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Could I get another set of eyes on this schematic? It's a standard bathroom, however I'm adding a whirlpool tub pump, a whirlpool heater, and a macerator unit for waste discharge. I've read the instructions a million times, but I'm a little outdated on code requirements. I'm in Indiana.

The Macerator unit does not specify it need be on a dedicated circuit, but requires a 15A GFCI.

The whirlpool requires 20A GFCI dedicated.

The whirlpool heater requires a 15A GFCI dedicated.

Instructions say to bond the frame lugs of the heater to the whirlpool pump, then back to the electrical panel ground with 8ga. wire. I see the hardware store sells bare copper 8ga bonding wire, so that's what I intend to use.

Have I overlooked anything?

final layout

SlowSL
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  • What does the macerator nameplate list for the amperage it draws? That can affect whether it needs a dedicated circuit (even if the instructions don't state that explicitly) or not. If it takes more than 7.5A, (half the circuit capacity) it needs to be dedicated. – Ecnerwal Feb 02 '23 at 14:56
  • @Ecnerwal, My thought was worst case a hair dryer (up to 15-16 amps) and the macerator activated at the same time would be right around 20 amps. Although highly unlikely both will be used at the same time, it's still a possibility. Here are the specs on the macerator.. Amperage, 4.5 Amps (Max) ; Motor, 0.5 HP. My initial thought was it would be easy enough to rewire to dedicated if needed since everything that would need changed over would be easily accessible, but I guess it would only cost an extra GFCI outlet and small amount of wire for piece of mind but running low on panel box slots. – SlowSL Feb 02 '23 at 15:31
  • If the whirlpool and heater each require a dedicated circuit, shouldn't that mean you need three separate circuits? – keshlam Feb 02 '23 at 15:31
  • If the light/vent does not involve a heater-vent, should be all kinds of room on that circuit for a measly 4.5A load. Certainly don't need to dedicate at that amperage. – Ecnerwal Feb 02 '23 at 15:51
  • @keshlam each color on my schematic is a separate circuit, so there are (4) separate circuits. – SlowSL Feb 02 '23 at 19:59
  • @Ecnerwal, that brings up a good point I didn't think about... I think I'm going to want a heated vent fan, I'll have to re-think this, looks like they can draw around 10amps. – SlowSL Feb 02 '23 at 20:01
  • The ones that have come up in a question recently specify a dedicated circuit, so - shop carefully. https://diy.stackexchange.com/q/265872/18078 – Ecnerwal Feb 02 '23 at 20:14
  • On the phone, the colors weren't distinct and the lighting circuit was by far the most visible thing; apologies for misreading. – keshlam Feb 02 '23 at 23:04
  • Since you're using bare copper bonding wire, will it be in contact with dissimilar metals along its run (for example metal studs)? This may cause galvanic corrosion. Consider using insulated wire and stripping it only where it terminates on a (listed) connector. – Theodore Feb 03 '23 at 15:50
  • Personally I'd probably put all the GFCI/AFCI protection in the panel instead of using dead-fronts. Yes it's generally more expensive but when you add up the plain breaker, deadfront, box, and cover plate, it's not a huge difference. The labor savings of not having to mount a box, cut the necessary hole in the drywall, install the deadfront, etc. is worth it. – nobody Feb 03 '23 at 18:30
  • See also this discussion. – Harper - Reinstate Monica Feb 04 '23 at 03:27

1 Answers1

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A few rules you need to know about.

A light or fan in the shower needs to have GFCI protection (or be low voltage). That can be tapped off the countertop or other receptacle if that receptacle circuit serves only this bathroom. (210.11(C)(3) exception).

As of NEC 2020, bathroom rules have changed somewhat. Previously, ALL receptacle outlets in a bathroom had to be 20A and follow "only bathroom" rules in NEC 210.11(C)(3). As of NEC 2020, this only applies to receptacles which serve the countertops - other receptacles in other areas can be from circuits that serve other rooms. So for instance, a towel heater receptacle could be on the same circuit with bedroom receptacles. Even if your state is on NEC 2014 or NEC 2017, asking your permit issuer to let you use the 2020 interpretation is perfectly reasonable.

