This seems impossible- wiring of light/switch?

I am evaluating some old wiring in my home (1940's) which has armored cable wiring. I have a light switch which has only two wires (black/white cloth covered) entering the box. When I remove the light fixture, there are there are three sets of wires in the box: two sets that are three-wire and one that is two-wire.

When I try to determine continuity by twisting the two wires in the box together and touching the probes of a tester to the wires in the light fixture box with the ohms set on 1X (or any scale actually), I do not get a reading?

Shouldn't the pair of wires in the box both go directly to the loght fixture?

Thanks,
Bill

 

You may find the pair of wires coming from the switch are traveller wires to and from the switch. You will have to figure out what the other wires control to start with. If you test the two three wire cables for power one will most likely be energized and the other will not if this is the case then the two neutrals of the three wires are connected together and go to the fixture, the blacks are then connected together with the white going to the switch with the black from the switch going back to the fixture. The third wire on the two cables are then connected together and placed inside the box. The white wire going to the switch should be remarked at each end with a different color so you can identify it as a traveller to a switch this will help you in the future and say you time and maybe your life as you will know it is now a hot wire.
I hope this helps