swa 2 circuits

[mogga]

looking for coding thoughts please guys
4core 6mm swa red connected to 6a mcb feeding lighting under big parasol
blue connected to 32a mcb feeding heater under big parasol
black connected to neutral
yellow connected to earth
SWA is glanded at db but cant assertain at load end as its built
so 2 circuits 1 neutral l iI Know this is wrong BUT what regs cover this AND cant see any way to repeir without starting again there are 5 of these units s o rewiring is out the window and using yellow as neutral as i dont think I could get into it THESE things are a PIT%A
ALSO they seem to be able to be lowered with power still on creating fire risk

 

[AndyL]

314.4 and 521.8.2 both talk about final circuits being seperate i.e not sharing neutrals coded as C2 according to GN3

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[topquark]

No immediate danger from the combined loading. Reg is the one to do with matching live conductor sizings (book's in the van and it's pi**ing down, I'll go grab it if it stops). If there's an RCCB both circuits must be on it already. I'd go with a C2 from that respect. Debateable whether the fire risk should make it a C1 I guess.

Any chance of converting these five to 40A dist circuits and installing an suitably IP rated lockable external DB to supply the heater and lights? That would just leave you the external wiring to tidy up a bit, may be a little easier. I assume that the SWA CCC for derating for burial etc is OK.

Edit: The reg I was thinking of is 524.2.1 The neutral conductor, if any, shall have a cross-sectional area not less than that of the line conductor.

 

[mogga]

Thats the baby Quark thanks as for converting and fitting external db penny pinchers wont have it Im disconnecting them anyways as the heater thingys 1300w each 4 per parasol are fed by a nonstandard plug and 0.75mm 3 core flex protected by ---------------------------------------------------------------------------------------------------------------------------------------------------YIP that nasty 32a MCB not even an RCD in sight
Id rather inconvienence a couple of numptys who want to sit out in cold and eat than fry them just so they can stay warm

 

[AndyL]

1300w each 4 per parasol are fed by a nonstandard plug and 0.75mm 3 core flex

Ahhh, so thats why all the snow melted so quickly in the beer garden:cheesy:

 

[Engineer54]

Thats the baby Quark thanks as for converting and fitting external db penny pinchers wont have it Im disconnecting them anyways as the heater thingys 1300w each 4 per parasol are fed by a nonstandard plug and 0.75mm 3 core flex protected by ---------------------------------------------------------------------------------------------------------------------------------------------------YIP that nasty 32a MCB not even an RCD in sight
Id rather inconvienence a couple of numptys who want to sit out in cold and eat than fry them just so they can stay warm

Unfortunately you don't have the authority to arbitrarily lawfully disconnect anything, without the owners consent!! You can only advise your clients and/or issue a danger notice or whatever you call them these day's if they don't want them disconnected.....

 

[topquark]

If they're that tight, what about running the lights from the same circuit as the heaters (heaters gonna use around 22A) and fusing down for the lights with an external fused switch (say one of the lewdens or equiv). That would mean having the light switches outside though which is by no means ideal. Other alternative would be utilise wireless switching off the one circuit (again fused down), you'd only need the one controller (so may be cheaper than the DB route).

 

[GaryM]

Edit: The reg I was thinking of is 524.2.1 The neutral conductor, if any, shall have a cross-sectional area not less than that of the line conductor.

A contradiction to 431.2.1, second paragraph!
Which basically says the OPD should match that of the current carrying capacity of the neutral if it's CSA is less than that of the line.

 

[topquark]

A contradiction to 431.2.1, second paragraph!
Which basically says the OPD should match that of the current carrying capacity of the neutral if it's CSA is less than that of the line.

Although not explicitly stated, I think you'll find that's in reference to three phase supply, where the neutral may be smaller. See 524.2.3.

 

[GaryM]

I'll have a look when I get home whilst I eat my well deserved pizza!

 

[londonlec]

Would this comply if the cable was a 5 core, two neutrals, two lives and an earth? Im intregued to know!

 

[telectrix]

Would this comply if the cable was a 5 core, two neutrals, two lives and an earth? Im intregued to know!

i would say yes, as long as OCPDs were correctly rated, but stand to be corrected on , as i'm not 100% sure.

 

[Richard Burns]

Would this comply if the cable was a 5 core, two neutrals, two lives and an earth? Im intregued to know!

The two circuits line and neutral would be OK but you would have to check that the CSA of the CPC was suitable for the maximum demand placed on it which could come from both circuits.

 

[telectrix]

even so, it's highly unlikely that you will get simultaneous earth faults on both circuits.

 

[GaryM]

The two circuits line and neutral would be OK but you would have to check that the CSA of the CPC was suitable for the maximum demand placed on it which could come from both circuits.

It would be compliant with 543.1.2(ii) via 543.1.4 and table 54.7.