could the MR16 be running from the mains? If so, could this be the cause of my tripping lights?

Finally, I'm happy to swap out all the fittings and replace with new GU10 ones. This would be as simple as removing the existing MR16 fitting and replacing with a new GU10 one, correct?

Thanks in advance.

 

[Tykey]

Maybe I've done him a disservice...that was what I understood him to be saying though. It's probably me. When I said MR16, I was referring to the two small prongs. Whereas for GU10 I referred to the larger prongs. I now understand that MR16 covers both GU5.3 and GU10 bases.

I believe 240v GU5.3 fittings exist but that is rare

This is probably what he meant, that GU5.3 are usually 12v.

So it's possible that it is still low voltage, but the transformer is elsewhere on the circuit. I thought that each light had its own transformer, which is why I was a little confused.

 

[foxhole]

Could be one transformer, what often happens is people fit transformer to support say 5 x20 watt bulbs (100w) then new owner does not check the bulb size and fits replacement 35 or 50 watt bulbs which overloads the tranny and can cause it to trip.

 

[333rocky333]

All 8 lights are possibly wired back to Two or more Torroidal Transformers, it is common for older ones to have high inrush currents and are prone to trip Type B mcb's.

Ignore the waffle Multi faceted Reflecter MR lamps are becoming scarce now, the lighting industry has adopted the reference
MR 16 for 12 volt and Gu10 for Mains voltage lamps

 

[EFLImpudence]

Ignore the waffle Multi faceted Reflecter MR lamps are becoming scarce now, the lighting industry has adopted the reference
MR 16 for 12 volt and Gu10 for Mains voltage lamps

Sorry Rocky - can't let that go.

If that is the case then it is complete nonsense and the industry must be run by idiots.

 

[ericmark]

If it is fed by a transformer like shown by Rocky then you can fit LED lamps which is likely the cheapest way around the problem. And for it to trip on switch on likely is that type of transformer.

winston1 is correct, you can get G5.3 lamps in a series of voltages, however 12 volt is the most popular and voltage likely written on the bulb. With a low load from LED lamps the transformer is less likely to cause the MCB to trip.

I have swapped all mine with cheap Lidi lamps all clearly marked 50Hz so are AC not DC, you can get DC but they are more expensive and your unlikely to find them in high street shops, same goes for any G5.3 base lamp, yes are made in other voltages but unlikely to find one in a high street shop.

They are normally miss labelled as low voltage, 12 volt is actually extra low voltage in nearly every country but USA, however they are often called low voltage, but be be safe read voltage on the bulb.

 

[ban-all-sheds]

Sorry Rocky - can't let that go.

Not doing so will do no good.

If that is the case then it is complete nonsense and the industry must be run by idiots.

Be that as it may...

 

[ban-all-sheds]

We're having some other work done on the house

I would strongly advise that you extend that work to include replacing the kitchen ceiling and changing the lights to a smaller number of much bigger ones.

 

[JohnW2]

If that is the case then it is complete nonsense and the industry must be run by idiots.

I'm trying to think of an appropriate response to that one

Kind Regards, John