max volt drop to sub board

[The apprentice]

max volt drop to sub board 3 core swa 137 meters ?

 

[andyb]

Twifty

 

[andyb]

+ or - 3%

 

[andyb]

Or rule of tummy

 

[Strima]

Volt drop applies to end of circuit so you need to factor that in, not just to the sub board.

 

[Andy78]

That completely depends on what volt drop is required for the final circuits from the sub board. The maximum permitted volt drop for a circuit should be from origin to final circuit end. The designed volt drop for the sub main should take this into account.

 

[casperLennon]

What a very polite way to ask a question

 

[The apprentice]

That completely depends on what volt drop is required for the final circuits from the sub board. The maximum permitted volt drop for a circuit should be from origin to final circuit end. The designed volt drop for the sub main should take this into account.

the sub board is for a static caravan fed from a 3 phase board in a garage 137 meters away the cable will be surface 25 mm 2 core swa fe from a B50 ib did the maths and it worked out that iam not within the limits was just looking for advise thanks a lot guys sorry about the way i asked the question

 

[westward10]

As Andy states in #6 the vd is from your source of supply to the furthest point of any lighting circuit so applying 3% to the submain is not likely to satisfy this requirement. Allowing 2% for the submain gives you a further 1% for the final lighting circuit/s. Your cable needs to be at least double your 25mm.

 

[ruston]

the sub board is for a static caravan fed from a 3 phase board in a garage 137 meters away the cable will be surface 25 mm 2 core swa fe from a B50 ib did the maths and it worked out that iam not within the limits was just looking for advise thanks a lot guys sorry about the way i asked the question

A saying up here lol - Shy bairns get nowt.

 

[westward10]

Your next issue is the use of a 50A circuit breaker, terminating a 25mm is going to be difficult but go above this is is not going to be feasible especially the neutral and cpc.

 

[The apprentice]

Your next issue is the use of a 50A circuit breaker, terminating a 25mm is going to be difficult but go above this is is not going to be feasible especially the neutral and cpc.

if we had 10mm swa on a b50 supply

 

[Pete999]

if we had 10mm swa on a b50 supply

Is that a question or a suggestion?

 

[westward10]

if we had 10mm swa on a b50 supply

You are going backwards there with regard to volt drop.

 

[Pete999]

You are going backwards there with regard to volt drop.

Agree, I thought that, but nah, that can't be what he means, seems to me that the OP is either not understanding your previous or ignoring it, and just focusing on the practicalities of just connecting a cable, with no regards to VD whatsoever, hope I'm wrong.