Patio Heaters Tripping !!!

[Jamesy]

Hi I have a small problem with a job for a friend which i said i would sort out for him, He owns a Resturant/Club with an outdoor smoking area...

There is two patio heaters on one circuit (2.5mm cable) protected by a 32a MCB. After approximately thirty minutes the 32a MCB will trip in the CU.

As the heaters are 2kw each they should be well within tripping times for a breaker this size.

Would I be right in considering a TYPE "C" Mcb as there could be an inrush from the fluorescent fittings of these heaters?

Thanks People!

 

[telectrix]

is the circuit a radial or RFC? if the former, the 32A MCB is oversized. should be no more than 20A. have you tried clamping the cable to see what the heaters draw?

 

[Jamesy]

Hi Telectrix aww I know there is two other patio heaters on there own circuit which are run on 20a mcb's but as this is the only circuit which has two loads on the one circuit i am assuming the previous spark decided to up the breaker thinking this would solve the tripping problem but obviously hasn't- as they are on a radial!

So I would of used a 20a personally aswell but i havent invested in a clamp meter yet haha i know this is what i was thinking!

I was also thinking it wouldn't hurt to seperate the two heaters on to there own circuit with their own 20a MCB's respectively. its a bit more money for 5 meteres of cable but whats 5 metres between friends :S

 

[Marvo]

You need to establish what the load is before you plan any remedial work. Borrow a clamp meter. I would also run the heaters for a while and do an IR test on the whole circuit while they're hot. Finally I'd check the entire circuit and make sure there's nothing that's been spurred of it as a sneaky.

 

[Octopus]

What happens if they only use 1 heater?

 

[malcolmsanford]

4kw is approx 18 amps so the breaker should be fine unless the "upped" breaker was already a 2nd hand one and therefore could have been on it's last legs.

As the lads say IR and amp testing the circuit is a must just to start with and you need to get/borrow some meters.

Another thought is there a pattern to it ie rain ?

 

[ian.settle1]

2kw = Approx 9A 2 x 2kw=18A

Sounds like you have an earth fault, as after the 30-mins the insulation is breaking down due to the heat.

 

[sedgy34]

So the 32a mcb isn't protecting the 2.5 mm cable is it, first thing change mcb then look at the problem, are both heaters on the 1 radial circuit is that why it's tripping on overload.

 

[Deleted member 9648]

Hi Telectrix aww I know there is two other patio heaters on there own circuit which are run on 20a mcb's but as this is the only circuit which has two loads on the one circuit i am assuming the previous spark decided to up the breaker thinking this would solve the tripping problem but obviously hasn't- as they are on a radial!

So I would of used a 20a personally aswell but i havent invested in a clamp meter yet haha i know this is what i was thinking!

I was also thinking it wouldn't hurt to seperate the two heaters on to there own circuit with their own 20a MCB's respectively. its a bit more money for 5 meteres of cable but whats 5 metres between friends :S

If he did he wasnt a spark.......5 day wonder possibly.

 

[robsparky1975]

^^^^^^^^^^^^^agreed,there are electricians and there are "electricians".take your pick^^^^^

 

[Jamesy]

2kw = Approx 9A 2 x 2kw=18A

Sounds like you have an earth fault, as after the 30-mins the insulation is breaking down due to the heat.

Possibly! even so i have to change the cable anyway for this reason to have them on seperate "New MCB's" cheers for the response in here

 

[Octopus]

Possibly! even so i have to change the cable anyway for this reason to have them on seperate "New MCB's" cheers for the response in here

Dare I ask what tests you have done???

 

[Jamesy]

I havent done any yet apart from being there and watching it trip.

 

[Octopus]

I havent done any yet apart from being there and watching it trip.

Me thinks its time to do some proper tests and fault finding.

 

[telectrix]

methinks if the heaters are tripping, stop the customers smoking weed in the smoking area.