ECN Forum
Posted By: aldav53 Oven hook-up (3 - 4wire) - 09/19/06 09:18 PM
This is old subject, but still can't figure out why on a new oven ckt, the manufacturer says you can use a 3 or 4 wire ckt. The oven controls must be 120v, which would mean you'd be tying the neutral to the ground at the oven (cause they are 4 wire) and the ground would then be part of the current carrying path back to the panel on a 3 wire ckt. Is this code for new ovens?
Posted By: iwire Re: Oven hook-up (3 - 4wire) - 09/19/06 09:41 PM
The code used to allow us to install 3 wire range and dyer outlets in certain locations.

Quote
which would mean you'd be tying the neutral to the ground at the oven

No the code did not allow that, what they did allow was using the neutral as the grounding means.

You say 'hey thats the same thing'. It's close to the same thing but it requires that the conductor be insulated.

Now the code will not let us install 3 wire range and dryer outlets. But existing ones can remain so when the customer gets a new range they need to buy a power cord that fits the outlet they have and they have to either bond or un-bond the neutral to frame.
Posted By: aldav53 Re: Oven hook-up (3 - 4wire) - 09/19/06 09:50 PM
Which one would it be, bond or not bond the neutral to the frame.
Thanks,
Posted By: iwire Re: Oven hook-up (3 - 4wire) - 09/19/06 10:02 PM
If the outlet is 3 wire you must bond the neutral to the frame of the appliance

This is done by a jumper at the point on the oven where the supply cord connects.

If it is a 4 wire outlet you want to make sure to lift the bond.
Posted By: Celtic Re: Oven hook-up (3 - 4wire) - 09/20/06 12:48 AM
Here's a tangent to this...

We recieved a delivery of electric ranges...the order stipulated that the ranges have the cords attached...the ranges have a 4-wire cord attached...the range itself has a the jumper still installed between N-G.
These ranges are being installed in new construction.

Who would say is responsible for checking that connection?
- The Appliance Co. where they were ordered from
- The GC that ordered them
- The EC that installs them
- Check the contract

[This message has been edited by Celtic (edited 09-19-2006).]
Posted By: ShockMe77 Re: Oven hook-up (3 - 4wire) - 09/20/06 12:54 AM
^^

I would say it's the responsibility of the EC.

Why?

Because you are the professional electrician who knows the importance of when to bond and when not to. And if we don't do it, who will? I like to think of as having some integrity.

That's my opinion. Perhaps the legality of it is something different all together.

[This message has been edited by ShockMe77 (edited 09-19-2006).]
Posted By: HLCbuild Re: Oven hook-up (3 - 4wire) - 09/20/06 01:54 AM
Cord or no cord, I'll bet there are installation instructions that tell you if you are using a 4-wire configuration then you must remove the jumper. So the installer is responsible to follow the manufacturers instructions.
Posted By: Celtic Re: Oven hook-up (3 - 4wire) - 09/20/06 03:05 AM
The installer being the EC who installs the appliance or the installer who installed the cord?
Posted By: ShockMe77 Re: Oven hook-up (3 - 4wire) - 09/20/06 03:38 AM
The electrical contractor.

If the cord comes with the appliance (wich it seldom does), the installer at the factory has NO IDEA if the range is going into a new home or into an existing home as a replacement. My experience has been to bring both type cords with me to save on those pesky trips to the suppy house.

Speaking of the supply house, I have to get to mine in about 7 hours so time to get some sleep! [Linked Image]
Posted By: gfretwell Re: Oven hook-up (3 - 4wire) - 09/20/06 03:56 AM
They do ship with cords attached if you order them that way. I can't imagine a builder ever ordering anything but 4 wire corded appliances. There should never be a 3 wire range or dryer plug in new construction. If the jumper is installed it is a factory problem.
Posted By: aldav53 Re: Oven hook-up (3 - 4wire) - 09/20/06 05:32 AM
Its a double convection oven and a has a pigtail with 3 - #10 conductors and a ground. So will go a 10-3 NM 30a ckt new ckt.

But... If there was an old 10-2 ckt already there, I would have to tie the neutral and ground together from the oven at the junction, correct?
Posted By: NORCAL Re: Oven hook-up (3 - 4wire) - 09/20/06 06:02 AM
If 10/2 you need to repull feed, EGC not suitable for a neutral.
Posted By: e57 Re: Oven hook-up (3 - 4wire) - 09/20/06 07:10 AM
Celtic, I would say it was between who ordered or recieved the order of the ranges, but clearly the persons who installed the cord would be the responcable party for checking that neutral ground bond. They installed the cord, and being as such, any HO or GC could install it themselves and be totally unaware. They keep shipping them 3-wire as replacement units. When what they should do is ship them as 4-wire and note if there is a problem with the cord not matching to call an electrician. Or devise a detachable choice of cords, and a special mating that has the bond on the 3-wire one, or no bond on the 4-wire one.

aldav53, (And NORCAL)
The 4-wire code is only for New Construction.... You might still be able to use it? If, "the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment." See 250.140, all 4 conditions in it need to be met.

aldav53, I'm questioning your wording on your last post in my head though...

