what size armoured cable

[peteludman]

you woud have to use 25mm 3 core or 35 mm if you was going to use armour as cpc

and VD for lighting is 3% but you are not putting the cable in to supply only lighting its feeding a submain from the DB(submain) thats when you want to worrie about 3% volt drop feeding lights.

 

[Guest123]

VD is calculated from the origin of an installation in this case the house so you must include the sub-main as part of the lighting circuit.


Quote from ECA...

Answer by the ECA: The overall voltage drop limit is 3% (6.9V) single-phase, if the sub-main is feeding lighting circuits.

 

[MarcT]

and VD for lighting is 3% but you are not putting the cable in to supply only lighting its feeding a submain from the DB(submain) thats when you want to worrie about 3% volt drop feeding lights.


The only trouble is that you still need to satisfy Sec. 525 whichever way you approach the matter

 

[peteludman]

VD is calculated from the origin of an installation in this case the house so you must include the sub-main as part of the lighting circuit.


Quote from ECA...

Answer by the ECA: The overall voltage drop limit is 3% (6.9V) single-phase, if the sub-main is feeding lighting circuits.

ok thanks mate you learn every day is tha the same for comercial

 

[Dic Penderyn]

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[FONT=&quot]Despite bringing the design current down, and using 3% as stipulated by the ECA the length of cable run will invariably be a 25mm cable with regards to Voltage drop. [/FONT]

 

[MarcT]

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[FONT=&quot]Despite bringing the design current down, and using 3% as stipulated by the ECA the length of cable run will invariably be a 25mm cable with regards to Voltage drop. [/FONT]

You are quite right, the end result is the same. The great thing about this forum is that it encourages debate (albeit sometimes polemical). Lenny, quite rightly challenged my calculation, and i justified it in this case.

All designs are case specific and sometimes there are no wrong answers due to the ambiguity of the regs.
I think opinions are good. The worst thing is not have one

 

[Guest123]

We cant base anything much on assumptions...the OP doesn't even know what loading he will have.

I maintain that as the submain will be supplying lighting circuits in the garage, the max VD is 3%.

 

[sparks1234]

Perhaps the original 11Kwatt maybe a little over the top.
Must be one hell of a garage door to be 2 Kwatt.
Lights and power 4Kwatt?....what is being run?

 

[wattsup]

I originally guessed the load required...2kw is a reasonable assumption for average up and over garage doors if single phase, but of course for only a short period.
Lights and power, again an assumption. But if you install sockets you have to assume max load could be applied, electric kettle? water heater? you get the idea.....Lighting, maybe a 500 watt sunflood lighting up the 90 metre walk...
I would think 11kw was a distinct possibility. I don't know what the regs say regards diversity for small outbuildings I would assume max demand when in use, hence 25mm.
I could however be persuaded to use 16mm, but it would be on a 45a breaker, the vd is the problem in this case and the potential load.

 

[pennywise]

Think you may be over egging the garage door motor power consumption the biggest ones i've ever seen on a domestic is 400W for a 230v one and 190W for a 24V. Though every situation is different cheers