G
Gloster Boy
Hi, (new to forum, first thread)
Trying to get my head round voltage drop and using the calcs in practice.
I have radial circuit - 16 amp MCB on a 30mA RCD - 2.5 flat T+E out of household consumer unit, straight through wall and running in plastic conduit along outside of wall and into garage - 12 meter run.
I want to put a shed up top of the garden another twenty meters away. Using junction box can I extend the existing circuit using 4mm SWA from the junction box to the shed?
The circuit would consist of one single 13 amp socket in garage with fused spur for fluorescent strip light, double 13amp socket in shed, with fused spur for another strip light and two 50 watt lamps on the outside of shed.
design current i've calculated = 13.73 amps
So can I split the calculation in two
i.e.
v drop for 2.5mm part of run : 18 x 13.73 x 12m
----------------- = 2.97 v
1000
+ v drop for extension : 11 x 13.73 x 20m
---------------- = 3.02 v
1000
therefore, 2.97 + 3.02 = 5.99 v
5.99 v drop would comply with regs.
Is this a correct way of calculating this circuit voltage drop? And if it is, is this a safe and compliant installation? I'm sure that better practice would be to run the whole thing in 4mm SWA but SWA isnt cheap.
Or am I completely missing the point?
Sorry to those who may be asleep by now, any responses would be greatly appreciated.
Cheers
Trying to get my head round voltage drop and using the calcs in practice.
I have radial circuit - 16 amp MCB on a 30mA RCD - 2.5 flat T+E out of household consumer unit, straight through wall and running in plastic conduit along outside of wall and into garage - 12 meter run.
I want to put a shed up top of the garden another twenty meters away. Using junction box can I extend the existing circuit using 4mm SWA from the junction box to the shed?
The circuit would consist of one single 13 amp socket in garage with fused spur for fluorescent strip light, double 13amp socket in shed, with fused spur for another strip light and two 50 watt lamps on the outside of shed.
design current i've calculated = 13.73 amps
So can I split the calculation in two
i.e.
v drop for 2.5mm part of run : 18 x 13.73 x 12m
----------------- = 2.97 v
1000
+ v drop for extension : 11 x 13.73 x 20m
---------------- = 3.02 v
1000
therefore, 2.97 + 3.02 = 5.99 v
5.99 v drop would comply with regs.
Is this a correct way of calculating this circuit voltage drop? And if it is, is this a safe and compliant installation? I'm sure that better practice would be to run the whole thing in 4mm SWA but SWA isnt cheap.
Or am I completely missing the point?
Sorry to those who may be asleep by now, any responses would be greatly appreciated.
Cheers