Garage Supply , 80 Metre Run

[Dal Roberts]

Have a job garage supply 80 metres, demand no more than 4kws, but calculated 6kw 26 amps for future proofing and calculated 9.18 volt drop which is ok and below 5% or 11.5 volts on single phase 230v and maximum length on 10mm S.W.A , there is a spare gang in the house consumer, and calculations show 32a mcb to be ok. would any of you sparky veterans recommend a different approach, any advice would be appreciated 

100 metres maximum length calculated

 

[ProDave]

Try 3% volt drop for lighting  (I assume there will be a light in the garage)

 

[Murdoch]

How are you going to stop a trip in the garage affecting the house?

 

[Dal Roberts]

6.08V volt drop at 4kw Pro Dave but not 6KW 9.18V umm 

How are you going to stop a trip in the garage affecting the house?

Hi Murdoch what would you recommend 

 

[Murdoch]

6.08V volt drop at 4kw Pro Dave but not 6KW 9.18V umm 

Hi Murdoch what would you recommend 

It would depend on the CU in place.......

 

[Dal Roberts]

its a split load RCD protected 

 

[brman]

Try 3% volt drop for lighting  (I assume there will be a light in the garage)

or you could select the lighting to meet the voltage drop

eg. min supply = 217V, 9V drop giving 208V which is above the minimum voltage for a lot of electronic ballasts to start.

(eg 198V for these http://www.nationallampsandcomponents.co.uk/en/pdf/tridonict8_1.pdf)

In someones shed would you really go above 10mm2 swa just to get within 3% drop for lights, particularly as, in reality, it will probably be getting above 230V even at full load?

 

[Murdoch]

its a split load RCD protected 

do you mean a dual RCD? (17th) 

or

RCD and MCBs? (16th)

 

[Dal Roberts]

technically they would only be using 2.5kw, 10.8 amps in the coldest winter , so 4.4 m/V/am x10.8 amps x80metres = 3.80 volts drop

 

[brman]

I'd be more worried about getting it on its own RCD/RCBO (but preferably with DP switching...) than the voltage drop. Unless the customer says a potential slight dimming of lights is going to be an issue?

 

[Dal Roberts]

do you mean a dual RCD? (17th) 

or

RCD and MCBs? (16th)

Split Load CTI (new make I've never seen em) 2x ZR80 80a RCCBs either side of spilt load murdoch

 

[Murdoch]

Split Load CTI (new make I've never seen em) 2x ZR80 80a RCCBs either side of spilt load murdoch

can you post a picture?

 

[brman]

is this what you are talking about?

http://www.harbordelectrical.co.uk/consumer-unit-18ways-17ed.html

what wylex and co call a high integrity?

 

[Blue Duck]

rebeanded BG board Murdy, probably 17th.

@op you either need a mcb or rcbo at the house end and an rcd board at the shed end.

what are earthing arrangements?

 

[Dal Roberts]

TN- S Blue Duck 

is this what you are talking about?

http://www.harbordelectrical.co.uk/consumer-unit-18ways-17ed.html

what wylex and co call a high integrity?

Thats the one 

 

[Murdoch]

TN- S Blue Duck 

Thats the one 

If that is the one its your lucky day as you can use the non RCD section to put a MCB in and then you can have a RCD board at the other end.

Why ANYONE fits standard dual boards is beyond me. I fit Hi Int or RCBO's in houses these days. IMHO dual boards should be banned!

 

[brman]

If that is the one its your lucky day as you can use the non RCD section to put a MCB in and then you can have a RCD board at the other end.

Why ANYONE fits standard dual boards is beyond me. I fit Hi Int or RCBO's in houses these days. IMHO dual boards should be banned!

Probably because they save 50p and they don't have the extra neutral running around internally getting in the way of your speghetti wiring

I agree with you, I always fit either all RCBO or hi integrity.

 

[Dal Roberts]

If that is the one its your lucky day as you can use the non RCD section to put a MCB in and then you can have a RCD board at the other end.

Why ANYONE fits standard dual boards is beyond me. I fit Hi Int or RCBO's in houses these days. IMHO dual boards should be banne

this particular one is fitted with 2 80A RCDS and 2 busbars i presume, i haven't taken the lid off yet , so how would i arrange for an independent new 32A MCB from the busbar for the 80 metre run ?

 

[apprentice87]

What about calcs for Zs????

Whether the customer minds if the lighting dims a bit does not matter, the install either complies with the regs, or it does not.. YOU have to sign that it does [including volt drop], and part p applies too...

john...

 

[Dal Roberts]

What about calcs for Zs????

Whether the customer minds if the lighting dims a bit does not matter, the install either complies with the regs, or it does not.. YOU have to sign that it does [including volt drop], and part p applies too...

john...

Yes John , worked out 80 metres of 10mm at 1.83 m ohms / metre , equates to 0.15 ohms