In the bit of photo we can see, it looks rather like the dreaded loose neutral screw effect  again - the live wires at the top out of shot I presume are in tip top condition ? 

Are they implying by their statements about your consumer unit,  that their design is not adequately protected against a perfectly credible overload condition ?

I suggest collecting pictures of all the bits, as well as what wire sizes have been used.

I assume its one of these https://www.metermarket.co.uk/product/eastron-sdm230-mbus-mid-single-phase-direct-connected-100a-energy-meter.

15KW is a lot, but a 100 fuse and 230V suggests max steady load of 23kW, plus transient excursions above that - was the installation  not foreseeing a likely level of load ?

M

Thanks, I had a gas boiler and no EV at the time of installation

My incoming fuse is rated at 80A and I have no issues, but these meters are rated at 100A and one is on a circuit protected by a 50A breaker. I am having trouble with the maths saying it was overloading issues if I haven't been over 80A?

indeed and I'm not too clear what section is protected by what,

-but as described  I'm struggling to see

a) how they think you have overloaded it

b) if that really is what they think, why they designed you a system that could not handle the likely current.

And more likely if the neutral is burnt but not the live, that is a classic 'one loose screw' issue - both sides should look equally cooked as they carry identical current.

M.

But how do I fight one of the 'big boys' to admit they're at fault?

Andrew Smith 323 said:

I am having trouble with the maths saying it was overloading issues if I haven't been over 80A?

What was your energy input - from the Grid and PV, and potentially the battery?

What was your energy output - to home, grid, and potentially battery. It may be that the current flow somewhere was excessive.

Have you a circuit diagram please?

Andrew Smith 323 said:

But how do I fight one of the 'big boys' to admit they're at fault?

How much s it worth to fight? i.e. what is the possible benefit, and what has been lost. Balance the two.

Maximum power drawn for the year is 15.8kW during winter with heating on, batteries charging and EV charging.

Maximum power drawn for the year is 15.8kW during winter with heating on, batteries charging and EV charging.

Andrew Smith 323 said:

Maximum power drawn for the year is 15.8kW during winter with heating on, batteries charging and EV charging.

Was all of that through the 50 A circuit?

Regardless, if it's "overloaded" surely the design should conform to BS 7671, and hence arranged or protected so that overload is not likely?

Chris Pearson said:

How much s it worth to fight? i.e. what is the possible benefit, and what has been lost. Balance the tw

Agreed ... the sad thing is that it might cost more to get legal and technical experts involved, than it costs to repair the installation (and if appropriate correct any defects).

Import meter on 80A main fuse - blue wire

Export meter on 50A MCB - brown wire

Andrew Smith 323 said:

Import meter on 80A main fuse - blue wire

Export meter on 50A MCB - brown wire

That alone doesn't tell us where the current was flowing at any given points in time unfortunately.

However, a line conductor on one meter and neutral on the other does (without seeing the installation) make it appear that overload may have occurred (but without seeing further evidence, it's not conclusive).

As others have said, there are also a number of things that could cause this issue other than "overload" also - faulty equipment, or terminal not tightened to manufacturer's recommended torque (too tight or not tight enough), as well as other thermal considerations ... without seeing more evidence, it's not possible to do anything other than speculate.

The graph at the top shows total current drawn.

The garage is on a 50A breaker and has normal garage equipment plus the solar batteries and invertor