(30-12-2010, 10:52 PM)Archie Wrote: Hi, would someone be so kind to tell me, within a LOC on 'new works' why we use the pink 1.0mm wire for points relays, and not the standard 0.75mm white, it is obviously a bigger cross section, is it a case of less resistance, if so why is this significant. There is probably a very simple answer to this I am not sure of, but I was working in Reading over Christmas doing 'changeovers' and been back on the NLL today doing Mods for the testers, and it has come into my brain on the way home as a question to ask.
Many thanks
You are right that the larger wire size is used so that the resistance is lower- not really a matter of current carrying capacity as such but lowest possible voltdrop is important.
The difference in size may not seem a lot but remember that the ratio of the cross sectional area is approx 2:1. It is used for the points drive circuits and thus just for the wiring from the busbar to the outgoing cable terminations via the points contactors. The outer diameter of the two wires are actually very similar, which is why pink insulation has been selected for the larger wire is used, so that the two can be readily distinguished.
PJW