Design Question

[rolyberkin]

Designing a new build installation at the moment and am looking to run 2 X swa sub mains from the incoming supply to small consumer units in a workshop and double garage. What is the preferrable way to connect these cables. I was considering via a fused dp switch unit or via two ways in consumer unit? All cables will be buried. Has anyone got any photos of similar installations?

 

[telectrix]

you can split the tails into henleys and 2 KMFs. then into adaptable box for each so you can gland your SWA cables. better than coming from a MCB in the main CU as that would only give S/P isolation.

 

[hightower]

Tel is there not something about one point of isolation for the installation? Could be wrong and a million miles away, just interested in this thread too for learning

 

[telectrix]

you're right. ideally, a 2 pole isolator should come after the meter to isolate all DBs as 1 installation, if you regard an individual installation as being anything after the meter. some might say that each DB is a separate installation. all comes down to interpretation of the regs.

 

[rolyberkin]

you're right. ideally, a 2 pole isolator should come after the meter to isolate all DBs as 1 installation, if you regard an individual installation as being anything after the meter. some might say that each DB is a separate installation. all comes down to interpretation of the regs.

What about the supply tails from meter to DP isolator, then henley block to three sets of feeds, two to fused DP switches then connecting to adaptable boxes and swa, third set to house consumer unit. I think this would need to all go in the house as the DNO surely wouldn't be happy with all that in their supply box?

 

[telectrix]

sounds good. but all depends on what space you have to fit all the gear. meter boxes are not known for having enough room to fit much in.

 

[Leesparkykent]

personally I don't like Henley blocks on a new installation. what's the design current of each distribution circuit?

 

[rolyberkin]

Looking at 40amp RCD's on the garage and the shed/workshop. Both will be low use power and lights, the swa cable to the workshop is a 16mm 3 core SWA as it is a fair way from the house and I wanted to future proof it as he is already talking about also building a BBQ lodge near by which will need power and lights. Realistically the usage on both will be the occasional power tool and some LED outside lights .

 

[Leesparkykent]

Looking at 40amp RCD's on the garage and the shed/workshop. Both will be low use power and lights, the swa cable to the workshop is a 16mm 3 core SWA as it is a fair way from the house and I wanted to future proof it as he is already talking about also building a BBQ lodge near by which will need power and lights. Realistically the usage on both will be the occasional power tool and some LED outside lights .

I would install a high integrity board and install fuse carriers on the main switch side for the distribution circuits. http://www.hager.co.uk/product-catalogue/energy-distribution/protection-devices/fuse-carriers/hrc-fuse-carriers-bs88/38532.htm

 

[rolyberkin]

I didn't even know they existed, thanks!

 

[hightower]

Thanks too Lee - I wasn't aware either, not that I have something like this lined up but very helpful to know

 

[Leesparkykent]

I didn't even know they existed, thanks!

will be cheaper/easier than installing switch fuses and imo will look a lot neater.

 

[hightower]

will be cheaper/easier than installing switch fuses and imo will look a lot neater.

Yeah deffo, added with the fact you don't need adaptable boxes to terminate the SWA too

 

[rolyberkin]

Yeah deffo, added with the fact you don't need adaptable boxes to terminate the SWA too

Looks like just the ticket, just have to use an adaptable box the other end to negate the whole exporting of earth issue!

 

[hightower]

What's the issue?