Shop lights keep tripping

[Spark123]

You are the installer!

JohnHammer. It's at this point you wish you hadn't been been such a skinflint and employed a pro.

Or sought in-formed and experienced advice BEFORE starting on the DIY project.

I assume that as the public use these rooms that in the event of the lights going out there is an alternative source of secure lighting to enable save exit from the room.

Even still, work on commercial premises falls under the umbrella of the Electricity at Work Regulations. Part of these regs calls for "Persons to be competent to prevent danger and injury". The fact the OP doesn't know about MCB types nor Kw sets all sorts of alarm bells ringing, is his work to BS7671? Is there an EIC? How could he even start to invoke the defence regulation? To me it doesn't sound like it wants a quick fix, it wants a qualified electrician to comment on the whole installation. Commercial environments are not areas for the DIYer to practice.

 

[dingbat]

Even still, work on commercial premises falls under the umbrella of the Electricity at Work Regulations.

So does domestic. If you are working on dwellings and you end up in court it's EAWR they'll use to hang you, for certain.

 

[JohnHamer1977]

I'm competant enough to do a simple elec install... I have a ONC in electrical and electro mechanical engineering whch have basic electrical installation covered.

United Utilities engineer came out to have a look iwth the 3 phase inspection... he advised us to "suck it and see" with the single phase supply as it is with tolerances but borderline.

All wiring is to IEE regs - I had a C&G qualified spark on site at the time.
No more negative digs please, if you can not help DON'T COMMENT.




Now to the serious people who are trying to help me...
I changed the breaker today. Spoke to an installer an he agree'd with the possiblity of it being a thermal conduction problem.
So removed the tempramental breaker all together and changed the position in the consumer unit.

CEF tech suggested a motor surge protection type breaker... he thinks the sunbeds turning on and the quick surge created could make the other breakers trip, even if they are not on the same circuit... along with the heat would exagerate the problem.
They suggested if the prob carries on to try a Type D breaker???
What do you think?

 

[Spark123]

What is the Zs on the EIC for the circuits you wish to change for type D breakers. Why would you want to change them if they are not a problem? What is the size of supply? What is the loading? Why have you removed the breaker and what have you connected the circuit to? Can you scan and post the schedule of test results for the installation, will help to give a better overview?

 

[JohnHamer1977]

As said, a technician at an elelectrical suppliers suggested the type D... hence me asking on here what people thought.

I wouldn't want to change them if they were not the problem, I thought that was obvious by the fact I put "suggested if the prob carries on to try a Type D breaker"

The breaker was removed for the reasons stated in previous posts, read the thread again for clarity.

 

[Spark123]

So you removed the breaker and did what? Connected it to another circuit? Replaced the breaker? Type D breakers are not usally required for lighting circuits.
Still need to know:
What is the Zs on the EIC for the circuits you wish to change for type D breakers. What is the size of supply? What is the loading? What CPD have you connected the lighting circuit to? Can you scan and post the schedule of test results for the installation, will help to give a better overview?

 

[ELZ4742]

type d breakers are motor rated breakers right? 10-20 times nominal rating? i dont think these are a suitable breaker for lighting my ole mate.

 

[JohnHamer1977]

Yeah the CEF guy said they were for motors really but he was thinking onto of the heat it was surge from the sunbeds coming on and off that was being picked up somehow and triping the 6 amp jobby.

At the point where the CEF guy suggested that, a customer who was in the store at the same time suggested the lighting as I described could take a 10 amp... so that was his suggestion.

People have previously said on this thread though that, up rating the breaker to a higher ampage is not a good idea so obviously now am a bit confused.

I'm hoping swaping the breaker for the new one will fix it but nothing wrong with planing my next move if it doesn't. Re-checking all the connections again will have to be the first on although I am confident they are fine.

So to be clear on this... can anyone confirm or deny some of the details for me specifically these points:
1. The old breaker could have been "picking up" on a surge from other circuits?
2. Why is upgrading to a 10 amp a bad thing (I know I shouldn't have to though)?
3. Heat in the consumer box from other circuits can cause lower amp breakers nearby to trip.

