30Amp Garden Supply

[daveoz]

I need to run a supply to a garden shed to power various items including garden lights, pond pump, and swimming pool equipment, and to have a connivent place to connect lawnmower etc. My C.U. has a spare slot and a 30mA RCD.
The pool heater is required to have a 20Amp supply, the other items add up to around 8Amps. Distance to shed is approx 20 meters from C.U.
My questions are,
What size cable is needed, do I need to have the shed on a ring or just take a single feed from the C.U. Do I need to add any additional RCD protection. I was planning to run a cable from the spare RCD protected outlet on the C.U. to the shed and then connect this to a separate C.U. with build in 30mA RCD and run independent circuits to a number of power points, but have the heater connected its own separate MCB.

 

[Adam_151]

What size cable is needed

Considering just one of the circuits you want to run from the shed is a heating load of 20A, then you want a submain of at least 32A, ideally 40A or more... I wouldn't be pulling in less than 10mm² SWA

do I need to have the shed on a ring or just take a single feed from the C.U.

radial, nothing other than sockets is wired as a ring final

Do I need to add any additional RCD protection. I was planning to run a cable from the spare RCD protected outlet on the C.U.

If you do it that way, no, but I'd prefer to take it from non RCD side and either provide RCD in shed board, or use an RCBO at the house

to the shed and then connect this to a separate C.U. with build in 30mA RCD

Pointless to have two identical RCDs like this*, they won't discriminate
*unless you are looking for redundancy

and run independent circuits to a number of power points, but have the heater connected its own separate MCB.

Sounds good, are you aware of the requirements of the building regs for this work?

 

[Steve]

and see here