Help wiring new house

[jeffesonm]

That is super helpful, thanks Wayne, especially all the details on conduit fill, derating and box size.

Yes schedule 40 PVC. The electrician running the service did specify a GE panel and I understand their AFCI breakers work with MWBCs. That being said, I will probably just run complete circuits with individual neutrals. After mapping everything out it looks like I only need a handful of circuits across the various conduit runs.

A1
2 x 12 awg stranded - 20a - master bathroom (receptacles, fan, lights)
2 x 12 awg stranded - 20a - master closet and water heater (gas, tankless)
2 x 12 awg stranded - 20a - laundry
1 x 12 awg solid - ground

A2
2 x 12 awg stranded - 20a - guest bedroom (receptacles)
2 x 12 awg stranded - 20a - minisplit
1 x 12 awg solid - ground

B1
2 x 14 awg stranded - 15a - lighting
2 x 14 awg stranded - 15a - lighting
1 x 14 awg solid - ground

Seem reasonable? I need to measure out the lengths and buy some wire... might end up just using 12 awg for everything rather than buying both 12 and 14.

 

[Reach4]

On the conduit side, a 3/4" Schedule 40 (?) PVC conduit

The PVC conduit I have seen is gray schedule 80.

 

[Sponsor]

 

[wwhitney]

The PVC conduit I have seen is gray schedule 80.

In plumbing, all the PVC Schedule 80 pipe I've come across is grey, presumably allowing its use exposed to sun. Al the PVC Schedule 40 pipe I've seen is white, presumably not allowed to be exposed to the sun.

In electrical, all PVC conduit is grey and allowed to be exposed to the sun; it is available as either Schedule 40 or Schedule 80. Schedule 80 is required where the conduit is exposed to damage; what exactly that means is an AHJ judgement call for the most part.

So my "(?)" meant "I'm assuming you used Schedule 40, because there's no reason in your application to have used Schedule 80, but you need to confirm, as Schedule 80 has a smaller ID, so the conduit fill allowances are smaller."

Cheers, Wayne

 

[Reach4]

In plumbing, all the PVC Schedule 80 pipe I've come across is grey, presumably allowing its use exposed to sun. Al the PVC Schedule 40 pipe I've seen is white, presumably not allowed to be exposed to the sun.

In well downpipes, schedule 80 is common, screwed into couplings. Those are normally white, and come in 20 ft lengths more commonly. There is also schedule 120 and schedule 160, and maybe more. Well downpipes normally don't get exposed to the sun.

For pcv outside of the well, regular schedule 40 is common. It should be protected from the sun. Paint is one way to do that. Many wells lack the sun protection.

 

[wwhitney]

The electrician running the service did specify a GE panel and I understand their AFCI breakers work with MWBCs. That being said, I will probably just run complete circuits with individual neutrals.

Let me make a pitch for MWBCs. The upside: (a) less material used (b) less voltage drop under combined loading (c) less conduit fill, so easier pull. The downsides: (1) issues with AFCIs (not a problem with GE) (2) handle ties required (minor) (3) greater conceptual complexity (a one time cost for you).

Seem reasonable?

No reason to use solid for the EGC. You can get green jacketed stranded. Using #12 for everything in the conduit is reasonable, rather than buying multiple sizes. You're going to be switching over to NM at the far side of each conduit run, correct? You can still use #14 NM with a #12 THWN-2 homerun; that will require a 15A breaker, and for documentation you can put a little note on the relevant #12s in the panel to the effect of "#14 NM downstream" if you like. There's a slight trick to using a wire nut to connect stranded to solid, or you could just use Wago 221s (what I am doing on the current house I'm wiring.)

Let me suggest an alternative conduit plan:

A1: 3 x #12 MWBCS (one spare conductor as you only need 5 2-wire circuits) plus 1 EGC = 10 #12s
A2: spare
B1: 1 x #12 MWBC plus 1 EGC = 4 #12s
B2: spare
C: unspecified

Cheers, Wayne

 

[wwhitney]

In well downpipes, schedule 80 is common, screwed into couplings. Those are normally white, and come in 20 ft lengths more commonly. There is also schedule 120 and schedule 160, and maybe more.

Thanks for the info, I have no knowledge of wells. And I agree, covered in paint => not exposed to the sun.

