Right cable for Shed?

Tandey

Have a 3x4 stranded cable running out from a shed(not connected to the fuseboard yet) its a good 30/40metre run in a pipe buried under the ground(has been there for a while but not damaged).
Its going to a barn where there are 3 waterproof sockets and a 16amp 230v socket for a welder but also for 3 fluorescent lights in same barn, im pretty sure its not possible to put lights and those sockets all on that cable, shouldn't the cable be 4 core at least or is this possible with that 3x4?

forureyesonly

You need to calculate how mush power the shed will use at any one time, add up the total Kilowatt ratings of everything that will be used at any one time in the shed (its unlikey everything will be going at the same time). when you find out these figures there is a volt drop formula to use to determine if your cable will be ok to use.
As for the fluorescent lights, the control gear associated with them can sometimes trip the rcd which can be a pain in d a**, however i have seen it done loads of times, by using a switched/fused spur taken of a socket. A way around this problem is installing a sub board in the shed itself where you can split the circiuts, but it is the more costly option.

Bruthal

30 to 40 meter run is a fair run for a 3x4 cable, might just about get 20 amp load on it, but its very tight for the voltage drop allowed.

And its from one shed to another? Then the first shed would also have a volt drop on its supply cable.

And you can put all different items on a cable by using a sub board in the shed being suppled as previous poster suggested.
But the cable has to be big enough for what you are using.

Tandey

Yes sub board is not really an option here as the person wants it done as cheap as possible but safe at the same time, would be a big job getting another cable across the yard so have to stick with the 3x4, but only one socket will be ever used at a time and one flourescent at most will be on together with an appliance in the socket at one time, its not ideal but just the way it is with this.
So for the lights use a fused/switched spur then bring power to the switch for the lights from that spur.

Tandey

robbie7730 wrote: »

30 to 40 meter run is a fair run for a 3x4 cable, might just about get 20 amp load on it, but its very tight for the voltage drop allowed.

And its from one shed to another? Then the first shed would also have a volt drop on its supply cable.

And you can put all different items on a cable by using a sub board in the shed being suppled as previous poster suggested.
But the cable has to be big enough for what you are using.

Yeah sub board in other shed, its a bit dodgey putting sockets and then also lights on that one cable without putting a sub board in the second shed, what should be used for the cable back at the board?(apprentice btw)

Bruthal

Tandey wrote: »

Yes sub board is not really an option here as the person wants it done as cheap as possible but safe at the same time, would be a big job getting another cable across the yard so have to stick with the 3x4, but only one socket will be ever used at a time and one flourescent at most will be on together with an appliance in the socket at one time, its not ideal but just the way it is with this.
So for the lights use a fused/switched spur then bring power to the switch for the lights from that spur.

yes should work grand like that. put 3 or 5 amp fuse into the spur for the lights and should be grand.

Bruthal

Tandey wrote: »

Yeah sub board in other shed, its a bit dodgey putting sockets and then also lights on that one cable without putting a sub board in the second shed, what should be used for the cable back at the board?(apprentice btw)

If your going to run the cable straight into socket in shed then the circuit
needs to be RCD protected. A 20Amp RCBO would do the job, But as i was saying, 30-40 meters of 4 square conected from a shed already fed by another cable might have a bit too much volt drop unless the load is kept small.

Tandey

robbie7730 wrote: »

If your going to run the cable straight into socket in shed then the circuit
needs to be RCD protected. A 20Amp RCBO would do the job, But as i was saying, 30-40 meters of 4 square conected from a shed already fed by another cable might have a bit too much volt drop unless the load is kept small.

Yeah its a fair distance to have much a load on that size cable, 20Amp RCBO Type C maybe because of the surge if a welder is being used or would Type B be grand for it?

Bruthal

Tandey wrote: »

Yeah its a fair distance to have much a load on that size cable, 20Amp RCBO Type C maybe because of the surge if a welder is being used or would Type B be grand for it?

Id say it would need a type c alright,

ntpm

Tandey wrote: »

Have a 3x4 stranded cable running out from a shed(not connected to the fuseboard yet) its a good 30/40metre run in a pipe buried under the ground(has been there for a while but not damaged).
Its going to a barn where there are 3 waterproof sockets and a 16amp 230v socket for a welder but also for 3 fluorescent lights in same barn, im pretty sure its not possible to put lights and those sockets all on that cable, shouldn't the cable be 4 core at least or is this possible with that 3x4?

I would strongly recomend a sub board.
You should have individual breakers as this will reduce nuisance tripping and is better on safety grounds. Also the welder may cause a normal breaker to trip due to surge Amperage.
Therfore a small enclosure and the following breakers would not be too costly:
Mainfuse Switch
10A MCB Lights
63A RCD supplying:
20A MCB Sockets
20A MCB (C rated) Welder.

Bruthal

ntpm wrote: »

I would strongly recomend a sub board.
You should have individual breakers as this will reduce nuisance tripping and is better on safety grounds. Also the welder may cause a normal breaker to trip due to surge Amperage.
Therfore a small enclosure and the following breakers would not be too costly:
Mainfuse Switch
10A MCB Lights
63A RCD supplying:
20A MCB Sockets
20A MCB (C rated) Welder.

Yea id tend to agree, if people say they want it done cheap then id just not do it unless they are doing it properly.

Tandey

ntpm wrote: »

I would strongly recomend a sub board.
You should have individual breakers as this will reduce nuisance tripping and is better on safety grounds. Also the welder may cause a normal breaker to trip due to surge Amperage.
Therfore a small enclosure and the following breakers would not be too costly:
Mainfuse Switch
10A MCB Lights
63A RCD supplying:
20A MCB Sockets
20A MCB (C rated) Welder.

robbie7730 wrote: »

Yea id tend to agree, if people say they want it done cheap then id just not do it unless they are doing it properly.

Yeah will offer to do it properly or not do it at all, best method of not having anything fall back on you if something goes wrong, thanks for all that advice lads.

Bruthal

Tandey wrote: »

Yeah will offer to do it properly or not do it at all, best method of not having anything fall back on you if something goes wrong, thanks for all that advice lads.

If you did use a sub board then the cable will just need a 20amp c type mcb on the board its being fed from.

Tandey

robbie7730 wrote: »

If you did use a sub board then the cable will just need a 20amp mcb on the board its being fed from.

+1 sound out, was really confused as what to do before got your advice thanks a million

Bruthal

Tandey wrote: »

+1 sound out, was really confused as what to do before got your advice thanks a million

No bother.

M cebee

cable is undersized for welding anyhow over that distance


- coming off another shed