120v relay mounting with 12v input

[oldchachie]

id like to switch a load using an ELK 912 relay with 12v dc signal and a 120vac switched load. My problem is ive always understood that one needs to separate 120v from low voltage. So some questions:
1. Using a 912, could i just put this in a regular single gang box, run the 120 and low voltage wirea in and hook them up, from an nec perspective?
2 is there a special type of box for this?
3. Is there something else id have to do to use a confiuration like this?
4. Does anyone know of a relay that can be mounted in a single or doublw gang box that has a built in divider for the high and low voltage?
Im really looking for awnsers on how to do this from an nec perspective.

 

[Sandpiper]

The NEC has a provsion for situations lke this. You can use a regular single gang box. There is a requirement in the NEC to keep the 12V wires at least 1/4" away from the 120VAC wires, so use different holes for these. [NEC 725.136(D)].

 

[BraveSirRobbin]

I would highly suggest looking into the "relay in a box" (RIB) products and not use the Elk 912 in this application.

 

[gatchel]

I would highly suggest looking into the "relay in a box" (RIB) products for your application and not use the Elk 912 in this application.

+1.

 

[Steve]

+2

 

[tmbrown97]

For legality the RIB is the easiest... but it's totally doable either way. I kinda did the opposite in the link in my sig about UPB control of my fireplace; I had to combine LV/HV in a single gang box so I took several steps to ensure the wires were well separated from each other. Not the cleanest aesthetically, but it's been working great for a year now and nothing has blown up.

That said they do make plenty of the automotive style relays for which you can get a base plug w/wires and everything is nicely separated... if you look inside industrial type equipment or even in the control box of your washer and dryer, you'll see that hi/low voltage is in close proximity all the time - you just have to do it safely to prevent a short, use the proper type of wire with adequate high-voltage insulation, etc.

 

[Sandpiper]

Anyone want to elaborate why the RIB is recommended. I see it it as this:

Elk 912 advantages - fits in a single gang box
disadvantages- care must be taken not to exceed box volume allowance per NEC 314.16, but this will not be a problem if there are no switches or outlets installed in the same box.
Care must be taken not to allow the connections or the backplane solder points to touch anything.

RIB advantages- simple pigtail connections, exceeding box volume allowances probably not an issue if mounted external of the outlet box.
disadvantage- will not fit inside the outlet box, so the outlet box must be removed and modified in order to connect this. Maybe it fits in a double or triple gang box, but if not, future access to it for maintenance is in jeopardy, and box volume allowances could be an issue.

 

[video321]

Sandpiper-
The only advantage I can see for the RiB is if the box also has something mounted to it - like a switch. As you said, how would you fit a relay in there while not exceeding the volume and push all the wires back in while keeping clearance. Then again, if you can mount the RiB somewhere then you could mount a new dedicated j-box too unless there are space issues.

 

[ddennerline]

I spent dozen of hours trying to track down an answer to this question. Forums.mikeholt.com has a bunch of confusing posts like this one - http://forums.mikeho...t=111722&page=2. I talked to my electrician about setup. He indicated that; all wiring insulation inside gang box must meet 600v requirement; 12/120v wires must be properly separated.

I have read that ALC switches provide heat shrink that is added.

Because the attic was too hot to install a Z-Wave switch, I opted to install a RiB and wrap 12v wire in 600v heat shrink tubing for controlling my attic fan.

You should probably double check with AHJ; they may require a permit.

 

[Sandpiper]

The 1/4" separation is not necessary if the heat shrink is used on each conductor.

 

[apostolakisl]

The 1/4" separation is not necessary if the heat shrink is used on each conductor.

That is good info. Does all of the heat shrink tubing you pick up at Fry's or whatever qualify or is there some specific kind? I don't recall seeing anything written on my heat shrink stuff. Can you bundle a bunch of LV wires into one shrink tube? If you do that and then you split them out at the end, do they allow some amount of tail without the extra insulation? Like if you are feeding a terminal strip on an 8 relay board.

 

[Sandpiper]

I'm not aware of any specific requirements for the "non-conductive sleeve". NEC article 725.136(D) applies to situations when you have low voltage (Class 2 or 3 power-limited) conductors in the same enclosure with 120VAC conductors when they are associated systems (devices which by design expect a mix of low and hi voltage connections, like a relay). It stipulates that the conductors must be separated by 1/4" or by a "non-conductive sleeve". I believe most jurisdictions would consider heat shrink tubing as "non-conductive".

As long as you have 1/4" separation or a non-conductive sleeve on the individual conductor where there is less than 1/4" separation you should be OK.

 

[Del91574]

Anyone want to elaborate why the RIB is recommended. I see it it as this:
Elk 912 advantages - fits in a single gang box
disadvantages- care must be taken not to exceed box volume allowance per NEC 314.16, but this will not be a problem if there are no switches or outlets installed in the same box.
Care must be taken not to allow the connections or the backplane solder points to touch anything.
RIB advantages- simple pigtail connections, exceeding box volume allowances probably not an issue if mounted external of the outlet box.
disadvantage- will not fit inside the outlet box, so the outlet box must be removed and modified in order to connect this. Maybe it fits in a double or triple gang box, but if not, future access to it for maintenance is in jeopardy, and box volume allowances could be an issue.

The big thing is they're very commonly found and stocked, economical and for the majority of applications, a handful of PN's can solve almost any input/output requirements. We use them by the 100's for the controls side of the business.

RIB's are very flexible in what they can do and input voltage range/type and switching load vs. a LV relay like a 912, which for all intents and purposes, is a 1 trick pony. The major issue with a 912 you touched on, barring the usage of snap track, which would necessitate a larger enclosure than a gang box, having a relay/board floating in a box, then factor in a couple of years, heating of the wiring, etc. drying out the double stick pads....not a pretty scene. I'd prefer to mount them via a knockout any day.

RIB's are very easy to install (barring a handy box) an maintain separation for code purposes when HV rated cabling isn't run for signalling purposes.

 

[archstenton]

Dug up this thread, some of you guys have me a little worried now trying to use a M1XOVR as a relay board for some AC switching.
 
What I wanted to do was use the board to provide lighting control for 6 bedroom/hall closets via outputs from the M1.
 
Was going to centrally mount in a UB12 and in one corner of the same UB box place a 4x4 junction box for most of HV wiring except the conductors feeding to the board of course.  The only LV wires would be the databus cable.  I only need 6 relays so figure the #7 and #8 relay spot which is next to the databus would be empty so can provide decent clearance between the LV / HV wiring.
 
Too risky?

 

[ano]

Relays are so 2012.
 
You might want to look at these:
http://www.opto22.com/site/pr_details.aspx?cid=3&item=120A10
 
No moving parts, 4000V isolation between input and output, work in all conditions, no coil voltage spike.  I use them all the time and they work great.