diversity

[kevplumb]

not wanting to appear thick but im not a spark (names a giveaway ) but what exactly is the above and how is it applied to the job
thanks

 

[plugwash]

are you really in afghanistan? (perhaps studying british regs because there is nothing meaningfull in place where you are?)

diversity is essentially allowing for the fact that not everything is runnign at full power at once

there are diversity guidelines in the wiring regs however for domestic properties wires with what is now a typical cuircuit count the figures come out far higher than reality. (most homes in the uk are on a 60A or 100A service fuse and the diversity guidelines frequently give figures closer to 200A yet i've never heared of a 100A service fuse blowing due to overload domestically)

generally in a domestic situation you just size the incomers for the consumer units based on the service fuse and don't worry too much about diversity. In a commercial or industrical environment it all depends to a huge degree on the usage patterns of the equiment.

 

[kevplumb]

so what you mean is for all the shower curcit is rated 45a its only in use on occasion
or have i totally missed it ?

and the second bit is that where power factor comes into it ?

not trying to be clever i worked in the transformer industry for a while

 

[plugwash]

yes its a way of allowing for the fact that you won't run everything at full power at the same time (or at least you own't do it for any significan't amount of time)

lets look at a typical house with electric shower and cooker and immersion heater

shower 40A
3 rings at 32A
2 lighting cuircuits at 6A each
cooker at 32A
immersion at 15A

163A total

and many houses have more cuircuits than this (outbuilding power loft socket possiblly electric heating etc)

using the standard diversity guidelines

shower 40
3 rings 32+0.4*(64)=57.6
lighting 12*.66=7.92
10+0.3*22+5=21.6 (note that diversity may have already been applied when specifying the cuircuit so be carefull here)
immersion 15
142.12A total
which is still way over 100A

in a household situation blowing a 100A service fuse is extremely rare though so something does seem rather out of whack with the diversity guidelines

in a larger installation you have to look at how equipment is/will be used and base your maximum demand calcualtions on that. (things are further compilcated here by phase balanceing and seperation requirements)

 

[kevplumb]

cheers m8
give me a shout if you break your boiler
most helpful and informative