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Mike, Master Electrician
Category: Electrical
Satisfied Customers: 1425
Experience:  Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
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I have a multi tester if I need to use it. I was swapping

Customer Question

Hello, I have a multi tester if I need to use it. I was swapping out some old and loud 3 way light switches in my 1908 built home. The wires are all black and there is no ground. Here is the configuration: two switches in one box operate two lights, one upstairs and one downstairs, (top and bottom of a staircase). Upstairs its the same configuration. I made the mistake of swapping the switches without checking or marking wires. The downstairs switches were newer and worked fine. When I got upstairs, the switches were different, the screws all faced me and they did not match the layout of the modern, Leviton 3 way switches. I put the old upstairs switches back in after realizing I goofed it up. For instance, they would only operate when one switch downstairs was toggled up or down, and did not work as designed. I replaced the upstairs switches with the old ones and one side works fine and the other side only works from downstairs to operate the downstairs light on and off when the upstairs light switch is toggled in the down position. DO I need to test all wires and find the common? Do I need to do this only upstairs? How do I test the wires with a multi tester to check for the hot wire? Does a hot wire trgo one per switch? For example, in my case I have 4 switches will there be a common, hot wire for each switch? three wires per switch with one hot and two travelers? I will let you answer now and you can ask me more since this is kind of confusing. In my mind, I would take the upstairs switches out, test for the hot lead, mark them, and then connect the new switches accordingly. I learned after the fact about common leads and traveler wires but now I don't know which is which?
Submitted: 9 months ago.
Category: Electrical
Expert:  ProGrade replied 9 months ago.

Welcome to

Would it be possible for you to take a picture or two of the wiring and upload to the sight?

It is very possible but not likely that all wires are black. Could you try wiping them off or gently scraping the insulation to see if a different color comes thru? Thanks

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