Can I use a 4mm T&E for a 7.5Kw shower?

[louis butler]

The cable is installed in 3 metres of trunking, 3 metres clipped direct, and 5metres in the joist space with no insulation,

 

[littlespark]

Will you lot stop saying “jobby”

There’s Scotsmen here, you know.

 

[telectrix]

jobby,jobby,jobby.

 

[pc1966]

Based on a 240V, 7.5kw shower and a total length of 16M of 4MM2 cable and assuming cable resistance at 4.3mohm/M then my (rusty) calcs give a current flow of 30.975ohms and a shower output of 7.368kw and a voltage drop of 2.13V through the cable resulting in a cable heat loss of 65.94watts or 4.12watts/meter of cable.

So is 4MM2 suitable??.

Only if it keeps cool enough.

That is one of the 3 critical tests for cable choice:

• Current carrying capacity (combinations of resistance, insulation temperature limit, ambient temperature, and thermal insulation "method")
• Voltage drop (resistance and length)
• Zs for Automatic Disconnection of Supply (resistance, length, protective device and supply impedance)

Should I don the Cardinal Ximénez outfit and summon Cardinal Fang now?

 

[DPG]

I love these convos you have to put every detail in about every product or operation. The science behind it or the physics, the calculations like you designing an electrical installation right from your phone.

If you put anything in laymans terms someone is quick to point out a fall or bite ?

Have fun guys another forum i wont be on again.

You lot are way better electricians...well done

I notice you've been back on the forum this evening. I knew you'd be back.

As I say, stick around - there's a lot of knowledge on here.

 

[GLENNSPARK]

Only if it keeps cool enough.

That is one of the 3 critical tests for cable choice:

• Current carrying capacity (combinations of resistance, insulation temperature limit, ambient temperature, and thermal insulation "method")
• Voltage drop (resistance and length)
• Zs for Automatic Disconnection of Supply (resistance, length, protective device and supply impedance)

Should I don the Cardinal Ximénez outfit and summon Cardinal Fang now?

Installation method and ambient temperature takes paramount for most normal fixed wiring applications as it dictates everything else...