 

[Spark123]

Before you can upgrade a breaker it must be determined the circuit can handle the upgraded current and that it can disconnect quickly enough. What is the Zs of the circuit that you are wanting to upgrade? What size & type of cable? What is the installation method? You'll should find this info on the Electrical Installation Certificate. What else is in the CU? What is the supply size?

 

[RF Lighting]

Type 'D' MCBs are not motor rated. They are designed for use with welding sets, X-ray machines, LINACs etc. They are certainly not designed for use with a lighting circuit, and the Zs limit is much lower than a type 'B'.



You shouldn't be taking advice from the bloke in CEF. He is not a qualified electrician, and hasn't seen / tested your installation.

Will he stand up in court and testify that he advised you to fit this unsuitable MCB which caused the shop to burn down?

 

[JohnHamer1977]

I don't have a Electrical Installation Certificate - I ran the wires... my mate (the electrician) installed the consumer unit and terminated connections there.

I don't know the impedance, how important is this?

The cable is I think 1.5 twin and earth.

The lights are daisy chained, feed came from original light fitting feed.

In the consumer unit you have in total top of my head:
32 amp
62 amp (sunbed)
62 amp (sunbed)
6 amp (front room - 9 halogens)
6 amp (back room - 10 halogens)

Supply size is 100A

 

[dingbat]

Like I said, I'd be very concerned about my insurance at this stage. Tightwad.

 

[JohnD]

You mentioned surge from sunbeds.

But I get the impression that you have a slow trip due to heating up.

The heat would not be caused by a switch-on surge.

"D" type MCBs have no additional resistance to heat, only to switch-on surge.

If the MCB was heating up due to overload, an adjacent hot MCB would prevent it losing excess heat, so it would get hotter until it tripped.

Have you tried taking out some of the lamps on the circuit that keeps tripping to reduce the load? Or fitting energy-saving lamps to save yourself money on electricity?

We had early suggestions (and a 14p wager) that the cause was damaged wiring. Can you rule this out yet? Visual inspection and an insulation test would help.

 

[JohnHamer1977]

Like I said, I'd be very concerned about my insurance at this stage. Tightwad.

OK cheers - no need to repeat now mate, your jibes are getting annoying.

 

[JohnHamer1977]

You mentioned surge from sunbeds.
Yes, for a fraction of a second as they start the draw more current

But I get the impression that you have a slow trip due to heating up.
Yes, I personally think it's due to heat conduction.
Don't forget, the 6 amp lights does not trip when the sunbeds are not busy... so it isn't heating up due to itself, or it would trip whenever - it only trips when the sunbeds are busy

The heat would not be caused by a switch-on surge.
No, but maybe the heat would compound a problem if the 6amp was picking up on another switch on surge OR the heat or vise versa I don't know - I am here to ask


"D" type MCBs have no additional resistance to heat, only to switch-on surge.
Yes, I thought the same... same for type C but people have suggested both - would make sense if somehow the 6a was picking up some sort of surge from another circuit... like the sunbeds one - this is what I am asking... can this happen

If the MCB was heating up due to overload, an adjacent hot MCB would prevent it losing excess heat, so it would get hotter until it tripped.
No, I am thinking the adjacent MCB being hot and conduction heat to the next one along... being only 6 amp, causeing a thermal trip - again this makes sense but I don't know if this can happen

Have you tried taking out some of the lamps on the circuit that keeps tripping to reduce the load? Or fitting energy-saving lamps to save yourself money on electricity?
No, can you get energy saving halogens? Also, the load per breaker is not that high, in fact previously BOTH rooms were on only a single MCB (the one that trips). Then I split the rooms to have there own breakers and the one that trips was still tripping (as said, I took this breaker out today and put in another 6amp one, if it was a tempramental breaker it could be solved - just investigaing my options now so I know what to do for the best if it trips again, as it's intermittant it could take weeks before I see the prob again)

We had early suggestions (and a 14p wager) that the cause was damaged wiring. Can you rule this out yet? Visual inspection and an insulation test would help.
Not entirley, I did look at them all when I took all the bulbs out but I didn't nip up all connections which I could do next... I also need to have a look at the switch

thanks