Heaters require a 125% derate. Suppose you have a 960 watt heater (8 amps). You must provision it exactly the same as if it was a 1200 watt (10 amp) heater. And THAT is why the savvy manufacturer made it 20% smaller than a nice round number). This is often incorrectly called the 80% rule (implying it applies to every load; not quite).

Installation instructions must be followed (implied: must be read). NEC 110.3. If the instructions say "dedicated circuit" then that's that.

If you already own (or have to buy) 12 AWG wire, the way spools are priced it's probably cheaper to just buy/use more #12 than buy a separate spool of #14 just for 15A circuits. Use of #12 on a 15A breaker/circuit is allowed.

Fastened-in-place loads are treated as hardwired loads, in the following rule: If fastened-in-place loads take up more than 50% of circuit ampacity, then no receptacles at all are allowed on the circuit. Obviously, for a fastened-in-place plug-in load, the thing is allowed to have one socket for itself... so you need to use a single receptacle there (1-socket, simplex receptacle).

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You may notice a problem. With a simplex receptacle, how do you get GFCI there? You use a GFCI breaker; you use a double box with a GFCI deadfront in the other gang or down at the panel; or you cheat and do this. The switch doesn't need to go to anything; it's just there to prevent a second socket from existing.

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You can have 2 or more fastened-in-place devices on a circuit, however in that case you sum their ampacity before applying the "is this 50% of the circuit?" rule. So for instance a 6 amp and 1 amp hardwired load on a 15A circuit is 7 amps, not quite half so it can have receptacles.

All this means, then...

If a 15A circuit will suffice for the fastened-in-place load, then it is legal to use it. You're not forced to a 20A circuit merely because it serves a socket (per NEC 2020 rules).

If two fastened-in-place loads can share a 15A or 20A circuit and still be under the ampacity (after 125% derates applied if applicable), then you can do that.

GFCI receptacles in difficult-to-access places are difficult for people to find when they're having a problem. That is a case where I'd go for a GFCI breaker or deadfront at the panel.

Having all lights on the receptacle GFCI isn't the smartest move. That is the GFCI people are most likely to trip, and you don't want them plunged into total darkness if they do. I think people do this because of misreading 210.11(C)(3). Bathroom wired-in lighting can be on any circuit in the house that isn't restricted by some other rule (e.g. not the furnace, electric dryer or kitchen receptacle circuit).

Putting the shower stall light/fan on one of the bathroom GFCI circuits is reasonable.

Note that GFCI receptacles allow 2 wires on each of the screw terminals, so it's easy to e.g. have a GFCI outlet in the bathroom, power some lights off the LINE terminals and the shower stall light/fan off the LOAD terminals.

GFCI or AFCI deadfronts at the panel

I for one am cheap, and really like Pushmatic. As such, I enjoy GFCI or AFCI deadfront receptacles located right next to the panel.

Here's the secret with those: Install them "2 at a time" in a 4-11/16 (aka 120mm) square steel box. With a domed cover (or mud ring if flush). Why that size and not 4" box? Space. One GFI is an extremely tight fit in a basic box, two GFCIs are an extremely tight fit in a common 4x4 box The tight fi t causes no end of problems - cable and conduit entries can only go in top or bottom, and you must strategize where to position the wire nuts so the GFCI doesn't bottom out on them. It sucks. However with a 4-11/16" box you have elbow room both alongside and behind.

I also like EMT conduit from panel to box, because that takes care of ground for you. 1/2" EMT will easily accommodate the 8 wires you need to bring 2 circuits to the G/AFCIs then 2 circuits back into the panel for connection to their circuits. Remember to tape hot+neutral for each circuit together to identify them as pairs - code requirement. Use #12 THHN black and white wire.

