Hi,
I'm at the final stage of my coursework and there is a few things which I'm trying to clarify i.e.
100m2 is the total area of the rural-premises.
I've used a 1-phase TN-C-S (TT was recommended but the choice of earthing system is not that important).
My main lighting circuit has 160m total length, and the volt drop using following formula for 1.5mm2 conductor size is:
Vdrop = (Ib x mv/A/m x L)/1000
Vdrop = (5.6 x 29 x 160)/1000 = 26 or 11%
According to Appendix 12 table 12A the maximum allowable vdrop on lighting ccts is 3% (6.9V) therefore do I have to use 4mm2 conductor size in order to meet the regulations or my formula is wrong ?
The second part is diversity:
12kW cooker, Ib = 61A.
Ib after diversity = 37A (60%) In = 40A <- this values has been used in Ipsc calculations.
As I look at the "Electrical installation design guide" it tells me to use diversity on cooker cct at the design stage so I can use lower rating of MCB.
So I'm just wondering, should I not use the worst case scenario i.e. 61A or is 37A legally acceptable ?
The final Ib has to be =< 100A (suppliers limit), mu current Ib currently is 180A(including Ib for cooker after diversity) so I can use any diversity factors to fit within the limit or could you recommend some real-life formula for it ?
Thanks in advance,
Tom
I'm at the final stage of my coursework and there is a few things which I'm trying to clarify i.e.
100m2 is the total area of the rural-premises.
I've used a 1-phase TN-C-S (TT was recommended but the choice of earthing system is not that important).
My main lighting circuit has 160m total length, and the volt drop using following formula for 1.5mm2 conductor size is:
Vdrop = (Ib x mv/A/m x L)/1000
Vdrop = (5.6 x 29 x 160)/1000 = 26 or 11%
According to Appendix 12 table 12A the maximum allowable vdrop on lighting ccts is 3% (6.9V) therefore do I have to use 4mm2 conductor size in order to meet the regulations or my formula is wrong ?
The second part is diversity:
12kW cooker, Ib = 61A.
Ib after diversity = 37A (60%) In = 40A <- this values has been used in Ipsc calculations.
As I look at the "Electrical installation design guide" it tells me to use diversity on cooker cct at the design stage so I can use lower rating of MCB.
So I'm just wondering, should I not use the worst case scenario i.e. 61A or is 37A legally acceptable ?
The final Ib has to be =< 100A (suppliers limit), mu current Ib currently is 180A(including Ib for cooker after diversity) so I can use any diversity factors to fit within the limit or could you recommend some real-life formula for it ?
Thanks in advance,
Tom