Shed wiring
- Thread starter kmb27560
- Start date
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OK. In that case, as I said, 10mm² SWA will be more than adequate for your present requirements and also incorporates a appreciable degree of 'future proofing'. However,as I hinted before, if there is the slightest possibility that you might ever have greater load requirements (more than 32A / ~7.4 kW power) in the future, it might be worth thinking about 16mm - since even a 40m trench is mighty hard work to dig, if you're doing it manually (in answer to your previous question, a minimum of about 450mm deep).
Kind Regards, John
I think you're right with the 16mm being the best for the future John, and yes I will be digging the trench by hand. Although going down to half a metre might make me reconsider.
I am looking at installing ground source heating in the near future, so I may well combine the two jobs and rent a digger.
The other thing that I was thinking of with the 16mm is how the heavier cable attaches to a domestic consumer unit. Is there enough room for a cable that size?
I am looking at installing ground source heating in the near future, so I may well combine the two jobs and rent a digger.
The other thing that I was thinking of with the 16mm is how the heavier cable attaches to a domestic consumer unit. Is there enough room for a cable that size?
Now we are down to 40m, under normal circumstances I would say that 10mm² cable (allowing you up to around 32A power) would probably be adequate future proofing. However, given the size of your shed, I suppose there are possibilities that 'unusual' larger loads may arise in the future. The marginal difference in cost of 10mm² and 16mm² cable is not enormous, so it might be the way to go.
I wouldn't personally even think of attempting to terminate 16mm² SWA (or, frankly, SWA of any size) directly into a consumer unit, particularly a 'flimsy' plastic one. Far better to terminate it in some sort of box/enclosure close to the CU and take T+E cable (or singles) from there into the CU.
Kind Regards, John
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Given the short length of cable concerned, voltage drop is not really an issue, so current-carrying capacity is the only issue. On that basis, if it's being run from a 32A MCB or RCBO, then 4mm² (maybe 6mm²) would theoretically be OK. However, it is arguably 'nicer' to stick to the same cable size as the SWA, not the least in case someone decides that more power is required in the future and 'upgrades' the 32A RCB/MCBO for something larger.
I presume that the supply to the shed will be protected by an RCD or RCBO.
Kind Regards, John
Don't really want to go around the houses but, with definitions being a little ambiguous. If we calculate VD from Main CU, why would we not calculate it from sub-main or beyond.
The likely reason the discussion has arisen so often(must have missed them), as it seems ambiguous and clarification is needed.
FFS.
So - basically you have no idea how to relate cable size and MCB rating and loading, and you have no desire whatsoever to learn, do you?
You just want people here to do your job for you.
GO AWAY.
Personally i would just strip the tails longer and pass the tails through the box uncut to the CU terminals.
Obviously if a metal box run an earth to the metal box from the CU earth terminal
Blimey - that's quite a reaction! Have I found the customer relations department?
I didn't know the cable size to use - that's why I asked.
I do have a desire to learn - that's why I asked.
Thankfully John has been very helpful and pointed me in the right direction.
I didn't know the cable size to use - that's why I asked.
I do have a desire to learn - that's why I asked.
Thankfully John has been very helpful and pointed me in the right direction.
That's what I assumed (a 32A MCB or RCBO in the house consuimer unit) - does anything I said appeare to be incompatible with that?
If you're using an MCB in the house CU, will that circuit be RCD protected?
Kind Regards,
Yes, that would be fine, although, if it's 16mm² SWA,some might want to avoid the hassle of manipulating 16mm² conductors within the CU (and terminating them in an MCB) by using something smaller than 16mm² from box to CU (give or take my caveats). There would obviously also have to be a connection from the SWA armour to an appropriate 'earthing' place (CU/MET).
Kind Regards, John
Don't take it personally - it's an ever-present part of the forum's customer relations dept which most of us have encountered and learned to live with! In fact, if you can grit your teeth and see past the bolier-plate responses and rudeness, he is (believe it or not!) generally very well intentioned and he does have a lot to offer.
Kind Regards, John
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