This is the fuse box of a chap on Facebook who had a nasty experience after getting an 7kW EV charger fitted.
I don?t know enough to speculate on the cause but it there anything glaringly wrong here.
A couple more pictures.
Something seems to have got hotter than it should.
Tim+ snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@news.individual.net :
In the back of the switch it looks like the terminal screw is tightened onto the insulation..
The last MCB on the left is presumably the one lazily added for the car, taking the combined maximum current on that leg to over 120A, ignoring the rating of the previously installed RCD.
That fusebox not made for that overload on that leg, maybe it should have been installed on the right (full picture please!)
Looks like consistently under-tightened screws, on the consumer unit and the switch. Possibly on insulation as per JohnP's suggestion but good practice is to minimise the amount of bare copper.
It's not obvious if he's used 4mm cable?
It?s been replaced now and I don?t think there are more pictures.
Tim
By a different electrician I hope?
Loose connections.
Nope. Same one (which concerns me!).
Tim
Loose connection at the busbar, probably at the RCD, though could be at the first circuit breaker. There is a possibility that the busbar is not in the cage. It is possible on those breakers for the busbar to be touching the CB connection, but not tightened at all. Usually found soon after once things start flickering, but on a car charger there wouldnt be much of an indication of a poor connection. The switch is a common sight, burnt out due to a poor connection. With
10mm cable, and poor quality switches, it can be difficult to get a really tight connection. You think it is tight, twist the cable a little, and it is loose again.It doesnt help when the screw heads start splitting/ breaking, so you cannot tighten it enough anyway. Generally poorly installed.
Cheers. Is there anything wrong with the positioning of the MCB as suggested by Adrian?
Also, is that burnt out isolator switch suitable for a 7kW load over 8 hrs say (as might occur when car charging)?
Tim
Possible loose connections or a stray strand of conductor (or water ingress) to the switch. The damage to the mains switch looks like it was the root cause of the rather hot fusebox components.
Was it correctly rated for a continuous 7kW load?
If there is a fire and his insurers find out, there may be awkward questions to answer.
Most consumer unit manufacturers recommend placing high power circuits close to the switch to minimise length of busbar taking full load current. To minimise generation of heat within the enclosure.
Did you check if he used a torque screwdriver?
If he did, and he claim to have used the correct settings, he'll effectively be absolved from blame.
Have all the MCB levers been joined and cable tied in the on position?
A total of a possible 120A through a 80A RCD?
Screws to bus bar not tighted to the correct torque?
OK - no. I had just zoomed in and that's what it looked like.
+1. Not appropriately torqued I would guess. (a common problem with electric showers, which tend to run for a much shorter time)
It's possible a load >>32A was applied which melted the isolator and cooked the RCD, but I would expect the MCB to trip for that. It could be a faulty or fake MCB I suppose.
It really depends on how the charger is set up, which we can't see. Chargers can be set to monitor the outputs from the consumer unit and limit the current if another big load like a shower or cooker is in use, so that the maximum current of the supply is not exceeded. Alternatively the electrician can apply diversity to set the charger output to a lower current.
I don't know the rating of that busbar, but I'd expect it to carry the full current from the main switch if it were wired that way. So I don't think an
80A RCD next to a 32A MCB should cause any problems (apart from perhaps running warm and gradual cookage over time).It appears to be this one, which is rated at 45A which would be fine for a
32A/7kW single phase supply:Theo
Not necessarily. He can claim what he wants but if there is evidence to the contrary the court will look at all the facts and circumstances and determine on the balance of probabilities what actually occurred.
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