wiring for garage door openers?

[JosephP]

At the barn... I'm running some wiring for motion lights outside the doors.  Thinking, should I pull 14/3 w/ground wire instead of 14/2 wire w/ground so I can use the red for garage door openers when I'm ready to install those?

They will be jackshaft openers...  I'll probably use 3/4HP openers for the 10x10 doors.  (https://www.amazon.com/dp/B07H4BGY1W/).  Maybe bigger for the 14x14 doors?

A)  Is it OK if I put multiple doors on the same circuit.
B)  Is 14 gauge wire adequate?  When I look up amps for 3/4HP, I see 13 - which means that is pushing it (making answer to A "no").  But when I look up electrical requirements from Chamberlain (https://support.chamberlaingroup.com/s/a...or-openers) it says their 3/4HP openers require 5 amps...which would seem to suggest no problem putting at least 3 on the same 15 amp breaker?

as I type through this, maybe I just pull 14/2 for the lights and then 14/3 for 2 separate circuits for the openers???? (4 doors total....well, 5, but one is on another wall and I'll pull that from the subpanel because it is much closer).

[TDKPE]

Where are these circuits originating?  If in the same building, you can do whatever you want.  If in another building, the NEC doesn’t allow more than one circuit to an outbuilding, though a 3-wire circuit with a 2-pole breaker, like to a sub panel, or to two different loads, is still considered a single circuit in that context.  

If you’re using 14-3 or 12-3 to power these different doors, you need to have a handle tie connecting the two single-pole breakers so when manually opening one breaker, the other opens also.  A 2-pole breaker is also acceptable, where either side tripping on over current also trips the other, and of course they both open when you operate the handle.  2-pole is also required if any 240V loads are on the circuit, or if both hot legs are on a single strap (like a duplex receptacle with one hot leg to each individual outlet), but that probably doesn’t apply here.

There are lots of rules in the NEC for multi-motor circuits, but I don’t know how they’d apply to garage door openers.  Usually you use the table values based on hp rating, and you can put multiple motors on a single circuit, using 125% of the current rating of the largest motor, but those things are more appliance than motor, in the sense that you can’t/won’t replace the motor with a higher current motor of the same hp rating (which is why the table values exist).  

Being that door openers are intermittent loads, I think I’d lean toward putting up to three of them on a 20A circuit (at 5A ea), or six of them on 12-3 copper (from a sub panel), or just two runs of 12-2, but I’d also ask the inspector, if there is an inspector, before doing the work.

Edit: On re-reading your question, since there are really four doors, I’d use 14-2 or 14-3, with one hot per pair of doors at 5A each, unless the inspector has an issue with it. But two door openers on a 15A garage circuit is pretty standard.

[JosephP]

A) originates in building- not an out building. 60x80. Main panel is in NE corner. Subpanel is on W wall. 4 doors on S wall. 1 door on W wall.
B) no inspections - agriculture building in unzoned township
C) I was thinking 2 breakers on separate poles...I thought that is what was required for sharing neutral and ground with 3 wires? I have space in the panel...or is a 2 pole better?

So, as of now I think you confirmed: I pull a 14/3 and use black for 2 doors and red for other 2.

Thanks!

[TDKPE]

C)  I was thinking 2 breakers on separate poles...I thought that is what was required for sharing neutral and ground with 3 wires?  I have space in the panel...or is a 2 pole better?

Being that it's a multi-wire branch circuit (NEC term), the neutral is shared, and therefore you must use a handle tie to connect the two breakers.*  If you didn't, someone could shut off just one breaker and lift the neutral thinking the circuit is dead, but the neutral would be hot once removed from the neutral bus since it would still be connected through whatever load is on that half of the circuit to the 'other' hot conductor, which is not disconnected.

You can either use an approved handle tie with two adjacent breakers, or a two-pole breaker.  Either method uses two full-sized slots.  The only functional difference with a 2-pole breaker is that if either pole is overloaded, they both trip open.  With a handle tie, if one trips, only that one opens, leaving the other still hot.**  The handles are free-trip type, so when one trips, the tripped handle may not carry the other, but internally it will still trip.  You have to open both together, then re-close them to restore power.

Being garage doors, I would use a handle tie.  If one stalls and trips the breaker, there's no good reason all four doors should go dead.  The BORGs stock some handle ties, but they're readily available online or in electrical supply stores.  Just use one approved for the make and series of breaker you're using, if not using a 2-pole breaker.

*Edit 1: From memory, I don't think handle ties were required for MWBCs that didn't power 240V loads, or two circuits on the same strap, but I believe the NEC changed not too long ago to require them as a minimum for all MWBCs.

**Edit 2: Most brands of two-pole breaker have a handle tie (but not Square D QO series), but they're true 2-pole breakers with independent trip triggers but common trip mechanism.

[Roly]

Unless I am adding to a circuit that has 14 ga wire, I just install 12 ga wire and have the extra capacity if you would want to add on.  Check the cost of 12-2 vs 12-3, 12-3 is almost twice the price of 12-2.    I don't see much of an advantage to get into multi wire circuits.    This way if a opener trips the breaker the rest would still be working.  Roly

[JosephP]

Cost is one factor. However, the fewer MC wires I have to pull 12 ft up on a ladder around each post in the pole barn, the happier I am. Also, if I keep trying to pull too many, at some point I will run out of good places to hang the wire...

I'm certainly not an electrician, but I agree that running 12 gauge instead of 14 is generally a good idea to have the capacity.

I'm using 14 gauge for LED lights. Those are hardwired so I don't imagine adding extra load. While I was pulling those, I got to thinking about the garage doors... That's what got me started with questions here! I am expecting garage doors will be dedicated circuits as well even if not hardwired. Finally, I have about 150'+ of 14/3 left over from putting all the ceiling lights on three-way switches. If I can put that to use for the garage doors, great! However if I am better off with 12 gauge, that's what I would do... It's why I asked so I appreciate the input!

[Roly]

If you have the 14-3 already I would use it also.  Just thought if buying new I would go 12 because of cost difference is not much.  Roly

[srv52761]

Gfci?  Even for openers, I think they are now required... But, I could be wrong...

[JosephP]

Gfci?  Even for openers, I think they are now required... But, I could be wrong...

not permitted/inspected, so no.


If I were convinced that would be beneficial, sure.

[JosephP]

If you have the 14-3 already I would use it also.  Just thought if buying new I would go 12 because of cost difference is not much.  Roly

Thanks - appreciate the explanation of the logic!  It does help you make recommendations when you have all the variables