advise me on shower wiring please

[kenny1]

hi everyone. i'm hoping someone here can advise me on shower wiring.
i have a 8.5kw shower, my cabling says 2x6+2.5 on it......i take it thats 6mmsq cable???

it will be running from a wylex cu with rcd main switch = 80A 30mA
with a nsb40 40amp mcb.

am i correct in thinking the 40 amp mcb is enough? i think it is as 8.5kw=8500 / 230v = 36.9.

i have ran the cable from the 40amp mcb into a 45amp double pole switch then from there continued on into the shower. i am a bit concerned as the cable seems to heat mildly after about 5 mins of the shower running.

thanks.

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Moderator's note:
I have changed the thread title to make it meaningful.

Mod Rupert
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[Chivers7]

How far is your run?

What does it go through to get to the shower?

 

[BigJon]

I'd be tempted to run a 10mm cable in, for future installs if nothing else.
I'd also recommend you have RCD protection

 

[DESL]

Cable will get warm.

6mm2 cable of say 10 m length will give a volt drop of ~3 volts and at 37A will dissipate 110 watts in heat.

Bigjon OP has 80A 30mA RCD mainswitch

 

[kenny1]

the cable run is about 9 metres, and goes along the wall in plastic trunking. it also goes through 2 plasterboard walls.

also is it safe to change over these mcb's???

here are pics to help.

i want to change the b32 for the b40............in the pics the b32 is the one on the left.


my cu-

in this pic i have put the b40 in place where the b32 was-

can i swap the b32 for the b40?

the b40 has the black clip

hope the pics help.

 

[DESL]

Why do you want to change MCBs as from pic the 40A is feeding the shower.
Or are you wanting to use 40A for cooker?

 

[Chri5]

Why are the lights and ring on the same MCB

Why isn't there a blanking plate on position 8

Why are all the MCB's tilted

 

[kenny1]

there was a b32 originally where the b40 is now............i took the b40 back out just now until i know if its safe to use.

 

[ayen]

Lights + sockets on one 32 amp mcb????/
Of course you have notified your LABC and payed relevent fee.????

 

[Spark123]

Lights + sockets on one 32 amp mcb????/
Of course you have notified your LABC and payed relevent fee.????

Although Part P doesn't apply north of the border?
Still agree the 32A sockets/lights needs looked into, what is the other CU for below?

 

[ayen]

good spot

 

[ayen]

But is the install being tested ? Regardless of location IEC should be produced to comply with the regs.

 

[kenny1]

i've just moved into the house, everything in the cu is the way i found it.
still needing answers to my above questions.....and the cu below is for storage heating.

there are 2 cables coming out the sockets and lighting mcb......shoould it be like that?

 

[Chivers7]

i have a 8.5kw shower, my cabling says 2x6+2.5 on it......i take it thats 6mmsq cable??? Yes

it will be running from a wylex cu with rcd main switch = 80A 30mA
with a nsb40 40amp mcb. Yes

am i correct in thinking the 40 amp mcb is enough? i think it is as 8.5kw=8500 / 230v = 36.9. Yes

i have ran the cable from the 40amp mcb into a 45amp double pole switch then from there continued on into the shower. i am a bit concerned as the cable seems to heat mildly after about 5 mins of the shower running. See DESL first reply

thanks.

+++++++++
Moderator's note:
I have changed the thread title to make it meaningful.

Mod Rupert
++++++++++

I'd hope that Socket+lights fuse is for a Ring Final circuit which perhaps feeds some kind of lighting - maybe external via a fused spur? (Hence the + lights), but without seeing it it's pure guess work. I'd suggest you turn off the B6 fuse and check if the lighting is via this and not just a smoke alarm.

This really needs confirming.

 

[kenny1]

i put every light on in the house, then turned off the b6 (smoke alarm)............every light stayed on. only the smoke alarm went off.

this is how i found the cu's when i moved in.

the mcb marked shower is empty.....can i remove it and replace it with the 40 mcb i have? oh and before i forget.......on the cu i only have one earth rail and one N rail.......is that ok?

this is the cu below: