4-wire required for dryers and ranges?

[ssandoval]

Gentlemen,

I am having a disagreement with one of our contractors right now; he disagrees that 4-wire receptacles are required for 208-120v ranges and dryers and says that only applies to residential installs. I have referred him to sec. 250.140. To me this section is pretty straightforward. I know that dryers and ranges were required to have a neutral starting with the '96 NEC code cycle. He doesn't see it this way. Any thoughts or supporting code references please?

 

[iwire]

As you said the section is very clear, I think you're only hope is to smack him on the head with the code book.

 

[jumper]

As you said the section is very clear, I think you're only hope is to smack him on the head with the code book.

And use a hard bound edition if possible.

 

[iwire]

And use a hard bound edition if possible.

Perfect time to use the hardcover handbook.

 

[winnie]

If the dryer or range being installed is a straight 208V load (and not a 120/208V load as suggested by the original poster), then I'd suggest looking through this recent thread: http://forums.mikeholt.com/showthread.php?t=120280&highlight=neutral

IMHO you cannot share ground and neutral in a new installation, but you are not required to run a neutral if the load doesn't need it.

-Jon

 

[ssandoval]

If the dryer or range being installed is a straight 208V load (and not a 120/208V load as suggested by the original poster), then I'd suggest looking through this recent thread: http://forums.mikeholt.com/showthread.php?t=120280&highlight=neutral

IMHO you cannot share ground and neutral in a new installation, but you are not required to run a neutral if the load doesn't need it.

-Jon

That thread has some excellent info. Looks like I was on track with the reference to 250.140 and I'll throw in 250.142 (B). Thanks to all but keep'em coming.

 

[btharmy]

Gentlemen,

I am having a disagreement with one of our contractors right now; he disagrees that 4-wire receptacles are required for 208-120v ranges and dryers and says that only applies to residential installs. QUOTE]

If the 208-120 is in fact the situation, then yes, you need a neutral to have 120v. I noticed you said 208 which leads me to believe this is a commercial install. There may be equipment that is rated (as stated earlier) at 208v. singel phase. In this case only 3-wire would be required (2 hots and an equipment ground. No 120 = no need for a neutral. Of course the electrical requirements for any piece of utilization equipment should be provided by the manufacturer. The point is that the neutral (grounded conductor) can not be connected to the dryer chassis and other metal parts unless it is an existing install and specific requirements are met.

 

[Jim W in Tampa]

The outlet must be 4 wire having 2 hots and neutral plus ground. Now if your dryer or range does not need the neutral that is fine you simply to not connect it. But it must be ran to the outlet. Existing can remain if was legal at time of install.
208 / 120 might be apartment building

 

[shepelec]

The outlet must be 4 wire having 2 hots and neutral plus ground. Now if your dryer or range does not need the neutral that is fine you simply to not connect it. But it must be ran to the outlet. Existing can remain if was legal at time of install.
208 / 120 might be apartment building

Where does it say you must run it even if you don't use it?

 

[Jim W in Tampa]

OK here is what i see as problem. Your putting in a standard range 50 amp receptacle. If you use the 3 prong it will have a neutral so you have violation as you need a grounding conductor. If you use a 4 prong you will have the grounding and neutral. Now either you run 4 wires or you can not install that receptacle. 250.140 does not directly say you must have a neutral ,it does say you need a grounding. Now when the inspector sees your kitchen he will want either an outlet 120 volt for gas ignitor or 4 prong receptacle.
I ran into this about 8 years ago with a cook top. I ran 10-3 w/g to the junction box under counter. On final cook top arrives and was 240 volt no 120. Inspector would not shut up till i ran him a neutral thru the whip and a wire nut capping it off. Yes he was wrong but this was a 3 mil home and we needed it passed.
So bottom line here is if your going to use a range receptacle you will be running a neutral.
Direct wire it then i say no if not needed but your screwing the customer if they ever change the range or dryer.

 

[shepelec]

If the range is 240v only you could install a 6-50 outlet. You do not have to install a "range" outlet. Just be sure to supply the proper pigtail for the outlet installed. Of course this would work in a rental unit, where the landlord controls the appliances.

 

[bullheimer]

i looked very hard at this on my last job. i had to install a 15A 208V three prong outlet for abrand new oven in a motel's common area. NOTHING i read in the code book said i could get away with a three prong plug.

However, the oven came from the factory with three prong plug and it was not removable. at least not by me, no way. (i assume that the bulbs and timers and everything else in there was 208.) in any event, i only ran 12/2 to the outlet and it passed inspection! i fully expected to have to go back and replace the 12/2 with 12/3 for free.

there are mentions to ranges being in residences, but there are no exceptions for commercial installs that i could find. the article in 250 made it very clear because it talks about any kind of equipment.

however, i think the overriding issue in my case is, that around here EVERYTHING has to be installed according to the manufacturers instructions #1.

 

[eprice]

i looked very hard at this on my last job. i had to install a 15A 208V three prong outlet for abrand new oven in a motel's common area. NOTHING i read in the code book said i could get away with a three prong plug.

However, the oven came from the factory with three prong plug and it was not removable. at least not by me, no way. (i assume that the bulbs and timers and everything else in there was 208.) in any event, i only ran 12/2 to the outlet and it passed inspection! i fully expected to have to go back and replace the 12/2 with 12/3 for free.

there are mentions to ranges being in residences, but there are no exceptions for commercial installs that i could find. the article in 250 made it very clear because it talks about any kind of equipment.

however, i think the overriding issue in my case is, that around here EVERYTHING has to be installed according to the manufacturers instructions #1.

There are two issues here that often seem to get confused. 250.140 says nothing about whether you need a 3 prong outlet or a 4 prong outlet. It only says that you need to connect the frame to an equipment grounding conductor. With most ovens, doing so will require a 4 prong outlet. However there is nothing in the code that I am aware of that requires you to supply a neutral if the equipment doesn't need a neutral. If your oven doesn't need a neutral then I see no code reason that you can't supply it with a 3 prong outlet.

You may be painting your customer into a corner if you don't supply a neutral, because a future replacement oven may need a neutral, but that is a design question, not a code question.