10.5kW Shower Cable Size

[Noob2013]

Hi all,

Would a 10.5kW Shower require 10mm or 16mm twin and earth?

I've been doing cable calculations at college and im not 100%.

Cable Length = 20m
Protective Device = 50A
Wiring method = Above plasterboard ceiling not exceeding 100mm insulation

I belive 10mm is sufficient but my calcs are indicating 16mm which I've never heard of for a shower circuit.

Much appreciated

 

[Pete999]

Can you include your cable calculations, it would be more helpful if you could.

 

[GMES]

As Pete says, please offer up how you come to your answer, then the guys will help you out.

 

[Noob2013]

I did 10500 ÷ 230 = 45.6 A

Then I used;

In
Ca Cg Ci Cf

50
1.0 x 1.0 x 0.78 x 1

= 50 ÷ 0.78 = 64.1 A

Table 4D5 shows 10mm can carry 45A with this wiring method.

I've now confused myself because that table shows 2.5mm can only carry 21 A

:S

 

[Noob2013]

I also used TLCs Cable Size Calculator out of curiosity and it says 16mm.

 

[Scotford14]

Its due to the factors.

By dividing IN by 0.78 you are effectively sizing a cable that will handle a load 20% bigger due to the insulation FACTOR. Ci

 

[telectrix]

move the insulation away from the cable.

 

[Engineer54]

Its due to the factors.

By dividing IN by 0.78 you are effectively sizing a cable that will handle a load 20% bigger due to the insulation FACTOR. Ci

In other words, ...DON'T run the cables surrounded by insulation material, either clip them on top of the loft joists or at the top of the sides of joists. It's not rocket science when all said and done!!

 

[telectrix]

it's getting bogged down by technicalities while ignoring common sense.

 

[Octopus]

And if you plan to install an isolation switch just ake sure you suggest a pull cord and allow for the Crabtree 50A unit.

 

[D Skelton]

Hi all,

Would a 10.5kW Shower require 10mm or 16mm twin and earth?

I've been doing cable calculations at college and im not 100%.

Cable Length = 20m
Protective Device = 50A
Wiring method = Above plasterboard ceiling not exceeding 100mm insulation

I belive 10mm is sufficient but my calcs are indicating 16mm which I've never heard of for a shower circuit.

Much appreciated

Just to throw a spanner in the works, a 6mm cable will be fine for a 10.5kW shower if no derating factors apply, such as insulation or ambient temperature.

Just goes to show you how running cables in insulation is a bad idea!

 

[Octopus]

If you need to run a new cable I would give the customer the price for 6mm and the "upgrade" to 10mm and let them decide. The upgrade isn't much!

 

[Simonslimline]

If you need to run a new cable I would give the customer the price for 6mm and the "upgrade" to 10mm and let them decide. The upgrade isn't much!

I think this is homework and not actually a real job. The profile says Apprentice.

 

[Simonslimline]

Hi all,

Would a 10.5kW Shower require 10mm or 16mm twin and earth?

I've been doing cable calculations at college and im not 100%.

Cable Length = 20m
Protective Device = 50A
Wiring method = Above plasterboard ceiling not exceeding 100mm insulation

I belive 10mm is sufficient but my calcs are indicating 16mm which I've never heard of for a shower circuit.

Much appreciated

Seeing as you are an apprentice, i advise gaining access to the trainee section mate.

I am sure you will find it very useful for future questions.

 

[telectrix]

apprentice?right. then the answer is to use 1.5mm cable so you can observe and study overload effects on cable .