Ground floor lighting trips out mcb

[Biggy]

Hi everyone,

My first post but straight in with a couple of issues.

I'll start with a 6amp MCB that keeps tripping out relating to ground floor lights.
For your info:

There is 10 x 3w led recessed lights in Kitchen, 8 x 3w led recessed lights ,plus a main central Led light (approx 100watt equivalent ) in the room next to the kitchen and then the same amount of lights and Main central light in the Back room. I would say the combined wattage including two outside lights (40watt each) will be around 480w so let's call it 500watt on the ground floor.

From my understanding a 60w bulb draws around 0.5amp so in effect 30 of the 60w bulbs (around 1800watt combined ) would require a 15amp breaker which would be comfortable, so based on this theory is the 6amp MCB actually overload on 500watts on Ground floor and this tripping the breaker .

The breaker does not trip immediately as can take 5-10mins sometimes longer, and in some instances it has tripped even when ground floor lights have been OFF.

The joist spaces have all been insulated with rockwool if this makes any difference as I want to eliminate any possibility before I start questioning my electrician who advises that maybe I should fit a 15amp breaker in as he feels 6amp is less power for 30 odd lights .

Can anyone shed LIGHT on this

I'll come to the second issue after I can get a solution to this.

Sorry for the lengthy explanation but I know there's nothing more frustrating than not arming knowledgeable people will full info and expecting solutions. Hope I've not missed anything out.

Hope to get a few responses and guidance as I have basic understanding of electrics.

Thanks

 

[DC-backfrom the past]

as said previously ,,,why would you want to protect with a 16amp mcb.
because its tripping ? if only it was that simple .
this could be a loose connection, it could be a bulb thats faulty, it old be a faulty switch.
too many things , it could be damaged insulation that only causes a problem under certain circumstances.
I suggest you get continuity checked and insulation resistance test.
if that doesn't find the fault take note of the conditions when the fault occurs.
also has there been any recent work done in the house that could affect the wiring ?

 

[Markyd]

Get the sparky who tested it back and tell him to do it properly this time.....

 

[Midwest]

Just another thought; seems a fair bit of led lighting on one circuit, wonder what make & how they are switched?

 

[Biggy]

Thanks a fair few replies overnight, so I'll try answer as best I can.

The rewiring has been brand new throughout the house

The certificate shows a tick box next to "insulation resistance between live conductors" and also to "earth".
Schedule of items tested list has all been ticked .
Single phase prospective fault current is written as 0.99ka.

The led lights are 3w+3w recessed with a transformer with each light.

No bulbs are blown on ground floor (one transformer blown upstairs but that's not on the same circuit )

I have not checked the outside light just yet and it was screwed in a little loose but at the moment I don't have a bulb in it so I will put one in and then check again to see if they are on the same circuit too as maybe I can eliminate water ingress from outside light.

Is there any basic checks I can do myself which could be the reason .
As for the fuse that's tripping on CU, I have the BG 10way unit from screwfix with RCD switches too. The one that's tripping is the 6amp marked ground floor lights .

I will try get a picture up as soon as I figure out how to.

Any suggestions based on info I have now provided.
Thanks

 

[Biggy]

Here is the CU I have and the 5th switch from the left keeps tripping which is my ground lights marked there.

 

[telectrix]

always the possibility of a rogue MCB. is there another 6A on the same RCD?

 

[Biggy]

I don't know if there is a spare I'll check and see if one can be swapped over just to test it. Should I turn all the CU off and do I just pull the breaker out and click back in to test with a different one ?

 

[telectrix]

no. you turn off main switch, then move the circuit wires to a different MCB. if it's on the other RCD, you need to move the N to the appropriate N bar.

a better idea would be to clamp the L coming out the MCB and see what current is flowing. for this you'd need a clamp meter.

 

[DPG]

I don't know if there is a spare I'll check and see if one can be swapped over just to test it. Should I turn all the CU off and do I just pull the breaker out and click back in to test with a different one ?

I would get a sparky in as soon as you can.

 

[Toneyz]

I think that as long as you have not got a fault to earth and the RCDis not faulty one of the drivers could be faulty due to the reason I gave in post 15 or heat damage causing a L-N at a lampholder. What has thrown me is that you say it sometimes trips when the lights are all off or do you mean when you turn them off. Just to change the MCB to a 16A one is not going to find the problem and could make the installation dangerouse or non compliant with the regs.

 

[Toneyz]

no. you turn off main switch, then move the circuit wires to a different MCB. if it's on the other RCD, you need to move the N to the appropriate N bar.

a better idea would be to clamp the L coming out the MCB and see what current is flowing. for this you'd need a clamp meter.

This would at least tell you your F.L.C. and then do a installation restance test this will rule out a earth fault.

 

[Biggy]

OK, I thought I could have picked up a new 6amp breaker and just replaced it in same place but guess not then . Sparky that wired all house now not answering his phone. He's had his money and now he probably not interested so will give him benefit of doubt and wait couple days more otherwise I will get building control to chase him up and let them know the wiring needs independent testing through them as I feel it is unsafe for me and my 5 young children. Maybe that will give him a jolt to get up and make it all safe as should have been.

 

[DPG]

Keep trying him. Annoy him till he responds.

 

[Toneyz]

Do any of the outside lights altough I think you said has no lamps in have sensors on them?

 

[Biggy]

Outside lights don't have sensors. Am in toolstation now and with pick up outside bulbs and check them and report back later tonight.