NICEIC assessment

[Tnse7]

Hi guys new to this forum. Looking to my NICEIC assessment so I want to make sure I get this job completely correct. Doing this work for a friend to use as my assessment piece.

He wants a power and lighting circuit to his garden shed 40m away from the house, around a 50m run in total from the consumer unit, he wants to put a lighting and power circuit in there, but also has plans to at some point turn it in to more of a summer house.

The swa will be clipped direct around then house then buried in a trench under the patio and along the base of his garden fence, I had planned to bury the swa 600mm deep in sand with a cable marker above this, would this need to go in ducting?

This will then enter the shed and terminate in the consumer unit in the shed, then run in singles in plastic conduit in the final circuits.

Due to the length of run and to future proof I thought a 10mm 3 core SWA, using one of the cores as cpc from a 40a breaker would be enough to ensure staying within the maximum ZS for that breaker?

Any thoughts/tips welcome or anything I've missed or completely got wrong please let me know

 

[Murdoch]

The most important thing about running sub mains is to define the maximum design load on your quote. If you do not do this you may open up a nasty can of worms later ......... and by the way you've written you post have you considered the load and resulting volt drop and the maximum permissible volt drop on lighting circuits? 

 

[boltonsparky]

Also what supply type is it, I've heard of assessors pulling people for not rodding outbuildings if it's on PME, potential can of worms and I'm not making judgement on whether that's right or wrong just what I've heard other people say.

 

[Tnse7]

@Murdoch I did check the volt drop quickly using the megger calcs app and it came in at 2.3% which is under the permitted 3% for lighting

@boltonsparky I had heard of that too, it is a tncs system so might be worthwhile just installing an earth rod to to stop any problems during assessment

 

[Murdoch]

@Murdoch I did check the volt drop quickly using the megger calcs app and it came in at 2.3% which is under the permitted 3% for lighting

What did you enter as your KW load? because 50 meters is one hell of a run with 40A load ..........

 

[Tnse7]

I used 6kw, I cant see him having any more equipment in there than that, that even allowed for a couple 2kw heaters if he wanted

 

[Murdoch]

In which case I would fit a 32A Mcb on the submain - to prevent the load becoming the issue down the line. 

 

[Tnse7]

@Murdoch thanks for the advice I will definitely do that actually

 

[Murdoch]

@Murdoch thanks for the advice I will definitely do that actually

Make sure that the maximum design load is 32A on your quote / estimate ......... 

 

[binky]

@boltonsparky I had heard of that too, it is a tncs system so might be worthwhile just installing an earth rod to to stop any problems during assessment

It is illegal to export earthing from the equipotential zone (ie house) without permission from DNO. So rod it at shed end. Don't forget armour still needs earthing (house end) which also means as you aren't taking an earth you could use 2 core SWA. SWA is also OK to direct bury in the ground.

 

[Tnse7]

@binky  Thanks binky, great shout on the 2 core, save the customer a bit of money. Yep was going to earth the swa from house end and terminate in a double pole switch in plastic casing shed end. Then tails up into the small consumer unit. Thanks for all the friendly advice guys 

 

[Andy™]

@binky  Thanks binky, great shout on the 2 core, save the customer a bit of money.

no idea why some insist on using a core as a cpc when the armour is adequate. sometimes has its advantages but for the best part it doesnt

 

[Sidewinder]

I had a guy in a wholesaler once (big national chain with more than one brand) that 2 core was illegal & I had to use 3 core...

I wanted several km of the stuff for one site, so there was no way I was going to 3 core!

 

[Andy™]

I had a guy in a wholesaler once (big national chain with more than one brand) that 2 core was illegal & I had to use 3 core...

I wanted several km of the stuff for one site, so there was no way I was going to 3 core!

hope you took your business elsewhere then. cant remember the last time i bought any 3 core, i only buy 2 or 4 core

 

[Bruspark]

Only thing I'd add is don't bury it too close to the fence posts.     

Firstly they will then blow over more easily due to the disturbed soil/sand and the fence guys who come to brace or replace them (probably at your expense) will then stick their drill/spade through the cable to completely make your day . .  

For extra points predict the stance of all concerned over who should pay for what . . .