Any electricians?

[The Wardog]

Ok so I’m starting my first grow in me shed and obviously I’ll be needing power.

 

I’ll be running a 600w hps, 2 rvk 6 inch fans, an oscillating fan and an oil heater in the colder weather. Depending on humidity I may need a dehumidifier but I’m hoping I might get away without one if I can keep my temps and airflow in check.

 

The shed is next to an existing out building which has power so my main question is, will I be safe to tap into one of the sockets from the out building and run everything I need to power from that or am I best getting an electrician In to run a dedicated power cable to the shed from the house fuse box?
 

Obviously I know the best option would be for it to have its own power but that’s going to cost more and be a hell of a lot more work. 
 

All help appreciated 

[EatonMess]

1 hour ago, The Wardog said:

Ok so I’m starting my first grow in me shed and obviously I’ll be needing power.

 

I’ll be running a 600w hps, 2 rvk 6 inch fans, an oscillating fan and an oil heater in the colder weather. Depending on humidity I may need a dehumidifier but I’m hoping I might get away without one if I can keep my temps and airflow in check.

 

The shed is next to an existing out building which has power so my main question is, will I be safe to tap into one of the sockets from the out building and run everything I need to power from that or am I best getting an electrician In to run a dedicated power cable to the shed from the house fuse box?
 

Obviously I know the best option would be for it to have its own power but that’s going to cost more and be a hell of a lot more work. 
 

All help appreciated 

What's the power rating of the heater?

If the socket you speak about in the existing out building is part of a ring final circuit then you can run ONE 2.5mm spur (unfused) from that to your shed. If it's already a spur, then you can still run a socket but it must be fused at 13A.

Assuming power ratings of around 30W ea for the RVKs and 50W for the oscillating fan - you're looking at 710W including the HPS. 

You're not wanting more than 13A draw from that socket, ever. So your absolute maximum power draw should be <~3120W.

3120W - 710W = 2410W to play with. Plenty for a decent heater and humidifier.

Is this were me, I'd run a 2.5mm cable from the outbuilding socket to a fused spur and then to a socket. Into that socket you can plug an extension lead (however many gangs you want providing the plug is fused correctly). That way you have double fused protection (switchd fused spur + fuse in your extension lead). I'd also try and keep things <10A. The less current the better really.

Remember that what limits the current draw from a socket isn't the cable, but the socket itself, specifically the cable terminals. So don't go plugging in a heavy load (tumble dryer, washing machine, etc) into the socket that you're spurring from as you'll have substantial load on the terminals that could result in a fire.

If the ring circuit you plan spurring from has RCD protection at the fuse box then that will carry through to your shed socket. If you don't have RCD's in your fuse box, you can buy metal clad sockets with RCD protection built in - about £20 for a double gang.

Edited October 24, 2019 by EatonMess

[The Wardog]

Thanks @EatonMess I think I follow all of that lol.

 

The Heater I was planning on using is 1000w so like you said I should still have plenty to play with. But how will I be able to tell if the existing socket in the out building is already from a spur or if it’s part of a final ring circuit?

 

i was planning on using sockets with RCD protection anyway just as a fail safe.

 

[botanics]

12 minutes ago, The Wardog said:

But how will I be able to tell if the existing socket in the out building is already from a spur or if it’s part of a final ring circuit?

 

If it's on the ring it'll have two sets of tails, if not, either a radial or spur.  Fuse the spur where you tap off the ring not after a previous spur   

[EatonMess]

1 hour ago, The Wardog said:

Thanks @EatonMess I think I follow all of that lol.

 

The Heater I was planning on using is 1000w so like you said I should still have plenty to play with. But how will I be able to tell if the existing socket in the out building is already from a spur or if it’s part of a final ring circuit?

 

i was planning on using sockets with RCD protection anyway just as a fail safe.

 

@botanics is bang on. Two tails i.e. two grey cables going into the box.

[The Wardog]

I’ve had a look and it’s definitely a spur so the plan is to add a fuse and socket running into the shed. 

 

 Thanks for the advice @EatonMess & @botanics. As you can tell electrics isn’t my strong point so you’ve definitely saved me a lot of time and potentially money getting an electrician out to look at it 

[EatonMess]

No problem!

If you can, keep everything in your garage metal clad and your twin and earth cable in conduit. You're wanting to get a 13A switched fused connection unit (1) along with 20mm conduit (X metres), 20mm conduit saddles (depends on length of conduit) and male conduit adapters (3). Cheap as chips.