Just a quick one on SWA size to out building

[timo]

Guy asked for a quote for a main feed taking to an out building at far end of garden.

The ou building will be supplying ring main, lights, etc. Also he would like to take feeds from this to a green house and a potting shed to supply sockets and lights.

Im allowing 60A for Design current to the out building
The distance is 80M give or take a few inch

I've had a look and 35mm SAW needed would you agree this would be more than enough for the above.

Also i've only gone upto 25mm so far whats 35mm like to work with . What Switch Fuse and whats best to terminate it at the out building with.

Cheers in advance

 

[GrannySmiff]

crikey is that not very excessive?.

 

[johnboy6083]

35mm2 easy enough to work with,as long as you allow yourself space. a trick though, if its cold when your working, try and gland/terminate the cableas soon as you can after pulling it in, as it gets cold, it will get harder to work with.

 

[nickblake]

25 mm would be more than adequate for design current and voltage drop use a 3 core 25mm swa voltage drop is 0.67 and current handling is 82amps using method D

 

[JUD]

25 mm would be more than adequate for design current and voltage drop use a 3 core 25mm swa voltage drop is 0.67 and current handling is 82amps using method D

It looks like you've used the three-phase reactive voltage drop value to work that out (the column under x in table 4D4B three-phase section). You want the column under z in single-phase.

Voltage drop for 80m of 25mm² 70°C SWA single phase at 60A would be 8.4V.

1.75 x 80 x 60 ÷ 1000 = 8.4

This is too high for his lighting circuits.

@timo.....What is the outbuilding going to be used for. Are you sure 60A isn't going a bit OTT?

 

[nickblake]

do you know just some times ,jud your right my appologies error on my behalf new i shouldnt have gone to specsavers

 

[JUD]

No worries. We all have our off days

Just to pour a bit of salt on the wound, you've done the same with the Current Capacity. It's actually 99A for single-phase

Sorry....couldn't resist

 

[nickblake]

LOL you swine ,been working on three phase for days im off to specsaver tomorrow lol

 

[timo]

It looks like you've used the three-phase reactive voltage drop value to work that out (the column under x in table 4D4B three-phase section). You want the column under z in single-phase.

Voltage drop for 80m of 25mm² 70°C SWA single phase at 60A would be 8.4V.

1.75 x 80 x 60 ÷ 1000 = 8.4

This is too high for his lighting circuits.

@timo.....What is the outbuilding going to be used for. Are you sure 60A isn't going a bit OTT?

LOL @ spec savers

Yeah well i did the same and with the lighting points that where i came up with needing 35mm.

@JUD
At the mo the requirments would be:
Outbuilding (2 story garage at mo that will be converted to a gym/storage are) i can see min 2 rings needed and 2 lighting circuits.
Also front this building a supply to quite a few garden lights (70watt par38's)
Then a feed front this to a green house
Also a feed to a potting shed
More things may be added later on also as things are on going at the mo.

 

[timo]

Bump...

Whats best gear to get to terminate guys?

 

[timo]

Anyone?

 

[johnboy6083]

if you mean glands, then you would be better using CW type glands than BW. CW clands are far superior, and give a better purchase on the cable. From memory, i think its a 25CW that you will need.

Also, form your cable before inserting the gland into your CU. if you dont, then when you try and make the cable look good, then you will damage the CU.

 

[laney06]

This may be of some help. Remember, it guidance only though.

Cable Size Selector Calculator and online cable selector for electricians

Howard.