Intermidiate switching combinations

[RJP1]

Hi I was wondering if someone would be able to tell me or explaine how many combinations an intermidiate switch has when it come to r1+r2 testing, I know a 2 way lighting circuit is 6 but I can't remember about intermidiate circuits.
any help would be appreciated thanks

 

[Richard Burns]

Seems like 8.
However the intermediate switch position will (should) not change the reading for R1+R2 if you have done all the options for the end switches.
Also note that when the light would be on all the line conductors are covered for insulation testing

 

[stevethesparks]

Always a good and detailed answer from Mr Burns

 

[Lucien Nunes]

I know a 2 way lighting circuit is 6

Not sure what you mean here, there are only 4 combinations of switch positions, 2²=4. For three two position switches 2³=8 but as Richard says the intermediates don't disconnect anything so don't remove any conductors from the test regardless of their positions.

Also note that when the light would be on all the line conductors are covered for insulation testing

I think this needs qualification. If the switches are wired with the PL and SL paralleled to the L1 & L2 strappers, then when the light is on all conductors are live and get tested in a single test. OTOH if the PL and SL go to the commons of the two switches (as you might do when wiring in singles) then when the light is on, one strapper is floating and does not get tested until both 2-ways are flipped over to the other on position.