Shower wiring

[yanster]

Hi guys,

whilst putting some more insulation in my attic i came across the wiring for my shower in the bathroom.

As my knowledge of electricals is minimal i thought i'd seek your advice.

The shower is an 8.5kw with an isolating pull switch, the wiring from the pull switch to the actual shower is quite thick cable and i'm guessing either 6mm or 10mm (same thickness as to my cooker by the looks of things) but the wiring that goes to the pull switch is thinner - i'd think 4mm - definitely not 2.5 but doesn't seem thick enough for 6mm or 10mm.

After the discovery i went back to the fuseboard to find this wire and its wired into a 30amp fuse.

Having had a look through the forum it seems that 6mm is minimum for showers, and wired into a 40amp fuse.

Can anyone say if my 8.5k shower is safe to use as is?

of course it would probably be better that i should be looking at replacing the wiring but will it be ok to use on its current setup.

Cheers for any advice even if it is bad news.

 

[FingRinal]

Outer diameter of cables with a sheath can vary. Older cable is generally thicker than more modern cable. Without reverting to direct physical measurement, one can't be sure.

As the cable is protected by a 30A fuse, I doubt it poses an immediate danger. If a portion of it is 4mm and is completely surrounded by loft insulation, it might pose a danger soon enough though, especially if anyone enjoys long showers.

As you have doubts, it might be worthwhile getting it looked at - if you could find someone that is. Probably need to have it rewired to be sure and to get someone to look at it!!

 

[yanster]

thanks for that.

fortunately theres no insulation around it - as i found when moving the loft boards it just sits in an empty space.

so 4mm on a 30amp fuse isn't a disaster waiting to happen?

will it affect the performance of the shower?

 

[FingRinal]

It doesn't compy with the Regs but it's unlikely to cause a problem in normal use. It might if the shower were replaced with one of a higher rating.

 

[securespark]

As the cable is protected by a 30A fuse, I doubt it poses an immediate danger.

What amount of overload will a 3036 withstand?

If the 4mm² is in contact with loft insulation, that can effectively halve the CCC.

I have known 10.5kW showers on a 30A 3036 "work" for years before giving up the ghost, but by that time, the board was actually catching alight.

I appreciate this is an 8.5kW shower, but we are talking 4mm² & possible loft insulation plus a CPD with a potentially prehistoric reaction time.

Still think the following is best advice?

FR wrote: It doesn't compy with the Regs but it's unlikely to cause a problem in normal use. It might if the shower were replaced with one of a higher rating.

 

[FingRinal]

As the cable is protected by a 30A fuse, I doubt it poses an immediate danger.

What amount of overload will a 3036 withstand?

Please look up the definition of 'immediate' danger.

If the 4mm² is in contact with loft insulation, that can effectively halve the CCC.

Perhaps you could post the entire paragraph instead of resorting to BAS's selective cut and pastes.

I have known 10.5kW showers on a 30A 3036 "work" for years before giving up the ghost, but by that time, the board was actually catching alight.

And years and years constitutes an immediate danger does it? And 2kW less loading adds to that immediate danger does it?

I appreciate this is an 8.5kW shower, but we are talking 4mm² & possible loft insulation plus a CPD with a potentially prehistoric reaction time.

Still think the following is best advice?

FR wrote: It doesn't compy with the Regs but it's unlikely to cause a problem in normal use. It might if the shower were replaced with one of a higher rating.

AFTER we've established that the cable isn't surrounded by insulation. I presume you lost concentration whilst reading the whole thread. Maybe you should work on these skills.

I understand you're a BAS groupie. Even BAS's own 'legal' mumbo jumbo warns against scaremongering electricians who don't know what they are doing. Does this include you?

Also, you appear to be confused with overload current and fault current. I suggest you look these up as it is basic stuff.

Prehistoric reaction time? What do you mean?

I've seen showers run off 2.5mm for years. It's been just about to go but it has never the less lasted for years.

Perhaps we should resort to panic and tell the OP that they are lucky someone hasn't died already, or lucky that the house hasn't burnt down, or that the next time someone uses the shower they will die.

So, the cable appears to be clipped direct. 4mm (if it IS 4mm) is good for 37A on a 35A load protected by a 30A fuse. OK the fuse has a correction factor. I'm sure you can do the maths and hopefully reach the conclusion that it doesn't comply with the Regs but it is unlikely to cause a problem in normal use. It would be a Code 2 on a PIR if you are familiar with PIRs. Of course, one could install a plug[in Type B mcb (32A) an eliminate the correction factor.