C
Capn Ahab
Right, bear with me, cos I know this might be boring for some of you, but a bit of advice from an experienced head or two would help to confirm my thinking (or throw me into a mess of confusion....)
I recently got Part P registered (elecsa) and have been doing fairly low key jobs here and there to build up my experience, adding a circuit here, changing a CU there - you know the drill. I still haven't given up the day job, as I know I'm not ready yet...
Anyway, my latest job is to run power 50m across a garden to two circuits in a shed: lighting and a radial with 3 socket outlets. Basically I want to know if it's OK to use a 16A MCB to protect the sockets? The outhouse will eventually be used for drinking and playing darts, so very unlikely to draw much current beyond the lights, maybe a mini fridge and a music system. Before that though it will be used as a makeshift workshop while the guy does his own loft extension, so will run small power tools, but again, unlikely to draw a huge amount of current.
The bit that confuses me, is that the OSG onlys talks about standard socket outlet circuits (20A radials in 2.5mm; 32A radial in 4mm; 32A rings in 2.5mm) unless specified in accordance with 314.3 in the regs, which states (as far as I can tell) that as long as requirements for overcurrent protection, isolation and switching and current carrying capacity are met, you can protect a final circuit how you see fit. Is this right or am I missing something? I'm sure I saw a post up here saying you shouldn't run sockets on a 16A radial recently, but I can't find it now, so I can't cross check it against the reg they were citing...
The installation plan is to have a 32A MCB in the CU, with 4mm 3 core SWA clipped direct to the wall running just under 50m out to a 30mA RCD in the outhouse, with the 16A MCB and the final circuit run in 2.5mm downstream of that. Since the design current is low (say 3kW load max), and 2.5mm cable is easily big enough, I'm thinking this looks OK, but I would welcome being put right by someone who knows their stuff inside out if it's not
As regards the SWA, I have also thought about using 3 core 2.5mm. Current carrying = 25A and according to my calculations (where Ib = 13.9A) VD = 10.425v which is under 5%, but pretty near the knuckle. What do you guys recommend, should I go for 2.5mm SWA or is it cutting things too fine?
Many thanks for looking.
I recently got Part P registered (elecsa) and have been doing fairly low key jobs here and there to build up my experience, adding a circuit here, changing a CU there - you know the drill. I still haven't given up the day job, as I know I'm not ready yet...
Anyway, my latest job is to run power 50m across a garden to two circuits in a shed: lighting and a radial with 3 socket outlets. Basically I want to know if it's OK to use a 16A MCB to protect the sockets? The outhouse will eventually be used for drinking and playing darts, so very unlikely to draw much current beyond the lights, maybe a mini fridge and a music system. Before that though it will be used as a makeshift workshop while the guy does his own loft extension, so will run small power tools, but again, unlikely to draw a huge amount of current.
The bit that confuses me, is that the OSG onlys talks about standard socket outlet circuits (20A radials in 2.5mm; 32A radial in 4mm; 32A rings in 2.5mm) unless specified in accordance with 314.3 in the regs, which states (as far as I can tell) that as long as requirements for overcurrent protection, isolation and switching and current carrying capacity are met, you can protect a final circuit how you see fit. Is this right or am I missing something? I'm sure I saw a post up here saying you shouldn't run sockets on a 16A radial recently, but I can't find it now, so I can't cross check it against the reg they were citing...
The installation plan is to have a 32A MCB in the CU, with 4mm 3 core SWA clipped direct to the wall running just under 50m out to a 30mA RCD in the outhouse, with the 16A MCB and the final circuit run in 2.5mm downstream of that. Since the design current is low (say 3kW load max), and 2.5mm cable is easily big enough, I'm thinking this looks OK, but I would welcome being put right by someone who knows their stuff inside out if it's not
As regards the SWA, I have also thought about using 3 core 2.5mm. Current carrying = 25A and according to my calculations (where Ib = 13.9A) VD = 10.425v which is under 5%, but pretty near the knuckle. What do you guys recommend, should I go for 2.5mm SWA or is it cutting things too fine?
Many thanks for looking.
