Continuity of 2 way lighting

[Chris Norman]

hi all, I'm struggling a bit with continuity and trying to refresh my mind before another day of training next week. Confused slightly on 2 way lighting. I've got the hang of ring finals and radials etc.

I know I need to test all points, switches and ceiling rose (not sure correct name). I link line and cpc in the db and then test between switched line And cpc or line and cpc. What do I test at the switches? Common, L1 or L2? and cpc.

Thanks
Chris

 

[telectrix]

the rose is the furthest from the CU compared to the switches, so you test at the rose. L-E and S/L -E with switches operated in both positions

 

[Richard Burns]

For two way switching when testing earth continuity using method one you are also confirming polarity and switching in the line conductor only.
You will not necessarily know if the switch is on or off or which terminal is permanent line and which is switched line.
At each switch you can test from cpc to L1 then L2, one of the measurements will give you the continuity value, the other should be open circuit if the switch is off, if the switch is on you will get two different continuity values.
At the light fitting test cpc to switched line and then operate a switch one of the measurements will give you continuity, the other should be open circuit.
Record the highest value of continuity measured as R1+R2.
A little diagram showing one possible method of two way switch wiring (there are others) with indications of the switching possibilities.

 

[Chris Norman]

Thanks for that. Great help.