"Its a double convection oven and a has a pigtail with 3 - #10 conductors and a ground. So will go a [/i]10-3 NM[/i] 30a ckt new ckt."

Have you checked the name-plate kW of this "double convection oven"? Just because it has #10 conductors in the pigtail, (which may be aspestos appliance wire rated for high temp) doesn't mean it is a 30A circuit. Odds are that it is a 40-50A unit! Often appliances are wired with much smaller whips in high temp wire insulation rated for a lot more ampperage that thier building/premisis wiring counterparts.
Posted By: renosteinke Re: Oven hook-up (3 - 4wire) - 09/20/06 02:01 PM
I don't do houses hardly at all... but...

The last one I did (30 months ago) had the electrical work completed long before the appliances were delivered. The appliances were unloaded, moved into place, and plugged in by the appliance guy.

As luck would have it, I was there that day. While these particular appliances had cords that matched the receptacles I had installed, other comments by the appliance guy made clear two things:
-He considered himself to be some sort of electrical guru; and,
-He had no idea what he was talking about.


I see the EC as only being expected to put in the receptacle correctly. What's inside the appliance isn't his concern.
Folks want the stuff hard wired, well, that changes things. Then, I get to put in a disconnect as well.
Posted By: NORCAL Re: Oven hook-up (3 - 4wire) - 09/21/06 12:32 AM
E57, my comment was directed at 10/2 NM (I know it was not mentioned as nonmetallic sheathed cable)as do not know of any SE cable below 6 or 8 AWG and I still say the uninsulated conductor of a NM cable should not be used as a current carrying conductor.
Posted By: trobb Re: Oven hook-up (3 - 4wire) - 09/21/06 04:26 AM
NORCAL-
I agree, I'd hate to be working in a supposedly dead box, bump the ground, and get a shock.
Posted By: e57 Re: Oven hook-up (3 - 4wire) - 09/21/06 06:05 AM
NORCAL, was meant as no afront..... And neither of us can see it from here. [Linked Image] I just love finding thos quirky little exception... One thing I don't understand about that particular code is that SE from a main panel would be OK, (w/ an uninsulated ground) but a simular circuit in NM (w/ an uninsulated ground) would not?
Posted By: NORCAL Re: Oven hook-up (3 - 4wire) - 09/21/06 12:20 PM
None taken. [Linked Image]
Posted By: pauluk Re: Oven hook-up (3 - 4wire) - 09/21/06 04:06 PM
Who's responsible?

This isn't an issue we have over here, but speaking for myself, if I were the one installing the cord I would make sure that the jumper is present if I was fitting a 3-wire cord or absent if a 4-wire.

Judging by the number of times this comes up however, I think if I were the EC actually installing the range I would always want to check the connections no matter what type of cord had been pre-fitted.
Posted By: mikesh Re: Oven hook-up (3 - 4wire) - 09/21/06 04:30 PM
In the great white north we have never had 3 wire exceptions for any appliances so you would think it is a non issue. We do however have imigration and some US citizens bring their appliances here. If an electricain is involved we usually change the cord to a 4 wire and ensure the neutral is isolated from the frame. It is when the newly landed appliance owner believes he is smarter than a local electrician that we see bootleg bonding.
Actually with pressure from insurance companies mounting to rewire old houses I am seeing more bootleg grounds in an attempt to concele the presence of K & T wiring. Ocationally they bootleg the hot.
Posted By: Rewired Re: Oven hook-up (3 - 4wire) - 09/23/06 01:29 PM
My 2-cents: it should be the responsibility of the manufacturer to ensure the bonding jumper is installed OR ommitted depending on what cord is installed, but for safety and all out good practice, the EC should double check the appliance(s) supplied.. A couple seconds with a continuity tester never hurt anyone. [Linked Image]

A.D
Posted By: cavie Re: Oven hook-up (3 - 4wire) - 09/23/06 09:02 PM
In new construction, the EC is responsible. Doesn't matter how ordered it. Doesen't matter who installed it. Jonnie's 3 rd cousin once removed might have installed it. Doesen't matter if the plumber install the cord on the dishwasher, The EC of record is responcible for all electric work under that permit. Same goes for bonding the pool steel. I get electricans all the time tell me, "the pool guys did". I don't care who you let do it, it falls under the EC's license.
Posted By: iwire Re: Oven hook-up (3 - 4wire) - 09/23/06 09:15 PM
No way.

The company I work for is not responsible for actions of another contractor or homeowner.

Many of our jobs have multiple ECs with multiple permits I am not responsible for their portion anymore than they are responsible for mine.
Posted By: aldav53 Re: Oven hook-up (3 - 4wire) - 09/24/06 02:35 AM
e57,
The plate doesn't really tell you, it just has the Kilowatt rating for 2 different sizes, 5k and below is #10, and 7k is #8 wire.
The wire writing on the #10 pigtail says 10 AWG AWM 3173 125c XLPE.
This 125 degree centigrade #10 wire need 30 amp wire or 40 amp wire.
There is a energy tag that says 390KW max,(which would be #10 wire) so it sounds like #10-3 NM wire would work, unless the insulation rating on the pigtail. means its good for 40 amps.
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