Metal Electrical Boxes


(Rodimus) #1

I live in Chicago and by code all electrical needs to use metal electrical boxes to house switches and plugs. Would the metal box block the signals transmitted by the z-wave and zigbee switches?

I am actually interested in converting my existing switches by purchasing the micro switches offered by Aeon Labs.


(Florian Z) #2

FWIW, the Aeon Micro Switch has an external antenna. It’s a short (about 4 inches) wire. Maybe you can position these in your gang box so that the antenna wire can stick out into the wall?


(Tim Slagle) #3

I live in Chicago as well. No problem here with any of the switches I have setup:)


(Rodimus) #4

Thanks for the info! I’m relieved to hear that they still transmit. I’ll probably try positioning the antenna to slip through the gang box just in case.


(Jake) #5

Fellow Chicagoan (suburbs). I have no issues with switches in metal gang boxes sending or receiving signals (even across large spans).


(Im Brian) #6

I have metal gang boxes and have converted most of my switches to Jasco without issue.


(Chrisb) #7

As others have said, I have a many switches in metal boxes along with heavy plaster walls… the only issue I’ve had is some of the devices that are the farthest distance from my hub wouldn’t initially setup when the hub/device needed to be in direct communication. Once I moved the hub, paired the device, then moved the hub back to it’s normal home everything was fine.


(John Roberts) #8

I think I have proven WITHOUT A DOUBT metal boxes do in fact shield Z-Wave signals. I have within the last hour completed a very exhaustive problem solving session in this regard.

All of the electrical boxes in my house and my outbuildings are metal. My experience has been you can just about forget about pairing a device in a metal box unless the switch is facing in the direction of the hub or very close to the hub. I have gone so far as to run ethernet lines near the device and move the Hub in the near proximity in order to pair. Trouble is, once you pair the device you must then return the HUB to its usual position, and the connection is not reliable. You will continue to have networking/routing errors and intermittent operation. I do not buy into this idea that once paired the devices will operate at longer ranges. That is not been my experience at all.

Another technique I have tried is leaving the device extended out of the metal box during the pairing operation. I have demonstrated this on numerous installations where this will work until you place the device back into the metal box. Then inconsistent and unreliable operations began. Often Network repairing will ​show no errors, yet the devices will not operate and there are no exceptions on the devices in the phone app.

I have tried using repeaters to overcome the signal loss. I have yet to find one that solves this problem. Seems the shielding is very effective.

Now here is what I have found that does solve the problem. If you have a metal box with removable sides (these are boxes that are “gangable”), remove the exposed side. Move your device to that position if it is ganged. This way you have one side of the Smart Switch completely exposed and not shielded. This was the only method I found that would work in my barn and shop. Will it meet code? Perhaps not; but it does work. It will correct problems with other devices that might be in the same gang box.

Hope this helps someone… It has driven me to the point to where I want to tear all of these things out and send them to the trash Heap. Seems things are operating dependably​ now with these modifications.


#9

Zwave switches in metal gang boxes

Zwave signals are Omnidirectional (360 degrees) so as you noted, you can catch the signal in just one direction as long as you have another device to do so. And of course you want to avoid a metal faceplate since then you’ve closed off all four sides.

OK, so you’ve got a Z wave radio inside a metal box with a plastic face plate. Now you have to get signal through the plastic, that’s the critical point. So you need another mains powered Z wave device (not battery powered, those don’t repeat) within about 40 feet (you can go longer if it’s a zwave plus device) where the signal can get directly to the plastic faceplate. It could be a Z wave bulb on the ceiling, it could be a pocket socket on the opposite wall, maybe even a pocket socket in the next room over. (Pocket-sockets have the advantage that they themselves are not trapped in a metal box.)

Also be aware that when you have metal gang boxes, that means you have a lot of metal inside your walls, even if those aren’t networked devices. So there could be dead spots as the signal tries to go through walls as well.

So most of the time if you’re having trouble with signal to zwave light switches in metal boxes, the following should help:

One) choose Z wave plus over classic zwave if you have a choice. You’ll get much better range.

Two) choose a plastic face plate for the switch. Not ceramic, not metal.

Three) put a Z wave plus pocket socket within 75 feet of the light switch so that the signal could go directly to the faceplate. ( it’s OK if the line is through a wall, but then the range will be reduced somewhat.)

One pocket socket can repeat signal to all of the switches in a room although it will be least successful with the ones on the same wall that it is on, because then there won’t be a direct line through the plastic.

Pairing Range

There are many different factors that go into pairing range, which is why there’s so much confusion about this.

First, the easiest. If you have zwave plus light switches, as long as the switch is within one hop of a repeater, you can pair it in place. So, easy.

If it’s a Z wave classic light switch, however, it has to be within one hop of the hub or a minimote at the time of initial pairing or it can’t join the network. For light switch, you can install it where you want it and then bring the hub to the switch, or bring a minimote to the switch.

Z wave locks have still yet different pairing rules, as they must be paired within “whisper distance” in order to exchange a security key with the hub. But that doesn’t apply to light switches.

After you have all the devices where you want them to be, it’s a good idea to run a Z wave repair just to make sure that all the neighbor tables are up-to-date.

OK, what all this means is once the switch has been paired to the network and the neighbor tables are up-to-date, you get much longer range because the switch can pass messages to other mains powered Z wave devices like a relay race and that’s what extends the total distance that your devices can be from the hub. Each device still has the same signal strength and sends a message for the same number of feet. The difference is just that that message can be picked up by a device other than the hub and passed along until it eventually reaches the hub.

I definitely would stick with code requirements, but as long as you’re willing to put a pocket socket in the right place and use plastic faceplates you should be fine even with a metal gang box. :sunglasses: