Hi .. after endless hours of research on the web i feel its led me to too many different answers so now i am asking for advice from competent and proper tradespersons ... i have built a block built workshop 20ftx16ft aprox 30 metres from my house which i plan to run a few power tools I:E table saws, grinder.. the normal workshop type stuff . installing also 4 x 2 gang sockets for tv, a chest freezer etc and also 2xflourescent ceiling lights .. i have brought 35 metres of 10mm 3-core swa and have recently had a full rewire of the house done and the kind gent left a 40A breaker in the main CU for me to run my outdoor electrics from ... Can i just bury the swa underground (a spade depth) or should i bury some kind of conduit and thread the swa through, do i only run the swa upto the house and have it connected to a outdoor socket and the have some twin n earth from socket to CU or would the swa have to be connected directly into the main CU inside the house and also directly into the CU in the workshop, also what type of CU should i get to put in the workshop .. i am askin this as i want to do as much work myself as i can beforehand to save installations costs and then get a competent part p sparks in to go over what i have done and sign off for me. Please forgive if anything sounds a bit "stupid" but i am not a sparks
The SWA is fine for direct burial, a duct would be a top end pro way to go. Possibly consider a duct for Ethernet/phone/alarm? Consider water also? You want to dig once! The cable would be best taken directly back to the mains and glanded off into the main CU, or via an adaptable box sat below or close to the main CU. Fit a metal clad CU in the workshop, and gland the cable directly into it. Omit RCD protection at house, place it in the new CU in workshop. You can export the PME earth to workshop, main protective bonding to any extraneous parts in the workshop.
what kind of CU could be reccomended for the workshop .. would a CU with a 63A , 16A , 6A be sufficient for power tools, lighting, sockets .. also to route the 10mm swa i have to Bend the cable coming out of the workshop and go underground ( a spades depth) into the house wall at just above floor level run the cable through some trunking Behind kitchen cabinets and behind an electric cooker through a small wall that the main CU is on. also i have about 50mtr of blue 25mm water pipe could i bury that and just pull the swa through for extra mechanical protection when its buried, i am weary of the blue pipe because of temperature factors of the blue pipe and the air flow around the swa inside the blue pipe .. ALSO should i go straight into the 40A breaker in my main CU OR should i put it in its own CU in the house and run that CU to the main CU ... should i allow for voltage drop because of the distance of the run of cable (30mtr) .. and also should i allow for bending radii
Most of the tools you've listed are what I'd call 'flicker' causers. You turn them on and the lights dim for a bit. They pull quite a load on start up.If you're using 10mm SWA, go for a 40A or 50A MCB in your house, not on an RCD. The main switch in your outhouse DB would probably be a 63A/30ma RCD. Doesn't matter it's larger than the MCB in the house. And you put your cable in twin wall ducting, not blue water pipe. For a 30m run probably 50/63mm size for 10mm cable. It comes with a pull cord, which you'd pull blue polypropylene cord through first, then attach the cable to that.
ok getting the idea now lol ... so do not need an indoor rcd as it could get connected directly to the already in place unused 40A mcb in the main CU .. and get a 63A, 30A, 6A CU for the workshop ... as for the twin ducting .. is this neccesary or am i just being over protective of the buried swa ... i know someone with a similar set up and he has an extra 80A isolater in his workshop .
You can bury the SWA direct if you want. I feel it's better in ducting. Plus if you leave a drawstring in you can pull through other cable at a later date. You won't manage to push 10mm SWA through 30m of 25mm blue pipe. Not without wishing you'd used twinwall ducting and a pull cord, at anyrate.
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