Diversity factor

No diversity should be applied to lighting in my view. It  is reasonable to suppose that every light will be turned on if the office is used during the hours of darkness.

I would in fact add a small margin for manufacturing tolerances and and mains voltage variations. If the calculated load is say 60 amps, then allow for 66 amps. Add 5% for manufacturing tolerances and another 5% for mains voltage variations.


For general purpose small power circuits, a lot of diversity can usually be applied to the circuit ratings, 50 circuits each of 20 amps does not normally mean 1,000 amps in total.

If however the load to be supplied is specified or calculated in watts per square meter, then in my view this presumably includes diversity. (the exact loads are unknown and wont all draw the maximum power at the same time) If the specification states say 40 watts per square meter , then in my view it means 40 watts per square meter, and not some lower figure.


Such estimates work well as an average for LARGE office areas, provided that a reasonable figure of average watts per square meter is allowed.

For small offices it can end very badly. Consider an office five meters by five meters, an area of 25 square meters . At say 40 watts a square meter for general purpose power, that is only 1,000 wats. What if someone uses a 3Kw kettle, or a large vaccuum cleaner or a power tool ?


For 100 such offices, a total of 100 KW might be reasonable, they wont all use kettles or power tools at the same time ! but for a single small office no way.


A good approach for small offices in my view is to allow for the actual connected load for lighting, and say 40 watts per square meter for general purpose small power, plus 3KW, no matter how small be the office.


How many watts per square meter to allow calls for engineering judgement and experience.

I

No diversity should be applied to lighting in my view. It  is reasonable to suppose that every light will be turned on if the office is used during the hours of darkness.

I would in fact add a small margin for manufacturing tolerances and and mains voltage variations. If the calculated load is say 60 amps, then allow for 66 amps. Add 5% for manufacturing tolerances and another 5% for mains voltage variations.


For general purpose small power circuits, a lot of diversity can usually be applied to the circuit ratings, 50 circuits each of 20 amps does not normally mean 1,000 amps in total.

If however the load to be supplied is specified or calculated in watts per square meter, then in my view this presumably includes diversity. (the exact loads are unknown and wont all draw the maximum power at the same time) If the specification states say 40 watts per square meter , then in my view it means 40 watts per square meter, and not some lower figure.


Such estimates work well as an average for LARGE office areas, provided that a reasonable figure of average watts per square meter is allowed.

For small offices it can end very badly. Consider an office five meters by five meters, an area of 25 square meters . At say 40 watts a square meter for general purpose power, that is only 1,000 wats. What if someone uses a 3Kw kettle, or a large vaccuum cleaner or a power tool ?


For 100 such offices, a total of 100 KW might be reasonable, they wont all use kettles or power tools at the same time ! but for a single small office no way.


A good approach for small offices in my view is to allow for the actual connected load for lighting, and say 40 watts per square meter for general purpose small power, plus 3KW, no matter how small be the office.


How many watts per square meter to allow calls for engineering judgement and experience.

I