8.5kw shower wires in 4mm, burnt terminals

[robo83]

Just arrived at a job, 45amp shower isolator completely burnt out.

Checked cable and it's 4mm tne in trunking to 8.5kw triton riba shower on a 32amp mcb. Cable run is 5meters.

This was a new circuit installed only a few months ago. I expect loose connection on isolator causing burnt terminals.

I am going to request cable uprated to 6mm, anyone else make any sense why a 4mm was used?

 

[Octopus]

what type of switch was it? Pull cord or wall mount?

FWIW 4 mm wasn't big enough to start with.

 

[Pete999]

That's all he had in the Van, or quite obviously he has miscalculated.

 

[Octopus]

or quite obviously he has miscalculated.

Or did he think at all - 4mm T&E was never going to be big enough IMHO

 

[Pete999]

Ah sid it I'll stick some 4mm2 in, it'll be OK til it burns out, I'll be long gone by then, or something to that effect, or he's aDilbert.

 

[Des 56]

He put the 4.0mm on a 32 amp mcb,it was supplying a 7KW unit, its since been changed for the 8.5KW by the user

Fantasy thinking I suppose but it often happens,think of 6.0mm and the purchases of the monster energy guzzlers by the ladies swooning over their size in B+Q

 

[Pete999]

He put the 4.0mm on a 32 amp mcb,it was supplying a 7KW unit, its since been changed for the 8.5KW by the user

Fantasy thinking I suppose but it often happens,think of 6.0mm and the purchases of the monster energy guzzlers by the ladies swooning over their size in B+Q

Deleted

 

[Octopus]

Who in their right mind would run in a new dedicated shower circuit in 4mm?

 

[telectrix]

Who in their right mind would run in a new dedicated shower circuit in 4mm?

someone who calculated that it was adequate for the load it served.

 

[robo83]

Just spoke to landlord.

Landlord purchased shower first and informed her other electrican what she had purchased, he then went and installed supply.

 

[robo83]

This was condition of terminals when I arrived, MCB & RCD still in closed position.

 

[Octopus]

Just spoke to landlord.

Landlord purchased shower first and informed her other electrican what she had purchased, he then went and installed supply.

In which case landlord needs to get said spark back to replace switch and cable ......

 

[Rpa07]

Shakes head!

 

[Pete999]

This was condition of terminals when I arrived, MCB & RCD still in closed position.

View attachment 37612

Oh nice

 

[Rpa07]

And it's not the neutral this time!

 

[westward10]

I suspect the root cause of this was a loose connection and not conductor csa although it is obviously undersized.

 

[robo83]

I've told llthe landlord to get other electrican to call me if he has any issues returning to sort, also when I undid the isolator Fascia the cables just fell out the back.

I checked over the board before I disconnected the supply and some of the terminals were LOOSE :/

 

[telectrix]

but was not undersized for the 7kW shower, and was suitably protected with a 32A MCB. a bit like the chandelier i just repaired for a customer. 105VA transformer supplying 10 x 10w G4 lamps. he'd fitted 10 x 20w G4s and wondered why the transformer failed.

 

[robo83]

The landlord said they told the electrican what shower they were getting. And the sparks installed it with the cable, he must have known it was 8.5kw.

 

[telectrix]

The landlord said they told the electrican what shower they were getting. And the sparks installed it with the cable, he must have known it was 8.5kw.

even so, the 4mm would have handled that 8.5kW. it's down to poor terminations.