Negative Wire
 

I am trying to install some home automation stuff, came to a switch that had a white wire in the box connected to one side of the switch.

Is there a way that I can find out if it is a negative wire?

Thanks

I'm assuming by "negative" you mean neutral. Take a voltmeter and measure AC volts from the white wire to the ground (bare) wire. You should read zero volts, although a reading of 1-2 volts isn't uncommon.

Are you installing X-10 or ???

David,

Thanks, I don't have a voltmeter, just one that tells me if I have 110 or 220.

I am using Insteon, love it.

Nice to see another home automation person here! I've been using X-10 for, jeeze, over 20 years. I've actually got several Insteon keypads and a few switches, but I use an Ocelot for my macro duties, so it's all X-10 based at the moment. I've been kinda busy the past couple of years (divorced, moved, re-married, etc.) so I haven't been playing with it much. Fun stuff. Amazing how used you get to it. I've got wake up, bedtime, arrive, depart, etc. for sequences. "What, turn all the lights off or dim by HAND? Are you crazy?"

A good digital volt meter is as cheap as a pair of Channel locks these days.
The white wire is typically neutral. Like David says may be a volt or 2 to the green ground wire.
Harbor Freight around $5 for a small digital meter. Sears maybe $15 or $20.

Why, WHY did I read this thread? Why, WHY did I google 'home automation'. I sense another very expensive hobby starting.....

Heh-heh-heh... HAWDP (Home Automation World Domination Plot).

Harddrive, check out smarthome.com, they have some cool starter kits. Plus they have a nice sale on at this time.