You can still purchase the Proteus 640/2 40A Type 2 M4 from new and there was also a 45A version.
Shower trips the fuse on the consumer unit
- Thread starter Llarius
- Start date
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It is just the 40A device tripping out causing power loss to the shower.
I think there was certainly an element of keeping the costs down. We didn't contract the electrician. He was brought in by the plumbers, and the discussions we'd had with them, was effectively to keep costs down, but above all else ensure everything is safe - even if it pushes our budget up (they understood this as they then suggested to remove the wiring from truking that had been wired on the wall up past a door frame since the room it was in will one day be a nursery/child's bedroom. Hence the cabling was put under the floorboards/chased into walls where necessary.
If that is the case then the rating needs the be suitable for the load, but the cable size has to also be suitable for the fuse rating. That is why it is important to know cable sizing and the route and method that the cable is installed.
Is the installer still contactable, you should have had certificates and a building control notification, as a new circuit was installed for the upgrade.
And exactly where was the cable chased and routed? As you cannot just install cable anywhere when buried in walls, there are permitted safe zones that must be used, if cable is buried less than 50mm and not mechanically protected!
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We weren't given anything. I know this sounds silly, but I'm confident the right cable is in place - I'll check it later when I'm home. Do I just need to measure the width of the grey plastic coating?
And like I said earlier, I didn't have any contact with the electrician. He was arranged by the plumbers.
When you don't get certificates, generally something stinks!
Please read edit!
Please read edit!
I don't know how it was chased etc, but it goes from the consumer unit up through the ceiling, under the floor boards in our box room, then the hallway, and then chased in the wall in the bathroom (I'm sure that's what we were told), to the loft, to then come back down again to the shower unit.
Thanks for that link. I've just had a read of that and the one for through floors, and from what I remember at the time, everything is in order in terms of location/routes. They were very conscientious, and made us aware of bad botches by the previous owners of the house that could cause issues or be to do with safety - perhaps apart from the MCB.
I've just been looking at a few other places online, and can also see the same thing popping up elsewhere with similarly rated shower units and electricians saying 40A is fine where the spec has been for 45A, but to upgrade it if the 40A trips. Perhaps that is what is happening here?
The manufacturers instruction quiet clearly state a 45A device should be used, as trained engineers we are instructed to follow the manufacturers instructions and the 40A device should not have been used.
Although it maybe the case that some appliances can run for a period of time, without an overload being induced, it is bad practise to under rate a circuit.
Although it maybe the case that some appliances can run for a period of time, without an overload being induced, it is bad practise to under rate a circuit.
Assuming it is that simple, and all we need to do is change the 40A device to a 45A one, can you explain to me in plain English what is happening to the shower? I don't understand why it would run at all, or why it decides to randomly fail, or what causes it to fail. I appreciate that this is probably pretty basic stuff, but I just want to understand (on the basis of that assumption) a) what is happening, and b) why, in real English, not engineers speak!
A 10.8KW shower pulls 45amps at 240volts
A 40 amp MCB will allow 45amps to pass for quite a while before it trips. Sorry I don't have type 2 graphs to hand.
Looks like a 45A breaker is required, but before changing, it will need someone to positively check that
1. the cable that you have there is capable of carrying 45amps
2. the EFLI is within limits
3. that there are no other faults on the circuit
There is a ROUGH guide to cable saizes here
//www.diynot.com/wiki/electrics:cable_types:flatpvccables
That would give a first guess at the size of cable. Note that the size (10mm²) refers to the cross sectional area of the copper itself, not the dimension of teh cable sheath. And these vary from manufacturer to manufacturer.
Why did they shoehorn a Protek breaker in a Wylex board
A 40 amp MCB will allow 45amps to pass for quite a while before it trips. Sorry I don't have type 2 graphs to hand.
Looks like a 45A breaker is required, but before changing, it will need someone to positively check that
1. the cable that you have there is capable of carrying 45amps
2. the EFLI is within limits
3. that there are no other faults on the circuit
There is a ROUGH guide to cable saizes here
//www.diynot.com/wiki/electrics:cable_types:flatpvccables
That would give a first guess at the size of cable. Note that the size (10mm²) refers to the cross sectional area of the copper itself, not the dimension of teh cable sheath. And these vary from manufacturer to manufacturer.
Why did they shoehorn a Protek breaker in a Wylex board
A 10.8KW shower pulls 45amps at 240volts
A 40 amp MCB will allow 45amps to pass for quite a while before it trips. Sorry I don't have type 2 graphs to hand.
Looks like a 45A breaker is required, but before changing, it will need someone to positively check that
1. the cable that you have there is capable of carrying 45amps
2. the EFLI is within limits
3. that there are no other faults on the circuit
Why did they shoehorn a Protek breaker in a Wylex board
Don't worry about the graphs - they'll be useless to me!
I've called our electrician (not the one that installed it), and am waiting to arrange an appointment with him.
Are those checks fairly easy to do?
In simple English, you have a shower that when on full load requires 45A.
There will be occasions when the shower is not demanding full load, so 40A device will not break, there is also a period time were the device will hold before breaking when on full load or any demand between 40-45A.
If you have an electrician coming, they will inspect and confirm cable size and an de-rating factors, and the Zs will require shower cover removing and a few moments testing. I would test for insulation resistance.
Thanks guys.
I at least now have a bit more knowledge about the subject so I can have a sensible conversation with our electrician when he comes round.
Just googled the 40A thing on the 10.8kW Mira Sport max and it seems to be discussed in various places, including on this forum previously with many recommendations stating "40A will be fine".
I at least now have a bit more knowledge about the subject so I can have a sensible conversation with our electrician when he comes round.
Just googled the 40A thing on the 10.8kW Mira Sport max and it seems to be discussed in various places, including on this forum previously with many recommendations stating "40A will be fine".
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