Yesterday’s callout - a close call

[daveb]

hi folks, thought I’d share this...

Called out to a customer of mine yesterday, said that her shower switch had been making a smell if shower had been on for 10mins. Went there expecting to be a loose neutral like I’ve seen before.

The shower was a 9.5kw that had been installed and once I looked into the circuit it was a 45 amp rewireable fuse with only a 6mm cable! Connections were tight after all but the neutral side was very very burned on the load side.

As a temporary fix, I changed out the wire for 30 amp wire in the short term. Explained this to the customer as I put an amp meter on and ran the shower as she’d had it set. It ran to 42 amps - and the fuse wire held up! Set her shower to medium setting and ran the meter again and was only pulling 23 Amps.

So, if there was ever a reason to explain to customers why to upgrade their boards from fuse wire - this is a good story right here. Very dangerous and could have been a fire.

 

[Madocks]

Are you going back to sort the permanent fix?

 

[Andy78]

The fuse wire is not at fault, or the board. Are you saying you left this burnt cable in place and put a smaller fuse wire in and said it could be used safely ?

 

[daveb]

Jeez, I see the righteous police are straight onto this one eh? . “Temporary fix” means “temporary” until the job gets done properly!

The cable was re-terminated and switch replaced. The customer wants a quote for replacing the shower cable to a 10mm one and changing out the consumer unit.

This was 5pm on a Saturday afternoon. There was no need to just disconnect her shower completely when there was a work around as a “temporary” fix when I get back to replace

 

[Dillb]

Sorry but a quote doesn’t mean the customer will get the work done. 2-3 weeks of the showers working fine means that spending £100s will not achieve anything that doesn’t already work.

 

[Andy78]

Ah yes, the "it can't be wrong because it is only temporary" thought process.
Think I'll excuse myself from this thread.

 

[daveb]

So you’d rock up to a customers house -disconnect their shower and walk away until you tell them you’re returning to replace their shower cable? If it was a modern day board - you’d not just de rate the MCB in the meantime to match the cable size as a temporary fix? Exactly

 

[Dillb]

So you have admitted the cable is under rated for the maximum load, yet have left it in service? If you think that fuse wire will protect the cable then I suggest you look at the relevant curves for it and see how long it would take for it to operate at the maximum load?

 

[telectrix]

all depends on the installation method of the 6.0mm. if method C, then it's OK for 47A. ( and that's IET's pessimistic safe load ).

 

[daveb]

The circuit has been de-rated and the customer has been told to leave her shower at medium setting until the changes can be made. I don’t know where you guys come from but up here you can’t get a drum of 10mm cable or a new consumer unit at 5pm on a Friday.

 

[Dillb]

Very true Tel, but We can only work on what the OP tells us, which is that the cable needs changing to 10mm which mean he must of carried out the relevant calculations.

 

[telectrix]

The circuit has been de-rated and the customer has been told to leave her shower at medium setting until the changes can be made. I don’t know where you guys come from but up here you can’t get a drum of 10mm cable or a new consumer unit at 5pm on a Friday.

screwfix open till 7.00pm.

 

[Dillb]

The circuit has been de-rated and the customer has been told to leave her shower at medium setting until the changes can be made. I don’t know where you guys come from but up here you can’t get a drum of 10mm cable or a new consumer unit at 5pm on a Friday.

Doesn’t matter you have admitted leaving the circuit in a situation which could lead to a fire. Why you fitting a new DB? Could you not just fit a RCD next to the existing board?

 

[daveb]

And for the record - the quote I need to do for her is to replace her whole consumer unit or to just install a new 2 way board for the shower circuit. Along with the cable upgrade obviously

 

[Dannyg8810]

Id of made safe of left disconcected if there’s no RCD protection...... in this situation any how .

But that’s just my opinion I haven’t seen the situation first hand like the OP