volt drop query

[zone77]

When doing a volt drop calc for a sub board, is the max volt drop 5%(11.5v) ( the sub board feeds lighting and power circuits) or is it reduced to 3% (6.9v)

 

[GrannySmiff]

Does it not matter if its for public or commercial use, or am I confused?.

Just looked in BRB and it says

Public lighting 3% other 5%

Private 6% other 8%

Ah and just reading your post agian I see your point I would go with 5%.

 

[Guest123]

If the sub-main is feeding lighting circuits, the the max VD from the origin to the end of the lighting circuit fed from the sub-main DB is 3%.

 

[zone77]

i am confused now

 

[Guest123]

VD is calculated from the origin of an installation in this case the house so you must include the sub-main as part of the lighting circuit.


This is from the ECA.....

Answer by the ECA: The overall voltage drop limit is 3% (6.9V) single-phase, if the sub-main is feeding lighting circuits.

 

[zone77]

sorry should of mentioned the installation is in a pub

 

[scotsparky]

Zone 77 it dosnt matter where it is. f its from the public supply thw max volt drop from Origin is
lighting 3%
power 5%

When its designed you will find distribution cables may be oversizes so less volt drop so it can be allowed for on the final circuits.