4wire dryer connections

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geochurchi

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Concord,NH
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Retired electrician
Hi All, new dryers, ranges now come equipped with 4 wire cords,what does the NEC require if the existing receptacle is a 3wire?
Geo
 
Actually your statement is backwards.
New construction as of the '90's required the circuit to ranges and dryers be 4 wire and that if you had an existing receptacle that was 3wire in an existing dwelling it was grandfathered so to speak. All ranges and dryers have a ground bonding strip at the connection block that either needs to be removed if using the 4 wire cord or be left in in the case of connecting to existing 3wire outlet.(see instructions or label pertaining to this)
Something tells me that 4 wire connections may be required now for all installations, have to look it up.
 
3-wire is acceptable for existing installations, installations done since the adoption of the 1996 NEC are required to be 4-wire, it was a change long overdue.
 
mjf said:
You are not required to upgrade the premises wiring. I would remove the provided cord and install a 3 prong cord. follow the manufacturers instructions to bond the neutral and the ground on the appliance.
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If the appliance is "moved", requiring the removal of the three wire receptacle, you have to go to the four wire receptacle and, of course, change the cable and remove the jumper.
 
Sierrasparky said:
What about if originally fed from a sub panel?
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It's compliant from a sub panel if the neutral is insulated. That would mean 10-3 NM.

I change a couple of dryer recpts a year, original is a three wire recpt but with 10-3 ran and the bare is not used. Swap out to a four wire recpt and I'm all done........the egc is all ready landed in the panel most times.
 
I've never seen a dryer or range come with a cord. I know they don't ship with them.
An appliance store or "big box" store may send one with the delivery but if you look at your invoice it will be charged extra for. They usually (sometimes) will ask if you need a cord and how many wires but they just don't automatically come with one.

Since the 3-wire is still acceptable they have no way of knowing what the customer has for wiring, 3 or 4-wire.
 
Little Bill said:
I've never seen a dryer or range come with a cord. I know they don't ship with them.
An appliance store or "big box" store may send one with the delivery but if you look at your invoice it will be charged extra for. They usually (sometimes) will ask if you need a cord and how many wires but they just don't automatically come with one.

Since the 3-wire is still acceptable they have no way of knowing what the customer has for wiring, 3 or 4-wire.
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That is what I am seeing. If the seller sends out someone to deliver and install it - they just put on whatever cord matches the receptacle present - and usually have no clue if it is code compliant as is, but IMO that is what they should do anyway - they are not installing premises wiring - if it is wrong then it is the fault of the installer of premises wiring.
 
norcal said:
3-wire is acceptable for existing installations, installations done since the adoption of the 1996 NEC are required to be 4-wire, it was a change long overdue.
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Did 3-wire dryer and oven connections actually ever create problems that 4-wire resolves? Fire, shock-hazard, ground loops? I've always wondered if there was actual hard evidence for the code change.
 
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edlee said:
Did 3-wire dryer and oven connections actually ever create problems that 4-wire resolves? Fire, shock-hazard, ground loops? I've always wondered if there was actual hard evidence for the code change.
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Funny you should ask this question. I really can't answer your question but I can share a story.

Last month I was called to a home to check out the new 240v Dryer that was delivered earlier in the day. Dryer was making quite a noise when turned on and it would run for about 15 - 20 sec. then shut off.

As I was pulling the Dryer out to get behind to open the wiring compartment I noticed a big scorch mark on the Dryer cabinet and on the Washer right next to it. I had unpluged the cord of course, 3 wire set up.

As I was checking the cord connections the HO told me the Installer had received a real bad shock when pushing the Dryer into place.

I found that the Installer had put one of the ungrounded leads on the center terminal, and of course the jumper was connected to the Dryer cabinet.

Easy fix.
 
1793 said:
I found that the Installer had put one of the ungrounded leads on the center terminal, and of course the jumper was connected to the Dryer cabinet.

Easy fix.
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But any wiring method is dangerous when done incorrectly so I don't see that proving a need for the code change.
 
iwire said:
But any wiring method is dangerous when done incorrectly so I don't see that proving a need for the code change.
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I think I understand your statement but don't most code changes come about to make electrical installations safer and somewhat idiot proof, with regards to personal injury?
 
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kwired said:
That is what I am seeing. If the seller sends out someone to deliver and install it - they just put on whatever cord matches the receptacle present - and usually have no clue if it is code compliant as is, but IMO that is what they should do anyway - they are not installing premises wiring - if it is wrong then it is the fault of the installer of premises wiring.
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This is correct but I'd like to add to this - the vast majority of appliance retailers are out there to sell appliances and have no clue as to what is required to be code compliant. If a HO tells them that they have a 3-prong receptacle, they'll ship a 3-prong cord, make the cord connection to the unit (H-N-H) and install the dryer. However, if the HO tells them they have a 4-prong receptacle, they'll ship a 4-wire cord, hook it up (H-N-H-G) but forget to remove the metal strap on the neutral terminal thereby bonding the neutral to the frame of the dryer. At that point, (other than the correct plug-receptacle fit) there's no point in having a 4-wire circuit, receptacle, cord and plug.
 
goldstar said:
This is correct but I'd like to add to this - the vast majority of appliance retailers are out there to sell appliances and have no clue as to what is required to be code compliant. If a HO tells them that they have a 3-prong receptacle, they'll ship a 3-prong cord, make the cord connection to the unit (H-N-H) and install the dryer. However, if the HO tells them they have a 4-prong receptacle, they'll ship a 4-wire cord, hook it up (H-N-H-G) but forget to remove the metal strap on the neutral terminal thereby bonding the neutral to the frame of the dryer. At that point, (other than the correct plug-receptacle fit) there's no point in having a 4-wire circuit, receptacle, cord and plug.
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That is correct, how do you propose to solve that problem? Even appliance installers (who really have little or no electrical know-how) will not remove the bonding jumper when they install a 4 wire cord. This can effect an entire panel and related loads supplied from a four wire feeder effectively making it a three wire feeder.

I once had a service call in a mobile/manufactured home they pulled out the dryer when they were doing some painting and when they unplugged it they heard popping sounds, smoke was released from some electronics in different items around the house. The feeder neutral to the house had been lost - the dryer had a 4 wire receptacle/cord but the bonding strap in the dryer had not been removed - so the entire home neutral was depending on the EGC, the bonding strap in the dryer and the dryer plug/receptacle for continuity.
 
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