2 posts / 0 new
Last post
Old Wiring

Greetings- I have a 1930's home that I'm sure has been updated over the years, but I'm trying to figure out this wiring.  When I pull a light switch out of the wall, in some cases I see only two wires and in some, 3- which is for 3-way switches.  My question is- how do I determine hot from neutral and in the case with 3-way, hot from "traveler" as both/all are wrapped in the same colored, cloth sheath?  This of course is the same throughout the house with ceiling fixtures, electrical outlets, etc.  Everything is in a cloth sheath with no inidicator of hot and neutral.

Re: Old Wiring


You cannot replace any of the switch devices with new devices, other than single pole switches and the outlets. A single pole does not matter, it merely breaks the circuit. Most of the time, the power comes into the fixture. The 3-way circuits are not wired the same as they are today. You have knob-and-tube wiring circuits in your house. There are still only 2 wires with all knob-and-tube circuits, and no real neutral as you now know it. Any cable that is cloth covered is only an update to the care conductors of the knob-and-tube conductors. I will bet they are connected to the knob-and-tube circuits to merely extend the circuit. They will not carry a large load for todays circuits.

Even with circuits of today, don't trust the color of the jacket. Meter out the circuit to make sure that it is wired the way you believe. Current does not know color.

It is much easier if you replace all the knob-and-tube with better wiring. I have re-wired many old homes, including my own and helped my dad when he purchased the Victorian house that I grew up in. That way in the 60's and things were different then than they are now. My parents house had a 40 amp service, and that fed 4 floors in the house. My house had a 60 amp service that also fed 4 floors in this house. I replaced all of that and now we have 800 amp service in this house. I used MC cable in my house. Mice and squirrels will not chew on armor cable, but they will chew on romex.


Handy Andy In Mt Airy NC

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.