Second guessing 120v wiring from 3phase.

[dirtybug]

I've been asked to help my church install 4 circuits to outside receptacles from a 208y 120 3 phase panel. Being on the residential side I haven't been in a 3 phase panel in 15 years and I'm second guessing myself thinking there's a big "duh" issue I'm missing, double check me here.
Plan is to have four single pole 20 breakers, running 3/4 conduit 30" penetrating wall into weatherproof boxes with gfci's and bubble covers pulling four 12ga hots four neutrals and a ground.
Seems pretty straight forward but I'm getting myself hung up on the 3ph.
Another question is if I used gfci breakers could I feed each receptacle with two circuits splitting the yoke hot and neutral having two duplex receptacles and four circuits? I know residentially I'd have to use 2p breakers and a mwbc but wouldn't want that here. Thoughts


PA 2014 nec

 

[augie47]

I've been asked to help my church install 4 circuits to outside receptacles from a 208y 120 3 phase panel. Being on the residential side I haven't been in a 3 phase panel in 15 years and I'm second guessing myself thinking there's a big "duh" issue I'm missing, double check me here.
Plan is to have four single pole 20 breakers, running 3/4 conduit 30" penetrating wall into weatherproof boxes with gfci's and bubble covers pulling four 12ga hots four neutrals and a ground. Likely to result in box fill problems
Seems pretty straight forward but I'm getting myself hung up on the 3ph.
Another question is if I used gfci breakers could I feed each receptacle with two circuits splitting the yoke hot and neutral having two duplex receptacles and four circuits? I know residentially I'd have to use 2p breakers and a mwbc but wouldn't want that here. Thoughts
Feeding 2 circuits to one yoke would require simultaneous disconnect.


PA 2014 nec

see above

 

[zbang]

Another question is if I used gfci breakers could I feed each receptacle with two circuits splitting the yoke hot and neutral having two duplex receptacles and four circuits?

As Augie mentioned, simultaneous disconnect, but also why would you want to split the duplexes? Unless the loads are going to be specific high-draw units (i.e. a fryer), folks are going to be looking for more places to plug in. Save some future hassle and install one duplex per circuit; whether in single or double gang boxes depends on how much space there is and how they'll be used.

 

[LarryFine]

You can run two 3-wire MWBCs, using handle ties or 2p breakers, on 208/120v just like you would on 120/240v. I would recommend two 2-gang boxes with two GFCI receptacles in each one.

 

[GoldDigger]

Note that fill and wire cost aside, you get lower voltage drop with a three phase MWBC (full boat) but not with a 2 of 3 MWBC.

Sent from my XT1585 using Tapatalk

 

[dirtybug]

As Augie mentioned, simultaneous disconnect, but also why would you want to split the duplexes? Unless the loads are going to be specific high-draw units (i.e. a fryer), folks are going to be looking for more places to plug in. Save some future hassle and install one duplex per circuit; whether in single or double gang boxes depends on how much space there is and how they'll be used.

Makes sense to us but the church doesn't want to see anything mounted to the wall, they can't have that so limiting what's seen is second best. I.e. One two gang box instead of two. Especially since it would be two separate two gang boxes as 4g bubble covers are like unicorns. A 50a receptacle to feed a portable distribution box would be perfect but their funds and my unfamiliarity are steering us in this simpler direction.

 

[LarryFine]

Note that fill and wire cost aside, you get lower voltage drop with a three phase MWBC (full boat) but not with a 2 of 3 MWBC.

True, were his needs a multiple of three. He could run a full boat and a separate 2-wire circuit, but my suggestion of two 3-wire circuits saves on the cost of breakers. 2-poles cost about the same as two 1-poles; 3-poles are $.

 

[Jraef]

Makes sense to us but the church doesn't want to see anything mounted to the wall, they can't have that so limiting what's seen is second best. ...

I love it... "I want my stuff to work, but I don't want to have to look at what it takes to make that happen."

I guess that's what you learn to expect in a religion too!