Harper - Reinstate Monica
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  • Thank you for this. This helps tremendously. I'm at work, but I'll re-read all this in detail and make sure I understand everything before I go any further. I've updated the schematic, adding it to the original post. I've separated a circuit, as well as added a dedicated vent fan circuit for use with a heater. I've changed to simplex recepts where applicable and added dead faced GFCI's located behind the wall, but also include two alternative locations after thinking about ease of access if something goes wrong. One being next to toilet, which seems silly, the other next to panel box. – SlowSL Feb 03 '23 at 15:32
  • The heater instructions as well as macerator require a 15A circuit. I'd assume that's a minimum, and 20A would be perfectly fine. I noticed 15A dead faced GFCI's are not available, at least not in stores around here, so I will use 20A for both the heater and whirlpool pump. There is not a problem the way the circuits are laid out since they are 20A, is there? I should be able to use 15A or 20A simplex recepts at their locations, correct? – SlowSL Feb 03 '23 at 15:38
  • I'll also add that all wiring will be 12/2, even 15A circuits. – SlowSL Feb 03 '23 at 15:39
  • One more thing, I didn't realize a tub skirt was considered a fixed entity. This is a drop in/alcove tub without a skirt, so the front face will have a dummy wall with some type of finishing. The plan was to build in a large access incorporated into that face for service/access. If I go that route, I'm able to use GFCI's under the tub, it looks, correct? – SlowSL Feb 03 '23 at 16:08
  • @SlowSL "dead faced GFCI's located behind the wall" I presume you mean that it's facing into another room, not behind drywall. A) buried behind drywall (or other non removable covering) is a code violation for any junction box, and B) How are you going to reset a tripped GFCI if it's behind the drywall? Again, presume you're taking the appropriate action, but just double checking... – FreeMan Feb 03 '23 at 18:30
  • @FreeMan, sorry, my wording could have been better. There is an open space between two walls where the macerator and where the dead faced GFCI's would possibly be. There is a large access from the laundry room. I think my mind is made up, though, the dead faced GFCI's will likely go right next to the service panel to avoid moving the access panel. – SlowSL Feb 03 '23 at 19:12
  • @SlowSL if an appliance requires a dedicated circuit and calls out a particular circuit breaker, that breaker is part of the appliance protection and larger breaker would degrade its protection. However larger wire is always OK. GFCIs don't care how much current is drawn through them, not their department, they're not a circuit breaker. So the 20A rating on a deadfront is a "never exceed" not a mandate. Socket GFCIs only differ by the T-shaped neutral, internally they are the same. When only 1 socket is on a circuit, the socket must match the breaker. – Harper - Reinstate Monica Feb 03 '23 at 19:27
  • @SlowSL GFCIs say "test monthly" - think about that for access. My tub backs up to a hallway. There is a tastefully trimmed cabinet door with brass latch. Open the door and you're looking at the backside of the tub faucet. Guess how much drywall and paint I must do to change my tub faucet? NONE LOL. Therefore my tub faucet is maintained tip top (because I can). That would be a good place for GFCI deadfronts. Main thing is, people need to be able to find it, or else they will presume broken wires in walls and call an electrician. Who will show you where the reset is, and charge $150. – Harper - Reinstate Monica Feb 03 '23 at 19:34
  • @Harper-ReinstateMonica, thanks for clarifying. I guess I assumed manufacturers are stating the lowest amp breaker which would not be tripping all the time. In the same sense, you can plug in any device with a 15amp plug to a 20amp outlet. I see now somewhere in the code states that you must use the amperage recommended in the manufacturers instructions. So adjusting the circuit to your points.... using a 15A breaker in the box, a 20A dead face GFCI (all that is available), and a 15A simplex receptacle, all would be good, correct? – SlowSL Feb 03 '23 at 20:02
  • Okay, I've updated the schematic and added it on the original post, does this look better? I hope this is the final time I revise this layout. The macerator, pump, and heater are all on dedicated circuits now, all have dead face GFCI's protecting them with easy access to them. The breaker sizes in the panel box are what the manufacturer for each device states, and the outlets match the breaker size. I feel like I need to pay you for your time with this! – SlowSL Feb 03 '23 at 20:36
  • @SlowSL yes, 15A breaker-20A GFCI-15A socket is fine. There is no reason for a 15A deadface to exist. It's not a circuit breaker. It's looking good. Maybe I should start a Youtube channel and get a Patreon lol. – Harper - Reinstate Monica Feb 04 '23 at 03:59