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3 PRONG vs. 4 PRONG OVEN OUTLET?

104K views 17 replies 7 participants last post by  Schrade 
#1 ·
Hey all,

Looking for some advice... i recently had some work done in preperation of a kitchen remodel. The old wire for the oven was left untouched and the electrician assured me it was ok to use. He caped it with a three prong outlet but I've been reading up that the standard for modern oven is 4 prong!? Is this correct or will i have to open up the wall again? He seemed confident that this is fine.

Please advice, just want to make sure i'm ok here?

Much thanks!
 
#2 ·
Hey all,

Looking for some info here, i recently had some work done in preperation of a kitchen remodel. The old wire for the oven was left untouched and the electrician assured me it was ok to use. He caped it with a three prong outlet but I've been reading up that the standard for modern oven is 4 prong!? Is this correct or will i have to open up the wall again? He seemed confident that this is fine.

Please advice, just want to make sure it's ok?

Much thanks!
With a few exceptions its legal... wanna know the exceptions?
 
#4 ·
please...

and what happens when i buy a new oven?
Do i have to outfit it with a diferent cord to fit the 3 prong?

Thanks!
Ranges do not come with cords installed on them, so you just reuse your 3 wire cord. Stubbie has some great pics on the correct bonding procedure.


Here are the exceptions...

250.140 Frames of Ranges and Clothes Dryers
Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes
dryers, and outlet or junction boxes that are part of the circuit for these appliances shall
be grounded in the manner specified by 250.134 or 250.138.
Exception: For existing branch circuit installations only where an equipment grounding
conductor is not present in the outlet or junction box, the frames of electric ranges, wallmounted
ovens, counter-mounted cooking units, clothes dryers, and outlet or junction
boxes that are part of the circuit for these appliances shall be permitted to be grounded
to the grounded circuit conductor if all the following conditions are met.

(1) The supply circuit is 120/240-volt, single-phase, 3-wire; or 208Y/120-volt derived
from a 3-phase, 4-wire, wye-connected system.

(2) The grounded conductor is not smaller than 10 AWG copper or 8 AWG aluminum.

(3) The grounded conductor is insulated, or the grounded conductor is uninsulated and
part of a Type SE service-entrance cable and the branch circuit originates at the
service equipment.

(4) Grounding contacts of receptacles furnished as part of the equipment are bonded to
the equipment.
 
#6 ·
well...

That is a bit over my head but i feel reassured it is exceptable.
He did mention the ground wire and seemed very competent and confident it was safe.

I just want to make sure when I get the new stove I can successfully connect and it's ok to use.

As long as you had an electrican do the work, I would say you have a better than nothing that its correct. :)
 
#8 · (Edited)
Hello Casey

Your new range will likely come configured for a three wire connection but you need to look carefully to be sure of this and carefully read your instructions as to the electrical requirements. You are allowed to reuse an existing 3 wire branch circuit under the conditions Chris posted.

Anyway the instructions will give you specific detail on how to convert the range and how it is configured from the factory...3 wire or 4 wire. If it is 3 wire configured you will simply need to purchase a 3 wire range cord connect it to your stove and plug it in. If it is 4 wire configured you will need to remove the bonding jumper from the neutral terminal on the range terminal block to the metal fram of the range. Manufacturers use different methods for this bonding jumper. Can be a metal strap, or a green and yellow striped wire etc. All this will be explained in the installation instructions. I'll post a few diagrams so you can get a feel as to what you will be looking for and this should help you understand the process.

First diagram is a 3 wire to 4 wire range connection

Second is a 3 wire connection usually how they come from the factory and will simply install a 3 wire range cord and plug into an existing 3 wire receptacle.
 

Attachments

#11 · (Edited)
My problem is reversed there Mr. Stubbie...

My new range already has the 4-prong cord attached, and the outlet is 3-prong. I'm presuming I can pull the 3-prong cord from the old unit, and connect it to my new one...

BUT, which 'terminal' on the new stove is gonna' get left out? (or, do 2 of the terminals get bridged???)

EDIT:
Just found this elsewhere:
The center terminal on the plug, indeed, needs to be connected to the white wire and the red and black wires to the side terminals. You need to connect a ground wire preferably green from someplace on the stove to the grounding connection on the plug. The stove will work just fine without it but if something goes wrong with the internal wiring of the stove, the chassis could become "hot" and the breaker wouldn't trip. Should that happen, you could get shocked with 120 V when you touch the range and something that is grounded at ...(Answered by dlmrgnk)
The grounding connection on the plug = neutral terminal on the 'range terminal block'?
 
#15 · (Edited)
Bumpin' here; post is gettin' buried already...

My problem is reversed there Mr. Stubbie...

My new range already has the 4-prong cord attached, and the outlet is 3-prong. I'm presuming I can pull the 3-prong cord from the old unit, and connect it to my new one...

BUT, which 'terminal' on the new stove is gonna' get left out? (or, do 2 of the terminals get bridged???)

EDIT:
Just found this elsewhere:
The center terminal on the plug, indeed, needs to be connected to the white wire and the red and black wires to the side terminals. You need to connect a ground wire preferably green from someplace on the stove to the grounding connection on the plug. The stove will work just fine without it but if something goes wrong with the internal wiring of the stove, the chassis could become "hot" and the breaker wouldn't trip. Should that happen, you could get shocked with 120 V when you touch the range and something that is grounded at ...(Answered by dlmrgnk)
The grounding connection on the plug = neutral terminal on the 'range terminal block'?

"old post ... AND, info still very..." :wink:
old post but info still very much needed..
:whistling2: Your local grammar nazi @ work yup...
 
#17 ·
Sorry Schrade. You probably should have made a new post. Yours kinda got lost in the noise. The neutral terminal of the stove needs to be connected to the frame when you go to a 3-wire cord. How this is done is dependent on the brand of stove. Sometimes it is a wire that connects from the neutral terminal to a screw, and sometimes it is two wires connected together.
 
#18 · (Edited)
Copy on that - thanks.

I fabbed a strap out of a corner brace, to bridge from the frame where the wire was attached, directly to the neutral terminal. She's toasty now! :yes:



If you're like me, be careful (I'm highly allergic to electricity - gives me the shakes 'n stuff. And I'll share too. Friends are good for keepin' ya' 'grounded - know what I mean?)
 
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