Shower issues

[MICH43L]

I swapped out my old shower for a 10.8kw one from screwfix.

Worked for a while, but at the pull switch it's melting the cables going TO the shower and tripping the breaker.

The full run is as follows:

• About 9-10m of 6mm2 from mcb to a junction box above the switch.
• 10mm2 from the junction box to the switch. (about 15cm - no idea why?? ).
• BG 45A Pull switch
• 6mm2 coming out of the switch to the shower.

I think the whole run needs replacing for 10mm2. But wondering if the issue is more likely to be the switch, or the disparity between the short run of 10mm2 in and the 6mm2 going out.

 

[EFLImpudence]

If the melting wire(s) is/are just at the switch, then this will be because of loose connection(s).

 

[Taylortwocities]

What size is the MCB?

 

[MICH43L]

What size is the MCB?

It's a 32A mcb

EZ9F16132

 

[Taylortwocities]

As EFLI says, IF the only sign of overheating is at the switch, then the larger current drawn by your new shower has uncovered what was probably a bad termination At the switch, or the switch itself.
But note that a 19.8KW shower will pull around 47amps, the 32A MCB will hold in so long as you take short showers. Any more than a couple of minutes and it will trip (hopefully) before the 6mm cable catches fire.

 

[Harry Bloomfield]

I think the whole run needs replacing for 10mm2. But wondering if the issue is more likely to be the switch, or the disparity between the short run of 10mm2 in and the 6mm2 going out.

Nothing to do with the short run of 10mm, most likely due to poorly made connection to the switch or a poor quality / faulty switch.

 

[securespark]

The best switch by far is the Crabtree round one.

https://www.screwfix.com/p/crabtree-50a-1-way-pull-cord-switch-white/90597

 

[winston1]

Or just bypass the switch. There is no requirement to have one after all.

 

[Harry Bloomfield]

Nothing to do with the short run of 10mm, most likely due to poorly made connection to the switch or a poor quality / faulty switch.

Are you turning the switch on and off perhaps, every time you use the shower? It is unnecessary and causes a great deal of wear and tear on the switch. The switch is there only for isolation, when you or someone else is working on the shower.

 

[bernardgreen]

Or just bypass the switch. There is no requirement to have one after all.

Winston overlooks the safety that an isolator provides when the shower decides to self cremate.

Winston, you have been told several times that going sopping wet and possible covered in soap suds to the consumer unit to find the shower MCB and switch it off is a hazardous activity.

 

[Taylortwocities]

But perhaps its a path that we might encourage him to take!

 

[winston1]

Winston, you have been told several times that going sopping wet and possible covered in soap suds to the consumer unit to find the shower MCB and switch it off is a hazardous activity.

Don’t tell me. Tell those that write the regs.

 

[securespark]

Just because the regs say you don't have to have an isolator doesn't mean you can't fit one.

The regs are a minimum and can be exceeded.

Let me tell you a little story. I hope you are sitting comfortably.

When the 14th Edition was introduced in 1966, they went into great detail and there was much criticism because it wasn't so much a book of regulations but an instruction manual, allowing anybody to have a go at wiring.

Nowadays, the regs are less of an instruction manual and the users have to apply their grey matter more.

Edited for clarity.

 

[SUNRAY]

Don’t tell me. Tell those that write the regs.

I'd like to tell a little story too, a elderly couple got into the habit of a prolonged holiday in the winter, they had a lovely long cruise and were looking forward to a lovely cupof tea on their return. Instead they opened the door to find every single surface in the house was covered with thick black mould.
The shower unit was one of the lovely swish super duper overpriced electronic things with a series of buttons for cold and several heat settings. It had gone wrong and been running non stop for a long time, the least of their problems was the £2K leccy bill. There was no flooding involved as it had all gone down the drain but the mould was so bad that even the floor joists were replaced.

 

[winston1]

I'd like to tell a little story too, a elderly couple got into the habit of a prolonged holiday in the winter, they had a lovely long cruise and were looking forward to a lovely cupof tea on their return. Instead they opened the door to find every single surface in the house was covered with thick black mould.
The shower unit was one of the lovely swish super duper overpriced electronic things with a series of buttons for cold and several heat settings. It had gone wrong and been running non stop for a long time, the least of their problems was the £2K leccy bill. There was no flooding involved as it had all gone down the drain but the mould was so bad that even the floor joists were replaced.

They went away in winter and didn't turn the water off?