shower on 6mm for future

[i=p/u]

i was asked to pull in a shower cable and leave in wall for future as customer has been roked into other work, so makes sense now as they have the room.

9.5kw shower on 6mm is fine according to osg upto 43m on ref method c. i only have an 8m run and is in rafters with kingspan but kingspan wont be touching it. it has 150mm rafter with only 100mm kingspan..
so at least a 50mm gap around cable
i said its dead on for 8.5kw shower but i do think 9,5 will be fine aswell.


thoughts

 

[i=p/u]

also when i do adiabatic and use 5 seconds im getting 41 ? why

 

[Richard Burns]

If the cable is not in or under any insulation then 6mm should be OK for 9.5kW.
I get 3.88 with the adiabatic equation (for a 40A BS60898).

 

[MKS]

ditto to the above

 

[JUD]

I get 3.88 with the adiabatic equation (for a 40A BS60898).

How do you get that without knowing the PFC of the circuit? :bucktooth:

 

[Lee Marshall]

I'd be tempted to just put in 10mm cable then all is covered e.g wanting a 10.8kw shower in the future

 

[i=p/u]

well righard there is only a 2.5mm in the 6mm t&E

If the cable is not in or under any insulation then 6mm should be OK for 9.5kW.
I get 3.88 with the adiabatic equation (for a 40A BS60898).

- - - Updated - - -

200 x 200 for the 40A breaker

How do you get that without knowing the PFC of the circuit? :bucktooth:

 

[JUD]

Richard has used the Ia value for the breaker (200A) which would cause the breaker to operate in 0.1secs.

S = √(I² x t) ÷ k
S = √(200² x 0.1) ÷ 115 = 0.55

However the correct value to use is the actual fault current that could flow in the event of a fault (Ipf = Uo ÷ Zs) which could be a lot higher if the Zs is low enough.

 

[joe j]

Stick 10mm in and you will definitely be ok for the future. It may be a bit of a git to get into switch terms but it won't burn if it gets covered.

 

[Johnuk]

use 10mm,

 

[i=p/u]

ive already put in 6mm as i knew this would run an 8,5kw and was 40 quid cheaper per 50m roll.

 

[Guitarist]

Tell em to use a 7.5KW shower if they need one. Good enough for my kids AND it saves water to boot....

 

[Moses]

Tell em to use a 7.5KW shower if they need one. Good enough for my kids AND it saves water to boot....

I concur.

8.5Kw is big enough even in very cold weather.

Is Greaner than a 9.5/10.5Kw in electric and water.

 

[telectrix]

Tell em to use a 7.5KW shower if they need one. Good enough for my kids AND it saves water to boot....

and what thhen do you do with the water in yer boot? :drummer:

 

[Guitarist]

and what thhen do you do with the water in yer boot? :drummer:

Pop some tadpoles in

 

[telectrix]

mmm tadpole wellington. makes a change from beef.

 

[i=p/u]

still cant get me adibiatic right for this shower.. its a tn-c-s so say max of 0.35 ohms and its 10m max so say 0.45 as calculated zs = 511A

511 x 511 = 261121 x 5 = 1305605 / 115 =11353 and the square root off 11353 = 106 which is wrong.

 

[Risteard]

Why do you think your protective device will take 5 seconds to operate?

 

[derek preece]

Are you assuming a 5 sec disconnection time for a 60898?

 

[i=p/u]

well its over 32A