On 24/03/2021 20:05, Fredxx wrote:
On 24/03/2021 18:41, Theo wrote:
Tim+ wrote:
yy ARW wrote:

Loose connections.

+1.Â* 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.Â* It could be a
faulty
or fake MCB I suppose.

Cheers. Is there anything wrong with the positioning of the MCB as
suggested by Adrian?

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.Â* 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.Â* 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).

I may be wrong, but I thought each busbar was only rated for 60A for a
100A CU. With the presumption that the load would be split more or less
equally to both sides of the CU.

I am pretty sure the highest rated circuit should be next the RCD, next
to the main switch.

If I was the OP I would check the position of this MCB, after all it be
the one with the highest continuous current, and check with the CU
manufacturer's installation guide.


You are going back to the days of Wylex fuse boards. They always had
that rule and some of them had an extra fuse to the right of the main
switch for high loads.

The Wylex CU in the photo will have no problem with the layout of the
MCBs and is good for 100A.

--
Adam