*
Whoever wired my disposal back in the early 60s, which I am replacing, wired it with a switched neutral. This appears to make some sense, since the switch is in a wet location right above the sink.
I have since installed a GFCI in that 2-gang outlet, and was thinking about wiring the new disposal as “load” on the GFCI with a switched hot, which I imagine is the proper way to do it. However, since this outlet and switch are in a wet location, the GFCI often trips. This would be a pain for the disposal. Perhaps the switched neutral is as safe and more convenient. Any thoughts on this?
Replies
*
I don't see how switching the neutral makes sense because when the disposal is off (the switch is open), the "neutral" is hot. And so is the disposal. Whereas if the hot were switched properly, none of the wires, motor windings, etc would be hot except when the disposal is operating. Very few people will try to service a spinning disposal, but some may assume that turning off the switch turns off the power. Outlets under the sink are supposed to be GFCI but if a single receptacle is filled with the plug of a dedicated appliance, you can have a non-GFCI outlet in the kitchen. This is definitely better practice for the fridge - a single 120-volt, non-GFCI receptacle dedicated to the fridge. Because if a GFCI trips everything the freeze will thaw. I also wired my under-sink outlet that way to avoid nuisance tripping of a GFCI by the disposal motor.
In summary, switch the hot (definitely) and don't GFCI the disposal (your choice). -David
*Switched neutral? NEVER! Won't pass code and could shock the bejeesus out of the next unsuspecting person tinkering with the wiring.
*NEC article 380-2b: Switches or circuit breakers SHALL NOT disconnect the grounded conductor of a circuit.fv
*FXDP,Switch the hot, not the neutral, for your and your family's safety. It's not safer than a properly switched hot. David explained it well.On the requirement for GFIs in the kitchen, the '99 NEC requires the countertop receptacle outlets to be GFI-protected, per Section 210-8(a)(6).Because the Code explicitly refers to countertop receptacles, other receptacles (such as undercounter outlets serving disposals) ARE NOT required to be GFI-protected. The official NEC 1999 Handbook (published by the NFPA) makes this clear by stating that"Receptacles installed for disposals, dishwashers, and trash compactors are not required to be protected by a GFCI." That goes for refrig outlets too. Be aware that having a single receptacle outlet "dedicated" to an appliance does not get you out of the GFI requirement, if the outlet serves the kitchen countertop. Any kitchen countertop receptacle outlet MUST be GFI-protected.However, there are exceptions in the Code that allow you to avoid the GFI requirement in a garage or unfinished basement (where GFIs are otherwise required). You can avoid the GFI requirement by placing the outlet so it is "not readily accessible", e.g., behind the appliance (freezer or fridge) and low enough so it would be difficult to use as a convenience outlet. See 201-8(a)(2), exceptions 1 & 2, and 210-8(a)(5) exceptions 1 & 2. In new construction, I usually put the kitchen fridge outlet at 32", and use a duplex receptacle (because the singles are more expensive). In the garage or basement, I go for 36" and DO use a single receptacle. Ditto for the laundry (washing machine) outlet (and the outlet for the lawn sprinkler timer, which you don't want to GFI-protect). I feel that in the garage or basement, the temptation is too great to plug an extention cord into the unused half of a non-GFI duplex receptacle outlet. And in fact as David mentions, a disposal (especially as it gets older) will sometimes leak enough current to nuisance-trip a GFI.If you're really worried about the disposal switch, there is a new product that's just the ticket. It's a switch that's mounted under the counter and which is operated by a pneumatic pushbuttom mounted on the sink or counter deck. No metalllic connection between the pushbutton switch and the AC power at all--just a piece of plastic tubing. Look for a brochure on it at any good plumbing supply; I believe it's an In-sink-er-a-tor product. I haven't installed one yet, but I can definitely see applications for it.Good luck.
*The switch last mentioned is also used for the jet controls in tubs.fv
*Thank you all for your replies. However, the situation I have does not quite conform to what you have described. The installation is 45+years old, and I have no idea if it met code at the time. Nonetheless, there it is, and I'm replacing the disposal!There is a two gang box in the splash above the sink. It gets wet a lot. In this box is a GFCI which I installed to replace the two prong outlet which was there, and a light switch wired to the disposal via flex conduit from that box, trough the wall, exiting the wall under the sink and going directly into the disposal. When I replaced the disposal, I figured the electrician who wired the thing originally must have had a reason, and I decided that reason must have been to avoid having a "hot" switch which is operated with wet hands in the wet environment around the sink. I guess that's a bad idea. To set things right via the easiest method, must I add a switched outlet below the sink for the disposer? Or can I just rewire the disposer so that it's a switched hot. Should that hot be "load" on the GFCI (which is always tripping)?Thanks again.
