3Ph sub-mains supplied via 5-core NYY, not SWA. OK or not?

[Mark42]

Good morning
I need to fit a new 3 phase dis board in an annexe I'm building at my own house.
Usually I'd use SWA, or singles in conduit/trunking, but as the run is all in loft space and not liable to physical damage (no rodents), I'm thinking of using surface-clipped 5-core 16mm NYY instead, especially as there are some tight-ish turns, and space in the board it's coming from is also tight.
I can think of no technical reason why this is not OK. Possibly it's routine?
Any comments?
Cheers
Mark

 

[telectrix]

this seems to agree with you:
NYY - Protected Cables - https://www.tlc-direct.co.uk/Main_Index/Cable_Index/NYY/index.html?ad_position=%7badposition%7d&source=msn&ad_id=%7bcreative%7d&kw=www.tlc-direct.co.uk%2fMain_Index%2fCable_Index%2f&matchtype=b&ad_type=%7badtype%7d&qry=NYY-J%20cable&campaign=dynamicsearchads&msclkid=6c55c34893d2178ddf49982ca7077640

 

[Spoon]

Is this new CU an addition to the existing house CU?
Why 16mm?

 

[telectrix]

Is this new CU an addition to the existing house CU?
Why 16mm?

maybe it's a cannabis farm extension.

 

[suffolkspark]

id go with nyyj aswell

 

[Mark42]

Is this new CU an addition to the existing house CU?
Why 16mm?

Because NYY's not easy to find in 25mm

New self-build extension which is eventually for holiday rental (It's my retirement fund!)
Fed from the main DB which is 100A x 3 in 25mm.
There's no reason not to allow for future expansion in the annexe (ie do it once!) and I want to add a Tesla charger 3 x 16A or 3 x 32A to encourage the right kind of rental client

 

[Spoon]

Because NYY's not easy to find in 25mm

Eland do 5 core 25mm... Link A9N525

 

[suffolkspark]

The only thing i would say is check if its stranded..... I got some 6mm nyyj on a job recently and it was solid core!

 

[Midwest]

Would this be in Malaysia or UK?

 

[Rockingit]

4c 25mm HO7 and a 16mm GY would have been my first look.
NYY I think is always solid core.

 

[rapparee]

4c 25mm HO7 and a 16mm GY would have been my first look.
NYY I think is always solid core.

I was thinking h07rn as well, but why not 5 core?

 

[Rockingit]

I was thinking h07rn as well, but why not 5 core?

4c + G/Y is just cheaper and also if he's got some tight turns then it's more flexible /sharper radius too. Also makes it easier (smaller) to gland into a panel if space is tight.

 

[rapparee]

4c + G/Y is just cheaper and also if he's got some tight turns then it's more flexible /sharper radius too. Also makes it easier (smaller) to gland into a panel if space is tight.

Yeah, it'd take a 50mm stuffing gland for 5 core. I'm using a lot of it recently.

 

[Mark42]

Would this be in Malaysia or UK?

UK

 

[Mark42]

Thanks for the ideas.
BTW, I was joking about 25mm as I thought another poster was implying 16 was too big for a small annexe! It is only a 10m run, and will have a 32 or 40A TP MCB.
I hadn't considered H07RN. If as SuffolkSpark says, 16mm NYY might be solid (really?!) that's no good. I'm going to order 1m to check.
The thing is, although I know rubber flex is totally fine, both from a technical and regulation perspective, I can easily imagine a future inspecting electrician saying that some cowboy has used FLEX (!) for a sub main rather than SWA, like you 'have to'. Can anyone here say that could never happen?
At least NYY looks like SWA.

 

[Rockingit]

The only thing you'd need to do to HO7RN would be to put crimps on the terminations as it's fine stranded, other than that, fill yer boots man. Idiots will always walk among us, we can't see into the future except to use common sense today. Besides, I've lost count of the number of submains run in 16mm t+e through all kinds of spaces where it could be argued something else would have been better. If you're only running 32-40A then I'd suggest 10mm 5c HO7 is plenty overkill.

 

[Rockingit]

here's a datasheet for you......

 

[rapparee]

The only thing you'd need to do to HO7RN would be to put crimps on the terminations as it's fine stranded, other than that, fill yer boots man. Idiots will always walk among us, we can't see into the future except to use common sense today. Besides, I've lost count of the number of submains run in 16mm t+e through all kinds of spaces where it could be argued something else would have been better. If you're only running 32-40A then I'd suggest 10mm 5c HO7 is plenty overkill.

Your preaching to the converted.

I did a job in SWA last year, 35mm 5 core 160A supply, I had fitters and toolmaker conscripted in to help me pull it in.

I vowed from then, that ho7 would be my new cable of choice, I think it is actually more robust than SWA, especially in the bigger sizes.

 

[Mark42]

Although the spec for 16mm NYY states 'solid core' I was right to not believe it. A sample arrived today. 16mm, at least, is definitely stranded, strips really easily, and looks easy to work with.




So I'm going to go with the NYY at £6.77/m rather than H07RN which is £10.17/m.
Many thanks for all the helpful advice.

 

[Wilko]

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