What you need to know BEFORE you change your wall switch

What you need to know BEFORE you change your wall switch

Back in April, I wrote a blog about something people new to Z-Wave (or home remodeling in general) didn’t realize: Your old home was not built with smart switches in mind. 

You can read my entry here:  http://www.zwaveproducts.com/learn/blog/which-switch-is-which

As well as the top FAQ’s here: http://www.zwaveproducts.com/learn/ask-an-expert/faq

Retrofitting your electric is still a point of confusion for some, and device that was a popular workaround for the past 5 years is no longer as available as it used to be. I figured I’d take another stab at this, both for your installs, or at least be knowledgeable talking to your electrician.

Many wall switch installations in older electrical systems (pre-1980's in the US) only have a hot wire coming in from the fixture (load) box, and another going back to the fixture itself (plus some type of ground). The switch ‘breaks the leg’ of the hot wire, thus interrupting the circuit.

Many, if not most, of the Z-wave devices available today require a neutral wire as well as the hot. Think of them as mini-computers. Your computer plugs into the wall with 2 prongs (maybe a 3rd as ground) and smart Z-Wave wall switches are no different.

I drew up two diagrams on what it means to not have a neutral in the box (I omitted any ground wires to avoid confusion, and to save myself a few brush strokes).

In the drawing above, the major difference with the wiring is where the power comes from. In order to save a few bucks, wiring was run to the load, and only the hot “leg” was run through the wall switch box. Sometimes there is even a neutral behind the box for the wall switch, but it just bypasses the box itself. This process changed as homeowners (and safety codes) evolved over time. Just keep in mind that houses get remodeled over the years. 10 electricians will do things 9 different ways, and that doesn’t account for 50 years of DIY before you started making your home smarter. Know what wires are by testing them. Consult a licensed electrician for help.

So, what to do if you don’t have a neutral in the box?

You have a few options:

  1. Consult an electrician to rewire the switch. Yes, this is a kick in the teeth, considering all the claims of ‘no rewiring needed’. But marketing can’t take all situations and environments into account. You may be better off throwing new electrical updates into your next remodel, including better service, safety, convenience, and the possibility to extend the limits of your smart home further than what you could do otherwise.
  2. Install a 2-wire dimmer. The workaround for incandescent bulbs in the past was to have a dimmer that never completely turned off. There was always a tiny bit of electricity slipping past the dimmer, which, combined with the physics of alternating current, supplied a false neutral. The problem began when LEDs came down both price and load.  The LEDs were not drawing enough power. That little trickle of energy was sufficient to power the LEDs at a noticeable level, even if the dimmer was at its lowest setting. Two ways around this are to forgo changing your bulbs to LEDs, and leave the incandescent bulbs installed. Alternately you can have an electrician install a dummy load to increase the draw down to where the LEDs would be less noticeable.  The con with this? The dwindling supply of 2-wire dimmers. The conditions that require this arguably have been outdated for the past 15-20 years. GE had cornered the market with their 2-wire dimmer, but that is no longer readily available to us.  But there is hope with this product: Leviton VR106-1LZ. Just don’t use it with LEDs. 
  3. As long as your load is under 2.5 amps (roughly 300 watts) you should consider the Aeon Labs Micro Smart Dimmer. This fits anywhere you have a box, including the possibility of installing it where your load is (since the load requires both a hot and neutral). This device also benefits you when you have a custom device color and all we have is boring white. It also works with 3, 4 and 5 way setups.
Who would have thought that the majority of issues DIY folks have with their smart home install have little or nothing to do with the protocols or automation? I hope this article helped.
Previous article Unhacked. Safety and Security with Z-Wave
Next article A Z-Wave Horror Show?