EMT or PVC in Bathroom?

Question

OK, so I am wiring my cabin (actually a small house, 16x24), and I have a 6x8 room that will eventually become a bathroom, and a nook that will be a kitchenette. All the wiring in the house is surface mounted EMT conduit & metal boxes (long and goofy story about why this is so and not romex in the walls)

In the bathroom, is there that much of a safety advantage to running PVC conduit? Or is EMT and metal boxes okay? Of course all outlets/switches/boxes are to be grounded. My worry is the steamy shower air settling and condensing to drops on the parts inside the boxes.

Also, after some research, I have interpreted that:

• In a single bathroom, outlets/lights/and fan may be on the same breaker and it must be GFCI protected.
• In kitchens, the convenience receptacles must be on their own 20A GFCI-protected breaker with 20A outlets, separate from lighting. (not including fridge/oven etc which must be separate)
• In kitchens the lighting circuit does not have to be GFCI or CAFI protected.

So (assuming I'm correct in my research above) my plan is:

• One CAFI/GFCI 20A circuit to the bathroom with two 20A outlets, a vent fan, and a surface-mount LED light fixture.
• One CAFI/GFCI 20A curcuit to the kitchen convenience outlets, in EMT conduit with 20A outlets in metal boxes
• One CAFI 15A circuit to the kitchen light fixture (same fixture as bathroom). I know CAFI isn't necessary (right?) but I assume it can't hurt to have the extra safety margin.
• One CAFI/GFCI circuit to power the fridge.

Answer 1

• if a circuit powers receptacles in 2 bathrooms, the only other things that can be on it are receptacles in any number of bathrooms.
• if a circuit powers receptacles in only 1 bathroom, the only other things that can be on it are other (hardwired) loads in that same bathroom.

The reverse is not true; a hardwired load in a bathroom can be powered off any convenient circuit (unless its rules prohibit that). That is a good idea so you don't plunge the bathroom into darkness when you trip a GFCI/breaker. Those hardwired loads do not need GFCI protection.

One thing I would do in bathrooms is run a ground wire in the conduit. That gives you "belt and suspenders" grounding in the off chance of an EMT rust-out or physical damage. Just because good grounds are so helpful there.

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There need to be two 20A circuits that serve kitchen countertop/convenience receptacles, as described in RME's answer.

There is nothing wrong with more. Any kitchen appliance which uses heat aims to use 1500W - that means a 20A circuit will trip with two of them, and the savvy chef must learn his kitchen's circuits and put his appliances in possibly awkward positions. Therefore, it is not excessive to have a breaker per socket - done by feeding it from two 1-pole GFCI breakers handle-tied, or a 2-pole GFCI (as MWBC). The handle-ties are required due to common-yoke rules.

This kind of thing is why we say "get panels with lots of spaces".

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It's not illegal to put the fridge on one of the two kitchen general countertop circuits. However...

I generally do everything I possibly can to assure that the refrigerator is on a dedicated circuit.

GFCI and AFCI protection has specific reasons for existing; these reasons being the use case. An all-steel refrigerator with all its mechanical equipment shielded, on a dedicated homerun 1-socket circuit, is not a reasonable use-case for GFCI or AFCI. They provide a negligible safety margin, and introduce a different safety problem: spoiled food. As such I recommend using every trick possible to avoid a fridge being on a GFCI or AFCI.

Being a dedicated circuit averts the nightmare scenario: the GFCI trips, fridge warms up, is reset because other loads are interrupted, the resetter is oblivious that the fridge is also on that circuit, fridge re-chills, and food is used as if it's good.

A dedicated circuit reduces the worst-case scenario to a GFCI nuisance trip causing a warm fridge and a bunch of spoiled food.

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AFCIs are designed to catch two types of defects: first, electric blankets - did I say electric blankets? I meant arc-faulting wiring inside any appliance... and second, faulty wiring in walls (i.e. backstabs). EMT conduit and steel boxes greatly ease the latter. EMT doesn't stop it from arcing, but it's a good thermal conductor and will spread heat away from the arcing point before it can reach combustion temps. When insulation melts enough to let a melting "hot" touch the conduit, it will cause a bolted fault and trip the breaker. This is no help if it's a melting neutral.

All that to say, in EMT, AFCI is not my highest concern, unless I have a reason to doubt the appliances.

Answer 2

EMT is okay for wet areas, in fact it's widely used in outdoor settings. If you're concerned about moisture, you could use compression fittings and metal boxes intended for wet settings. However, they'll likely be more expensive and may not be needed (others may confirm/deny).

Answer 3

It's not a bad plan except NEC requires at least 2 - 20A circuits in the kitchen for small appliances. These circuits can also be used in the dining area, pantry and breakfast nook. That's Article 210.52 (B)(3).

Good luck.