Another one for the Sparks, Lightiong CCT MCB tripping

[MattH]

I've just added 6 new 4ft twin battens fittings to a lighting circuit.
The circuit already had 5 4ft twin fittings.

The fittings have twin 18w LED tubes and starters in them. All fed with 1.5mm T&E from a 6A B type MCB.

So 11 fittings total, with 22 x 18w 4ft tubes totaling 396 Watts, with power factor of 1.8 that's still less than 2A (about 20M total to last fitting).

Problem is that when all fittings are connected after about 5 mins the MCB trips.
If I disconnect any 1 fitting the MCB stays connected.

Any ideas? Even if I take the full load of the ballasts (non HF type) into account then it's still less than 4A with power factor applied.

 

[angellonewolf]

ones got a faulty ballast ? have you got an amp meter clip on type ?

 

[Dee J]

Puzzled... All the details about power factor and starter type suggest fluorescent tubes... But then you say led? If it is led then get a clampmeter on the circuit and see what they really take (shouldnt be power factor issues with leds).

 

[Dee J]

And if they are led tubes then you probably can rewire the fittings to ditch any chokes, starters etc. Most led tubes are entirely self contained with internal power supplies.

 

[MattH]

I have already swapped out a fitting for another new one with no effect. And I have now disconnect a different fitting which solves the problem i.e. If I take one fitting out of circuit then the rest work.

Dee J, the fittings are standard Fluorescent fitting with LED tubes and starters installed. Hence working with power factor etc in mind.

 

[MattH]

ones got a faulty ballast ? have you got an amp meter clip on type ?

I haven't got a clamp meter, but at the end of the day I can install my Fluke inline to measure. I can't see how they could possibly be drawing more than 6amps though unless some very big fibs are being told by the manufactures.

 

[Dee J]

How do you configure a starter with an led tube? Ok some retro-fits leave the choke in place, but for no useful function, and maybe in this circumstance to detriment. The starter unit supplied with many led tubes is just a short circuit bodge to get power to the right place. Most led tubes just need L and N directly connected. Some have L one end and N the other, others have L and N on one end and a shorting link at the other.
Looked into this because I have had a near fire situation where a faulty led unit caused the choke left in circuit to seriously overheat... But the led was still working, just drawing too much current.

 

[MattH]

The LED tubes come with a replacement starter (as far as I'm aware is just a straight connection inside).
Sorry for the confusing terminology but I am just repeating what the packaging says.

Bottom line there is a standard (NON HF) batten fitting with LED tubes in it and "LED Starters" (be them what they are).

Granted I could pull all the chokes and inductors but then the fittings could never be used for standard tubes.

Could the MCB be at fault? Guess I'll have to get a current reading.

 

[MattH]

How do you configure a starter with an led tube? Ok some retro-fits leave the choke in place, but for no useful function, and maybe in this circumstance to detriment. The starter unit supplied with many led tubes is just a short circuit bodge to get power to the right place. Most led tubes just need L and N directly connected. Some have L one end and N the other, others have L and N on one end and a shorting link at the other.
Looked into this because I have had a near fire situation where a faulty led unit caused the choke left in circuit to seriously overheat... But the led was still working, just drawing too much current.

This sounds sensible as the circuit on trips after about 5mins.
I'll get a current reading and update.

 

[MattH]

Right, bit the bullet and grabbed a clamp meter.

So ten fittings with 2 x 18W LED tubes in each is pulling 7.7A!
These are the Ledhut fittings sold for their LED tubes and the instructions clear say that no rewiring of the fitting is required.

So much for the energy savings promised with the LED tubes.

I measured another circuit with ten of these fittings at the other side of the workshop and sure enough 7.8A!

So now I have to go around 21 fittings and pull the gear trays and rewire around the ballasts.

Joy.

 

[MattH]

So I've just confirmed. Each of these fittings is pulling 0.7A without any tubes in it.

 

[Dee J]

So I've just confirmed. Each of these fittings is pulling 0.7A without any tubes in it.

Hmmm. Losses in correction factor caps? Nothing else will be in circuit with the tubes out.

 

[WorkshopChris]

Am following with interest as will soon be looking at a lighting upgrade in the home workshop.

So I've just confirmed. Each of these fittings is pulling 0.7A without any tubes in it.

Was that 0.7 A measure with a clamp or conventional meter.
Hope you find a easy solution.

 

[MattH]

Indeed, two inductors inline with the tubes, so not doing anything and one 10uF cap.

Ridiculous.

 

[MattH]

Am following with interest as will soon be looking at a lighting upgrade in the home workshop.


Was that 0.7 A measure with a clamp or conventional meter.
Hope you find a easy solution.

It was measured with a clamp meter, I had 10 fittings all running, wired out the gear on one and remeasured. Went from 7.7A to 7A.

So the solution is to get on a ladder for all 21 fittings and open them up and use 3 Wago connectors per fitting to bypass the gear.

 

[WorkshopChris]

So this may be a little bit smoke and mirrors to get a sale,

These are the Ledhut fittings sold for their LED tubes and the instructions clear say that no rewiring of the fitting is required.

I can only imagine how mad you must be.

 

[MattH]

your other option for a quick fix (given that its 1.5mm2) would have been to swap the 6 for a 10 (the cable will take the load, well unless you have it buried deep in insulation)

You sure the fittings don't have some form of battery back up in them (albeit not fully connected) ?

That would king of defeat the purpose of LED's though. The cable is all single runs in PVC conduit.
I have spent the morning going around every fitting and bypassing the cap and ballasts.

I will get a reading later but current draw per circuit should of gone from 7.7A to 1.7A.

No battery backup, these are simple cheap fittings sold by LedHut along with their retro fit tubes.
Seems the starter gear is just very low quality and is a lesson not to trust the specs.

I feel for others that have fitted these under the belief that they are saving loads on power consumption without realising that the fittings are drawing a further 132W on top of the 36W for the tubes for no reason.

 

[MattH]

Right, I couldn't resist. I just opened the CU and put a clamp meter on each cct.

Cct 1, 11 fittings was 8.5A, now 1.6A
Cct 2, 10 fittings was 7.7A, now 1.5A

Think I will be leaving a review on these fittings!

 

[MattH]

 

[eSCHEn]

Matt that is utterly pants man. 80% power drop just by wiring them the right way.

Definitely a review needed!