8.5kw shower wires in 4mm, burnt terminals

[Ian1981]

A job I'm starting a new build bungalow has been specified 16mm twin and earth for 10.5kw shower complete with a wall mounted isolation switch outside of the ensuite, which is a stud wall!
Oh the joys.

 

[Lee42]

A job I'm starting a new build bungalow has been specified 16mm twin and earth for 10.5kw shower complete with a wall mounted isolation switch outside of the ensuite, which is a stud wall!
Oh the joys.

Good luck.

Is that due to cable running through alot of insulation?
Never seen a 16mm at a shower before.
At least you can install a double 47mm metal box in the stud partition

 

[Ian1981]

Apparently 3 layers of insulation are going in so looking at reference method 101 even 16mm twin only pulls 46 amps reference method 101.
At 10.5kw I'm looking at a loading of 43-44 amps so the 16mm will be able to handle it.
I need to consult the builder and maybe request some boards are fixed above the insulation so a 10mm can be clipped above the insulation.
They won't budge to a lower rated shower tho.
Doubt I'd even manage to fit a 47mm box in the wall as the studs are only about 50mm deep

 

[Lee42]

That is a narrow stud
Thankfully always 4x2 with the joiners we work with.
Would not like to terminate a 10mm in anything less than a double 47mm box.
To be honest don't like wirring showers fullstop

 

[Lee42]

Apparently 3 layers of insulation are going in so looking at reference method 101 even 16mm twin only pulls 46 amps reference method 101.
At 10.5kw I'm looking at a loading of 43-44 amps so the 16mm will be able to handle it.
I need to consult the builder and maybe request some boards are fixed above the insulation so a 10mm can be clipped above the insulation.
They won't budge to a lower rated shower tho.
Doubt I'd even manage to fit a 47mm box in the wall as the studs are only about 50mm deep

Don't like using them, but could u fit a 47mm faster fix box to give u that extra room.

 

[Ian1981]

That is a narrow stud
Thankfully always 4x2 with the joiners we work with.
Would not like to terminate a 10mm in anything less than a double 47mm box.
To be honest don't like wirring showers fullstop

I'll get round it as I really don't want to be installing 16mm but it's not mine or my company's spec
4mm ring circuits as well.

 

[Ian1981]

Don't like using them, but could u fit a 47mm faster fix box to give u that extra room.

I've used them on 10mm never on 16mm
I can see the wall buckel as I try to push the switch back

 

[davesparks]

If it is already known that there will be that much insulation the. The electrical installation designer should first be trying to find a way to keep the cables out of it rather than plan for them to be buried in it.

 

[Darkwood]

If there is any kind of airing cupboard then a suggestion if re-routing the cable isn't an option would be a contactor operated by a lighting pull switch, cable size thus of no concern then. If the designer has issue with this then give then let them try terminate 2 x 16mm T&E into a standard shower switch and deep box.

 

[Wilko]

If the designer has issue with this then give then let them try terminate 2 x 16mm T&E into a standard shower switch and deep box.

So true DW. First one I checked was Crabtree 50A and they won't accept bigger than 10mm2.

 

[Ian1981]

So true DW. First one I checked was Crabtree 50A and they won't accept bigger than 10mm2.

View attachment 37643

The spec is deta accessories.
So I'll have a look , think they only go as far as a 45 amp DP switch.
Not sure on terminal size yet

 

[telectrix]

16mm for a bloody shower? bloody madness. these insulation freaks need to work round us and keep it away from cables. not vice versa.

 

[Pete999]

16mm for a bloody shower? bloody madness. these insulation freaks need to work round us and keep it away from cables. not vice versa.

Can only think running and terminating a 16mm2 T and E would be complete barsteward

 

[Des 56]

If I can manage to get my brain into gear,I think I will look for a logical regulation which frowns on such practices of using larger than life cable sizes on everyday accessories,extra naughty I believe

 

[telectrix]

slightlyoff topic, but hre's something that has been bugging me for ages.

when applying the temp. factor ( 1.2 ) to your loop impedance as per osg., why apply it to the whole Zs value and not just to the R1+R2, when the supply cable from sub-station is never going to approach anything like 70 deg. ????

thoughts???