Amptec 12kw boiler melted incoming cables

[RF Lighting]

An undersized cable is NOT their responsibility.

YOU have to design the installation to be suitable for the environment where it is installed.

YOU have to size your cable in accordance with BS7671 to ensure a safe and reliable circuit.

If you carry on installing this undersized cable, and bypassing MCBs to stop them tripping et al, you might as well save your self a load of time and effort and just set fire to your house right now.

 

[mrrigidtool]

DON'T tin the wires FFS

You've already had a failed mains connection. Tinning the ends will nicely provide you with another failed set of connections.

I really think you need to be employing the services of a commercial electrician.

Your joke of an electrician didn't have the first clue what he was doing, and I'm afraid it sounds like you don't either.

not a bad suggestion regarding a commercial spark, however the point is unless its done exactly as in the hand book then they will always pass the buck if it goes wrong, and now they have provided me with a diagram then theres no actual theory or maths left in the eqation other then to follow the diagram.

 

[Spark123]

Does the handbook refer to BS7671?
Does it specify the mains cable size and how it is to be installed?

 

[mrrigidtool]

An undersized cable is NOT their responsibility.

YOU have to design the installation to be suitable for the environment where it is installed.

YOU have to size your cable in accordance with BS7671 to ensure a safe and reliable circuit.

If you carry on installing this undersized cable, and bypassing MCBs to stop them tripping et al, you might as well save your self a load of time and effort and just set fire to your house right now.

sorry you mentioned under sized cable, there hand book states that the terminals are sized upto 10mm, we used 16mm so there was no undersizing.

 

[Spark123]

It doesn't really matter what about what the terminals are sized for - it is what the cable as installed is rated at which is more important.
If the cable is too big to fit into the appliance then it may be connected in using a short length of smaller diameter cable joined to the larger cable local to the appliance.
All the cables need to be sized on an individual basis for each installation, no two installations are identical. This includes assessing any factors which can de-rate the cables current carrying capacity. If the cable is any distance or passes through any thermal insulation then it will may not be suitable for carrying the current.
The standard used by most electricians in this country is BS7671, the current version being the 17th edition.

 

[ban-all-sheds]

Not really - the cable needs to be 63A as installed yes, however there is no reason you cannot change size depending on the environment where the cable is installed for example from CU to local 63A switch in say a 35mm and from the 63A switch to point of utilisation in say a 10mm high temp rubber.

True - as long as the cable from the switch to the appliance will carry 63A without going above the temperature limit for the switch...

 

[Agile]

There are a lot of people making vague and theoretical postings with no reference to this particular application!

The plain facts are that the current drawn is not expected to exceed 60 A.

The terminals on the appliance are sized for 10 mm² cable.

There is no evidence to suggest that 10 mm² cable is not adequate!

Yet using this size as recommended by the manufacturer has resulted in the PCB connection overheating.

Now whilst I am concerned that no-one seems to have measured the mains voltage, all the expectations are that the unit was fitted with the correctly sized cable and has still failed and the manufacturer is acting in a very odd and unhelpful maner.

If it helps, I would offer to present your case free of charge in our local area if you took it to court.

Tony

 

[Spark123]

There is no evidence to suggest that 10 mm² cable is not adequate!

Quite the opposite infact - there needs to be evidence to prove that it is.

Yet using this zize as recommended by the manufacturer has resulted in the PCB connection overheating.

Manufacturing defect, loose/bad connection, or was it 16mm?

Now whilst I am concerned that no-one seems to have measured the mains voltage

Part of working to BS7671, as most electricians do.

If it helps, I would offer to present your case free of charge in our local area if you took it to court.

Tony

Don't forget to take the EIC with you

 

[IloveDIYNot]

Hi mrrigidtool,

I too have all the qualifications in electronics but when it comes to something like this , get the big boys in if your not sure. Instead of being chocked on fumes you may be running for your life.

But with that said, check out TLC's web site for cable size calculations http://www.tlc-direct.co.uk/Book/4.3.9.htm , this may help you.

Regarding connection, the manual shows how to connect the system.

"Your cable" size to the isolator near the boiler which is required and then a 10mm feed to the boiler connector as others have suggested. I could not find a high temperature cable at 10mm though , so you may wish to use heat shrink sleave at the connection point. Please do not solder the tip of the wire too, this will reduce on the contact area in the connection block.