*CAP-Last year I installed a sprinkler timer/controller in a well house. I powered the timer off the Load lugs of a GFCI recep that is also powering a heat tape. Last fall when I winterized the system, the controller was showing an error code indicating incomplete electrical pathways at each zone valve. All 14 zone valves, pump relay, etc. functioned normally however, opening and closing at the controller's command.Your remark regarding NOT protecting a controller with a GFCI, for obvious reasons, caught my attention. I don't recall seeing anything in the install manual regarding this, though I may have overlooked it. The manual is with the install an hour away. I was planning on calling Nelson (The maufacturer) in a month or so when I started up the system for spring. Maybe you can help clarify-Lance
*Michael, why not move that box in the splash altogether? I've avoid a "wet alot" location for a kitchen outlet/switch.If this were exterior/or commercial application, you'd be required to have a "suitable for wet location" fixture.Problem with "neutral switching" is there's still a hot wire... waving in the breeze should you work on that disposal. The flex whip could contact the 45 year old (metal) plumbing... and arc. Or, could form a circuit through you.
*FXDP,George's suggestion is right on. Best to move the box away from the splash zone.About your belief that the switched neutral is safer than a switched hot--not so. Let me explain... In a normal switched circuit, the power (the hot conductor, AKA the black wire) goes to one terminal of the switch, and a "switched hot" goes from the switch to the load (light or disposal or whatever). The power return (the neutral) goes from the white wire of the disposal to the house wiring neutral. So, even when the switch is off, there is power present at one switch terminal. When the switch is on, current flows through the switch, down the switched hot wire and through the disposal, and then out on the neutral to your circuit breaker panel and back to the utility (where it eventually ends up at earth potential).In the case of a switched neutral, the black wire of the disposal is spliced directly to the hot (supply) of the house wiring. A wire from the white of the disposal leads to the switch, and from the other switch terminal a wire leads to the neutral of the house wiring. Because the power isn't switched until it's been through the disposal, the motor windings of the disposal are energized all the time. Turning on the switch completes the circuit by giving the electrons somewhere to go--the neutral conductor. Having the guts of the motor energized (at 120 volts) all the time is a very bad idea from a safety standpoint. The internal insulation of the motor deteriorates over time, and you can get enough current leakage to the disposal case and other metal objects (pipes) to cause a shock or electrocution. The small leakage will not trip the circuit breaker...but it's enough to stop your heart. More importantly, the switched neutral isn't any different from a switched hot. In either case, there is an "always hot" terminal of the switch. There has to be--you're switching the power with the switch.Please do it the right way, and move the box. Even if you have to pay for it to be done, what are the lives of you and your family worth?
*Definitely switch the "hot". I've been shocked several times by thinking that turning off the switch turned off the power, and then found out someone switched the neutral instead, bad idea as far as I'm concerned. I don't see why a GFCI is needed either, sure it would be safer?, but I bet you'd be running to your breaker box pretty often, I wouldn't do it. Get your hot leg from the Line side of the GFCI or strip back the hot wire in the middle and loop it over the switch then terminate it at the GFCI.P.S. Does anybody know of any good reason to switch the neutral?
*Adam,No, never heard a good reason to switch a neutral. However, some people mistakenly think that they've got a switched neutral they see a white wire terminated at a switch; in fact, it's just one conductor of a switch drop, and the installer hasn't re-identified the white as black. When I say switch drop, I mean the case where you don't take hot and neutral to the switch, just a hot supply and return. The X-10 guys hate that situation, and I almost never do it in new construction, but it's common in older buildings. Comes from the days when people went form gas illimination to electric light. They brought power to the fixture box in the ceiling and ran switch drops or legs to the switches.
*The only place I have encountered a switched neutral that was supposed to be is at a gas pump cutoff. FXDP - Don't assume the previous electrician had a good rreason for switching the neutral. Assume he did not know what he was doing. Instead of moving the often wet box, relocate the recetacle portion and keep the switch for the disposal, maybe adding a wet location cover if it is really wet.
