Sub main question

[Jimmyb]

Hi all, been to look at a job on a farm on Friday they want a extra socket for welder, any way just wanted your opinions on this submain,
the supply is fed by a c50mcb on 16mm 2c for 15m to dis board, from there it is feeds 3 sheds all about 40meters away. the thing im not to sure on is there is only 2 feeds from the dis board, 1 for shed1 and the other that feeds shed2, but for the supply to shed3 they have looped in and out of the main switch does this not need a mcb inside shed2 boards ?
please advise

jimmy

 

[not clever]

Yes it does.

 

[ian.settle1]

Yes it does.

Have seen it before where 2 distribution boards are supplied from 1 sub main with the second distribution board off the incoming side of the isolator.

 

[JonAW]

I do not see the problem with looping from the incoming side of a mains switch to another mains switch as long as the cable size is appropriate for carrying the required current and the appropriate protection device is used at the beginning of the 'radial'. Surely there is no difference using this method as there is when installing a radial of sockets.

Please correct me if I am wrong.

 

[mechelec]

I do not see the problem with looping from the incoming side of a mains switch to another mains switch as long as the cable size is appropriate for carrying the required current and the appropriate protection device is used at the beginning of the 'radial'. Surely there is no difference using this method as there is when installing a radial of sockets.

Please correct me if I am wrong.

I have to agree. Used this method before myself.

 

[Darkwood]

It can be pulled as incorrect if the front end switch is physically too small to accept both cores comfortably (appropriate crimps may be needed) also the submains must be marked up with regards to supplying two dist' boards in this manner.
Another point is the rating of the looped switch must be able to withstand the current of both board loadwise, even though the current of the second board dosnt flow through it the current of both boards does flows through the connectors of the switch.

 

[JonAW]

[quote It can be pulled as incorrect if the front end switch is physically too small to accept both cores comfortably (appropriate crimps may be needed) also the submains must be marked up with regards to supplying two dist' boards in this manner.
Another point is the rating of the looped switch must be able to withstand the current of both board loadwise, even though the current of the second board dosnt flow through it the current of both boards does flows through the connectors of the switch. ][/quote]

I agree with this also. Using 16mm tails the mains switch should be able to accomodate the loop ok. If the mains switches are rated at 100A then there will be no problem carrying the load of the 16mm cables as with the length of cable factored in there is no way your tails should be carrying 100A.