Adding in-wall z-wave switch to house with old wiring


(Kleinbaum) #1

Help! I’m trying to add a the monoprice dual relay module to two light switches in my house. Of course, my house was built in 1926, which means nothing here is ever easy.

Here’s my problem: I opened up the outlets, and the wiring doesn’t make much sense to me.

Outlet one (far right, first photo below) has three wires - a red and black at the bottom, and white at the top.This is a 3-way switch - there’s another switch that controls these lights. From what I’ve read, these relay modules can be installed on some 3-way switches, so I wanted to try it here.

Outlet two (middle of three outlets in photos, second photo below) only has two wires: A black and a white. And the white is coming from outlet 1, not the wall, which really confuses me.

Right now, here’s my best guess: Black wire is live, white wire the load (and these two switches share a load - not sure if that’s actually possible), and red wire goes to the other switch for the 3-way. And these are just old enough that there is no ground.

Does this make sense? Any other explanations? Is it possible to use the monoprice relay without a ground, or am I screwed?

thanks, Josh


(Don) #2

I am not an electrician by any means. If I understand your description and question correctly. I would make this assumption as to how the 2nd switch is wired. The (hot) live wire is connected to one side of your light in the overhead. You then have another black wire coming from the the other side of light to the switch. The other side of the switch is connected to common (white) which is also common on the other switch. The switch is in line of the live lead so when you flip it, the circuit opens and stops current flow.

This could all be verified with a non contact voltage checker along the circuit path.

You’ll probably have to get inside the lights wiring to be 100% sure.

Just my opinion. Hope that helps.


#3

As @tn_oldman says, don’t guess. You need to check every segment to make sure you know exactly what it’s doing. If you don’t know how to do that, bring in an electrician.

US code does not mandate wire color so people can and do use any color for anything, especially if it’s getting towards the end of the day and you only have one spool left in the toolbox.


(Don) #4

Couldn’t agree more on professional help if stumped. I do industrial maintenance for a living. When I get confused with house wiring I call in my cheap (free ) professionals. Both my sons are union electricians.


(David S) #5

Based on your description of what you see and your understanding of it, I think it would be wise to consult a professional to help with this.

With respect to the 3 way circuit, it takes a fairly good understanding of it to be successful in migrating to the GE zwave switches as they require you to adjust the wiring and in some cases, add more. In short, your three way switch will have the same switch and wiring for both switches. You must replace one switch with a full GE switch and the other with an add on. Both of your current switches will be identical, but one is for line and the other is load, and they are connected to each other on the two wire side.

To be successful, you have to determine which of the switches is line and which is load. You’ll probably have to cap the load and send it back to the line switch…


(Joe) #6

I have the same issue as you and i’m sorry to say that the only way to truly fix this is to run new wire. I tried everything to get around it and researched for ever and there really is no other way.