Discuss Voltage drop on radial and ring in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
Hi,are you confused as to what the acceptable VD is,on those circuits,or how to calculate,given layout and conductor size?
assuming you are using a 20A MCB for the circuit, then Ib must be less than 20A. ( Ib<In<Iz). if you estimated load is more, then you need to redesign the circuit.
yes but you probably won't have all the lights on at the same time, so some diversity can be allowed in a domestic..... comml. and indl. may require all on simultaneously. same with socket outlets. you can never be precise in determining the IB unless you know exactly what is going to be plugged in, which is impossible.What I'm trying to work out is the lb of 5 13amp sockets, I know how to work it out in a lighting circuit say 10 lights, 10 X 100 watts / 230 = 4.34 so lb of 4.34
So just follow the rules set out in appendix 15 of BS7671 100m2 for ring final and 50m2 for radial if using a 20A CByes but you probably won't have all the lights on at the same time, so some diversity can be allowed in a domestic..... comml. and indl. may require all on simultaneously. same with socket outlets. you can never be precise in determining the IB unless you know exactly what is going to be plugged in, which is impossible.
Yes I've seen this but I'm using a 60898 breaker and that's not listedIf you have five 13A sockets then you would need to know the rating of the breaker protecting them and use that as your limiting design current.
For a ring this would be 32A, for a radial it could be from (normally) 16 to 32A.
If you look in the tables in the on site guide chapter seven, this gives standard circuits and maximum lengths of cable. In most cases volt drop is the limiting factor (see the notes at the end of the table). This shows you the maximum length of a ring final circuit and various radial circuits, normally limited by volt drop.
You are using a circuit breaker i.e a cb in the tables, wherever it states cb/RCBO this means either a circuit breaker (to BSEN60898) or an RCBO (to BSEN61009) of the type listed.Yes I've seen this but I'm using a 60898 breaker and that's not listed
Reply to Voltage drop on radial and ring in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
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