*Never switch the neutral. Ever.
*I've got a bad feeling about that GFI jumping all the time, especially since you mentioned you had only 2 conductor cables. Where do you get your ground from? Is your GFI tripping because it gets shorted? I hope not. There is something inherently wrong with this picture... Also, you don't seem to understand the concept that your "load" end of the switched neutral is hot, because you don't understand that your disposal's motor winding is one continuous shellac-coated copper wire that is nothing but a path between the black and the white wires. If you were to take a reading between the load side of your switch and ground, you would most likely end up with 120 volts!Nonetheless, there is too much of a gray area involved here and I strongly suggest that you get your house wiring checked by a competent electrician.It sounds to me that your house is in dire needs of an electrical overhaul anyway.fv
*I second that! A constant tripping GFCI isn't normal, wet location or not. A recepticle in a location that gets directly isn't good or normal. Do it right....or fry the family. Jeff
*Francis: Don't worry about his GFI being on 2 wires. That's fine and there is plenty else to worry about with this situation. GFI work without a ground because they compare the hot and neutral currents. If they differ by a few milliamps for a fraction of a second, it trips. The GFI never knows what comes back on the ground, if anything. Which is good because it therefore protects against more kinds of ground faults. Only if you connect yourself as a load (between hot and neutral) will it not provide protection. Or if you haven't been testing it to notice its failure. Especially important in wet and/or exterior locations which damage the elctronics inside. Better to locate the GFI inside where it is dry and feed an outside or wetter outlet from there. FXDP: Get one of those LED outlet testers for $7. And test all your outlets. If some of your wiring is that funky, more might also be. Reversed hot and neutral or reversed neutral and ground can be dangerous but unnoticable because appliances will turn on just fine. The tester will identify those and other miswirings. -David
*David, thanks for the input, you are absolutely right. A GFI can indeed be installed in place of an ungrounded receptacle and do its job. It's not quite where I was coming from, mostly I am horrified at the picture of an ungrounded outlet being constantly splashed and tripping. That "hot" neutral is also being splashed, and who knows what's supposed to trip when hell comes loose...fvOn the good side of the '99 NEC...
*Okay, I see this has generated some interest.Thanks for the advice. I will correct the switch's polarity.As for the GFCI, it is grounded. The box is grounded through the conduit, and the GFCI is grouned to a pigtail screwed to the box. It trips a lot because it's really a wet location (2" above the flood rim of the sink -- lots of splashes. This is why I installed the damn thing in the first place. I got sick of listening to the thing buzzing and sizzling when it got wet.) The outlet is in a mud and tile back splash, so it's not moving until the kitchen is remodeled. So I guess I'll hook the disposal to the GFCI "load". Does this seem adequate? Thanks.
*FXDP, that GFI outlet is in the wrong place. GFIs are susceptible to moisture and get ruined under wet conditions, that is why we recommend putting the GFI in a dry place and then tap the load end of it to the desired location. If not possible, I would replace your current GFI immediately and keep on replacing it on a regular basis until you can do things in a more correct way. On the other hand, I wouldn't necessarily connect the disposal to the load screw of the GFI, because since you would only have one leg of the circuit to it, it wouldn't be able to sense a difference in load between hot and neutral, therefore not trip under ground fault situation. In another scenario, it might even disable the GFI altogether...fv
*Not to get picky here....but I'm picturing an outlet right behind the sink. What appliance needs to be plugged in over the sink.....and who has to do the plugging and unplugging? What do ya do...flip the "coin of death"? Why not run the disposal off that box, but can the receptical, and mount a blank cover? I'd prefer surface mount wiring chases if recepticals are needed, over a receptical ya gotta lean over the wet sink to plug and unplug. Maybe I'm picturing the set up wrong. Sounds awful lazy to leave it as is. Jeff
*
Whoever wired my disposal back in the early 60s, which I am replacing, wired it with a switched neutral. This appears to make some sense, since the switch is in a wet location right above the sink.
I have since installed a GFCI in that 2-gang outlet, and was thinking about wiring the new disposal as "load" on the GFCI with a switched hot, which I imagine is the proper way to do it. However, since this outlet and switch are in a wet location, the GFCI often trips. This would be a pain for the disposal. Perhaps the switched neutral is as safe and more convenient. Any thoughts on this?