I have to say to however, I was surprised to see the MCB at the far end of the consumer unit, logic would say that the high current drawers would be near the isolator.

 

[mrrigidtool]

hi thanks for all the advice went down to the local lecy suppiers i use he is a electrician as well worked out that the cu prevous spark put in was fine with 16mm armoured, Obviously thats were it ended with him, so supplied me with 60a mcb and 100a dp switch and box to mount directly above boiler even as the cu is only a foot away he said lets follow amptecs scheme. Supplied me with 10mm heat resistent cable, wired it all in works fine.

However main fuse started to cook when tumblre dryer was on then blew EDF changed it and its only 65a they said that the head will not support 100a. can anyone recomend a switching device that will cut the boiler circuit when oven or dryer circuit is used.

 

[ban-all-sheds]

hi thanks for all the advice went down to the local lecy suppiers i use he is a electrician as well worked out that the cu prevous spark put in was fine with 16mm armoured,

Armoured?

However main fuse started to cook when tumblre dryer was on then blew EDF changed it and its only 65a they said that the head will not support 100a.

What did the original electrician put on the EIC for the rating of the supply fuse and the maximum demand of the installation?

can anyone recomend a switching device that will cut the boiler circuit when oven or dryer circuit is used.

//www.diynot.com/forums/viewtopic.php?p=1069311#1069311
.
.
.

 

[mrrigidtool]

still waiting for a ticket from him, basicly his not coming back, supply head was not labelled when i asked him at the time he told me it was 100a, there was a hemley block already on the wall so he tailed in a 100a dp isolator and run the 16mm armoured into it which then ran 10m along the wall to the nes cu next to boiler. Now fitted as instructed 60 mcb and also neutral rcd prtected into a 100a dp switch above boile then into boiler using heat resistant 10mm cable cable length 30cm to switch 30 cm to boiler. I also have electric oven, tumble dryer, washing machine and a 6kw direct megaflow. The mains cable coming in apparantly wont support 100a supply fuse, i did quistion this with him at the time assurred me should be ok as it only that size above ground below is alot thicker. Need to switch between them for safety's sake the boiler has a 3a input for control on it that switches it o and off. Is there a priority switching unit any one can recommend. I never got into this mess on my own accorred trying to be clever i employed a sparky who is a distant family member did not ask for a discount just wanted it done. If i had done it my self from the beging i would have researched it first and simply would have stopped when i came across the 65a supply fuse.

 

[electronicsuk]

You quite simply need to bring down your maximum demand (for example, get a gas boiler) or have a larger supply installed.

 

[jason1958]

Can you PLEASE post a picture of the terminals?

1 - A view from above over the terminals
2 - A view into the terminals


There are MANY kinds of terminals.

Tunnel cage-type...
- Conductor must be crushed into oblong shape
- eg, CU Isolator, requires 2-step tightening or work loose, heat

Tunnel round-type...
- Conductor more easily deforms (less of the 2-step tightening problem
- Less of the 2-step tightening problem

Screw-over-plate/washer-type...
- Conductor must be bent around under plate to balance force & maximise contact area

Screw-over-washer-type...
- Some are better suited to ring-crimp terminal


NOTE
- Do **NOT** run the boiler without an overcurrent device (MCB, Fuse)
- You **REALLY** need to let people see the terminals

Certain termains require specific termination to minimise heating.

H07RNF is Fine strand whereas FTE is 7-strand.
That means contact surface area can be higher, lower contact heating.

HOWEVER the terminal design *matters* re how you terminate.
Otherwise the terminal will simply desolder off the PCB - everytime.


Without an overcurrent device...
- You are relying on the Main Fuse, BS1361 BS88 60-100A
- Such fuses take 800-1000A to blow instantly (huge bang)
- Such fuses will handle a small overload for a LONG time
- In which time your house has burnt down

There could well be a problem with the heater.

Go buy a digital camera from a supermarket and sell it on Ebay when done, cost spread £10-15.

 

[mrrigidtool]

hi thanks for your reply just posted pics of terminals as i was waiting forr new board to arrive the old one has had a treble by-pass operation to get it going will swapp them over this week. the terminals when screwed the back contact is pulled towards the front and the contacts are grooved.
The boiler is runnuing on a 60a mcb and nuatral is rcd protected as well.

//www.diynot.com/network/mrrigidtool/albums/