Amptec 12kw boiler melted incoming cables

[gas4you]

I would suggest a mod moves this to Electrics. Although most of us posting on here know basic electrics for heating systems, when it comes to something as serious as this, with this amount of current being used, you need expert advice from a sparks, not a heating engineer or plumber

 

[DP]

10mm cable terminated onto a PCB is madness. What if the PCB track cannot conduct the high current- it will overheat and kill the connector.

Have in the past seen boilers wires with 2.5 T&E. This cable often just pulls the connector off the PCB. Hate to think what 10mm or even 16 would do.

How about taking voltage readings. Bad connection or even resistive connection might show drop in mains voltage.

 

[Agile]

It would be unusual to be seriously wrong but anyone coming across that overheating would have measured the current with a clamp on meter.

Sometimes the mains voltage is rather high and as the power is I²R that can cause a significantly greater power input.

Not many electricians are very comfortable with electric boilers!

Tony

 

[trey]

My 12kW (max) electric boiler pulls 45A when configured as "10kW", so in 12kW mode I would expect 54A.

Unlike the Amptec my boiler scales the power, so I've never seen it pull 45A for more than 30 mins and in this time the 16mm2 cable never gets warm.

 

[mattylad]

Can you post a picture of this terminal block etc?

 

[ricicle]

Sometimes the mains voltage is rather high and as the power is I²R that can cause a significantly greater power input.

Not many electricians are very comfortable with electric boilers!

Tony

A 12Kw boiler rated at 230V would become a 13Kw boiler at 240V so you would hope that this would be allowed for in the design if there was a chance that the current could be higher.
Any joint on a cable, particularly carrying currents like that, has to be electrically and mechanically sound. This would mean checking the connectors are rated for the current and 'man' enough to accomodate the cables. Is the cable/connection in the boiler anywhere near hotter than ambient conditions thus causing overheating?

 

[mrrigidtool]

pulled the connector off the two little prongs soldered onto the board have blown as well and desoldered them selves, the actual point at which there soldered onto the board are about the size of a toothpick not impressed with build quality. sparky says his job is to run a cable in 10mm with a 30ma break rcd with 240v as disribed in the hand book. he has metered the cable and is happy that its in accordance with the manual. Aptec engineer does not know whats wrong as he needs to swap board to power it up to check it and is not qualified to comment on wiring however cant see any fualt with it. aptec wont admit fault so engineer cant get the spare to fire it up and at least check it over. My expert advice, dont buy this piece of ****e as the connector terminals in my watch are bigger, and the fact that they diagnosed the fualt over the phone origanly and concluded i was putting in the wrong electric is a joke. Any idea who deems these safe and who i can complain to.

 

[Spark123]

i did thats the problem, the electrician says the fuse box is sound and in the manual is says 10mm connected via a 30ma rcd does not specify amps.

Any spark should be able to work out the necessary MCB size for this tho.
I take it that the cable is connected back in via the MCB?
12kw@240v is bang on 50A.
If a connection has not been quite tight enough then the heat generated will not do the PCB any favours and more than likely have led to the device unsoldering itself like you have found.

 

[mrrigidtool]

sparky worked it out as 50a and fitted a 50a mcb it would trip every hour so he wired it straight into the 80a rcd, the hand book asks that its wired into a rcd 30ma break but does not specify size. ordered new board and will refit using new 10mm is it ok to leave it wired into 80a rcd as the 50a mcb will not do the job

 

[plugwash]

sparky worked it out as 50a and fitted a 50a mcb it would trip every hour so he wired it straight into the 80a rcd

It is far from ok to wire direct into the incomer with no overcurrent protection. If a breaker is tripping regularlly it either means the calculations were wrong or the equipment is faulty. Either way it needs to be investigated and sorted.

 

[Spark123]

sparky worked it out as 50a and fitted a 50a mcb it would trip every hour so he wired it straight into the 80a rcd, the hand book asks that its wired into a rcd 30ma break but does not specify size. ordered new board and will refit using new 10mm is it ok to leave it wired into 80a rcd as the 50a mcb will not do the job

Does he have a good lawyer?. The hand book may specify an RCD, the 80A bit is the maximum it can safely handle. It does not trip if this rating is exceeded. He should know that.
A pluggy says - tripping is an indication of a problem. A 50A MCB doesn't trip at exactly 50A, iirc will take about 56A indefinately. What he has done is connect it directly to the DNO fuse. This may not provide adequate protection against overload / fault current so could be a fire risk.

 

[mrrigidtool]

how would you wire it in if it was yours. would you keep the rcd and add a 60a mcb

thanks

 

[plugwash]

Not without further investigation first.

IMO this would mean at least the following

Use a clamp meter to check how much it was actually drawing.
Measure the mains voltage
Read the manufacturers specs carefully, find out if the rating is 12KW at 230V or 12KW at 240V. Find out if the mains voltage you are measuring is within the manufacturers specs.
Based on the manufacturers ratings and taking account of any difference in voltage between the voltage the power rating is at and the mains voltage calculate how much current it should be drawing. Compare this with what it actually drew.

 

[mrrigidtool]

will do however to test it means to wire it in and need to size up mcb first. Will run it off 60a and test it on full power.

 

[mrrigidtool]

just found on there new site 12kw@240 11kw@230v 50a rating they recommend 63a mcb they could have put this in the hand book reckon they have had problems before now there including the advice on the new spec sheet.