Cheers, Wayne

 

[Aaroninnh]

What circuits will I need? That would help plan what if any other conduit runs I might want. So far I've got:

• Microwave - 15a, 14g
• Cooktop (gas) and range hood - 15a, 14g

Is the range hood going to be hard wired or cord and plug connected? Remember if it has a cord and plug, it is required to be on a dedicated branch circuit and can't be shared with the cooktop.

Also, check the single wall oven. Many single wall ovens only need a 20A OCPD and 12AWG wire.

As to the bathroom, I agree with wwhitney that lights and fan can share the same circuit as the bathroom receptacles, but be aware that is only the case if each bathroom gets its own circuit.

 

[jeffesonm]

Definitely schedule 40 PVC that is gray. Yes plan is to switch to NM-B at the far ends of runs. Conduit C is just a shortcut for a three way light switch on either side of that room.

@Wayne - You do make a compelling case. Most appealing is having spare conduit leftover for future use.

Just to reiterate so I understand correctly, each MWBC consists of two hots and a shared neutral running from the panel to the junction box at the far end. There each circuit splits off into it's own romex with hot/neutral/ground. In the jbox each MWBC has its two neutrals tied together with the shared neutral that goes back to the panel. All grounds are tied to the one common EGC.

Also the mini split calls for a two wire 15 A 220v circuit, so that one would not be a MWBC, just have two hots from the panel and transition 12/2 romex at the jbox.

So 2 x #12 MWBC = 6 CCC, 2 x #12 for mini split = 2 CCC, plus 1 EGC. Is that all correct?

@AARON - I plan to run 8/3 for the oven, in case I want to make it a double later on. Each bathroom will have its own circuit, with receptacles, lights and fan all on that circuit. The one bathroom has the fan in the shower space so it will tie in after GFCI. Good call out on the range hood... have not picked one yet. Is that the same for the range? Meaning cord/plug = dedicated circuit?

Also there is one short conduit run not pictured that goes to a floor box in the slab, near where the "island" would be. In quotes because it will be a large work table that happens to be near the middle of the kitchen, but definitely not an island that would be subject to the electrical requirements. Based on previous discussion, do I understand correctly I can run 12/2 UF from a receptacle in the wall, down into and through the conduit and then connect to the receptacle in the floor box? That would be easier than trying to terminate the conduit in an accessible box as none line up where it comes up from the slab and into the wall.

 

[Aaroninnh]

@AARON - I plan to run 8/3 for the oven, in case I want to make it a double later on. Each bathroom will have its own circuit, with receptacles, lights and fan all on that circuit. The one bathroom has the fan in the shower space so it will tie in after GFCI. Good call out on the range hood... have not picked one yet. Is that the same for the range? Meaning cord/plug = dedicated circuit?

Gas range does not need a dedicated circuit, just a hood if it is cord and plug connected. Reasoning was the NEC wanted to make it easier to convert a regular hood to a microwave hood later which draws a much higher load. I know you have a separate microwave already, but the code doesn't care.

As to the single oven, running larger wire is always fine but put in the breaker matched for the stove (20A, or maybe 30A, install instructions will tell you).

Also there is one short conduit run not pictured that goes to a floor box in the slab, near where the "island" would be. In quotes because it will be a large work table that happens to be near the middle of the kitchen, but definitely not an island that would be subject to the electrical requirements.

Not sure I follow you? A flat work space/table, fastened to the floor, in a kitchen area is likely to be considered an "island" by the inspector/AHJ regardless of what label you give it. If its not fastened to the floor than you're all set.

 

[wwhitney]

Is that all correct?

Yes, with the proviso that the hots have to be on opposite phases. So verify 240V between the hots. A common error is to use a tandem that provides two connections on the same phase, not good.

Based on previous discussion, do I understand correctly I can run 12/2 UF from a receptacle in the wall, down into and through the conduit and then connect to the receptacle in the floor box?

If the receptacle is in the floor box, yes. Floor receptacles require special boxes listed for the purpose. If the receptacle is in a box mounted to the table somehow, protection of the cable between the floor and the box is an issue. As is whether that would turn the table into a fixed island, which would require meeting the island receptacle requirements.

Cheers, Wayne

 

[jeffesonm]

@aaroninnh - It is not fastened to the floor so should be good there.

@wwhitney - Receptacle will be going in a Raco concrete floor box so it sounds like UF will work.

Also thanks all, really appreciate the help.