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#80586 - 04/29/02 01:46 PM Dryer/Range grounding
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
I was browsing some U.S. wiring sites and saw a note on one that the 2002 NEC now prohibits the frame of a range or dryer being grounded to the neutral.

Can't find the site again now, but is this the case? Do all new dryer/range hook-ups now have to be 4 wire?

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#80587 - 04/29/02 02:04 PM Re: Dryer/Range grounding
AndrusT Offline
Member

Registered: 03/14/02
Posts: 24
yup. Changed about a yr ago for us in MI.

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#80588 - 04/29/02 02:24 PM Re: Dryer/Range grounding
Gwz Offline
Member

Registered: 04/29/02
Posts: 199
Read 1999 NEC 250-140.

Read 1996 NEC 250-60.

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#80589 - 04/29/02 02:30 PM Re: Dryer/Range grounding
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Thanks. The grounding of a range/dryer to the neutral is probably the only aspect of American wiring that has struck me as odd and that I dislike.

1999 NEC 250-140, 1996 NEC 250-60. Anyone care to quote these for me please as I don't have copies?

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#80590 - 04/29/02 04:11 PM Re: Dryer/Range grounding
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Paul,
this is from the 2002 .......
latest, greatest...)

250.140 Frames of Ranges and Clothes Dryers.
This section shall apply to existing branch-circuit installations only. New branch-circuit installations shall comply with 250.134 and 250.138. 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; or, except for mobile homes and recreational vehicles, 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.

this is the 'commentary' after it..


Section 250.140(4) applies only to existing branch circuits supplying the appliances specified in this section. The grounded conductor (neutral) is no longer allowed to be used for grounding the metal non–current-carrying parts of the appliances listed in 250.140. Branch circuits installed for new appliance installations are required to provide an equipment grounding conductor for grounding the non-current-carrying parts.
Caution should be exercised to ensure that new appliances connected to an existing branch circuit are properly grounded. An older appliance connected to a new branch circuit must have its 3-wire cord and plug replaced with a 4-conductor cord, with one of those conductors being an equipment grounding conductor. The bonding jumper between the neutral and the frame of the appliance must be removed. If a new appliance is connected to an existing branch circuit without an equipment grounding conductor, where the neutral conductor was previously used for grounding the appliance, a bonding jumper must be installed at the appliance terminal to connect the frame to the neutral.
The grounded circuit conductor of an existing branch circuit is still permitted to be used to ground the frame of an electric range, wall-mounted oven, or counter-mounted cooking unit, provided all four conditions of 250.140 are met. The grounded circuit conductor is also permitted to be used to ground any junction boxes in the circuit supplying the appliance, and a 3-wire pigtail and range receptacle is permitted to be used, even though the circuit to the receptacle contains a separate equipment grounding conductor.
Where service-entrance cable was previously installed, an uninsulated covered neutral conductor was allowed. However, the circuit was required to originate at the service equipment to avoid neutral current from downstream panelboards flowing on metal objects, such as pipes or ducts. Exhibit 250.51 shows an existing installation in which Type SE service-entrance cable was used for ranges, dryers, wall-mounted ovens, and counter-mounted cooking units. Junction boxes in the supply circuit were also permitted to be grounded from the grounded neutral conductor.

i can post more if need be...

[This message has been edited by sparky (edited 04-29-2002).]

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#80591 - 04/30/02 09:24 AM Re: Dryer/Range grounding
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Thanks Steve -- I think that pretty much covers it.

So existing circuits can continue as 3-wire (subject to the listed conditions) but new ones have to be 4-wire with separate ground.

I take it everyone here will be quite happy with the new requirement, yes?

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#80592 - 04/30/02 03:05 PM Re: Dryer/Range grounding
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
 Quote:
I take it everyone here will be quite happy with the new requirement, yes?


well...maybe not the appliance guys, they never know which 'pigtail' to sell.....

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#80593 - 04/30/02 09:07 PM Re: Dryer/Range grounding
caselec Offline
Member

Registered: 04/14/02
Posts: 557
Loc: San Jose, CA
I agree with the new requirement for having separate ground and neutral connections. One problem that I am seeing though is that the ranges and dryers still come from the factory with the neutral bonded to the frame and many people will install the 4 wire cord with out removing the jumper. This is not a problem if the circuit comes from the main service panel but if its coming from a sub panel you will end up with a parallel neutral path for all of the circuits in the sub panel. I guess since most of the ranges and dryers are being installed in existing installations its better to depend on the installer to remove it for a new installation then depend on the installer to install a jumper for an existing installation. Another idea would be for the factory to install 4 wire cords on all ranges and dryers and then sell an adapter to use it on a 3 wire receptacle.
_________________________
Curt Swartz

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#80594 - 05/01/02 09:08 AM Re: Dryer/Range grounding
Trainwire Offline
Member

Registered: 03/15/02
Posts: 364
Loc: Strasburg,PA,USA
Pardon me for the ignorance, but would it be code compliant, that the next time I pull the range out from the wall, I run a seperate, single conductor, green, 10AWG wire from the range to the panel? The range in my house is hard wired , with a looop so you can pull it out from the wall far enough to get at the connections. I would like to put a socket/plug on it the next time my wife wants to clean under it. It might have to be green taped 8awg, come to think of it.

Thanks for your patience.

Trainwire

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