dryer cords

[Anonymous]

Posted by: jack (old forum transfer)
Posted - 06/16/2002 : 00:18:21

can you wire a 4 prong dryer to a 3 prong plug with a 3 wire cord? if not does someone make a 4 to 3 plug wire?

[Anonymous]

Posted by: Wgoodrich
Posted - 06/16/2002 : 01:23:37

I take it you have bought a new dryer with a four wire pigtail and an existing three prong dryer receptacle in your home.

No problem.

Remove the four prong dryer pigtail cord and install a three wire three prong pigtail dryer cord. Then install a jumper in the dryer between the center scew of the terminal block where you neutral wire of your dryer pigtail connects from that center screw install that jumper to the green screw mounted on the metal frame of your dryer. The neutral wire is allowed to be used as a dual purpose wire being both equipment grounding and neutral as one conductor in existing homes with an existing three prong receptacle.

HOpe this helps

Wg

[Anonymous]

Posted by: Jafro
Posted: Thu Jul 11, 2002 1:26 am

You can not put a jumper from the neutral to ground in the appliance!!! By doing this you will be creating what is called circulating ground currents which have been know to burn down homes. This is a dirrect code violation in Canada and the USA.
Spend the few dollars <$30 to buy the proper 4 wire cord and the proper 4 wire female receptacle. install it according to the instructions and you will sleep happy knowing that your family will WAKE UP ALIVE

[Anonymous]

Posted by: Wgoodrich
Posted: Thu Jul 11, 2002 3:18 pm

Welcome Jafro, glad to see you post a reply in an attempt to help and to clarify the requirements of the NEC and the CEC.

I am curious. YOu suggested installing a four wire dryer pigtail to that new dryer and use a 4 prong dryer receptacle if I am reading your reply correctly. If you do this four prong receptacle conversion to an existing three prong dryer receptacle connected to a dryer branch circuit that only has two insulated hot conductors and an insulated grounded conductor but no equipment grounding conductor in that three wire existing dryer branch circuit, where do you plan to connect your equipment grounding conductor of that four wire dryer pigtail that is required to bond the noncurrent carrying metal frame of that dryer?

You would have four connections in the four prong receptacle but only three wires of the existing dryer branch circuit.

What is your plan on bonding that metal dryer frame to an equipment grounding conductor?

If you would, I would appreciate it if you would provide the Code reference numbers of both the CEC and the NEC that you suggested makes what was previously advised
"installing an equipment grounding bonding jumper between the neutral lug of the dryer terminal block to the metal frame of the dryer", so that we can have a reference where you are coming from with the Code violations that you referred to, so that we can validate your claim that this bonding jumper in the dryer between the neutral and the metal frame of an electric dryer being served by an existing three wire dryer branch circuit would be a violation of those two electrical codes.

Thanks

Curious

Wg

[Anonymous]

Posted by: Jafro
Posted: Fri Jul 12, 2002 3:28 pm

First of all let me appologize for not reading the posting correctly. I did not see that the cable had no bonding conductor. Big mistake. I must agree with you on the jumper. Would it be possible to install a seperate bonding conductor back to the water supply from the dryer or better yet replace the cable with a new one.

Jafro

[Anonymous]

Posted by: Wgoodrich
Posted: Fri Jul 12, 2002 5:17 pm

Jafro, no opologies necessary, just remember you missed something in this post so that when I miss something in the next post you can catch me and get me to take a second look. We all miss things. That is why it is so pleasant to see you chime in. Several minds, thoughts and sets of eyes are kind of like watching over each other when we miss something.

I understand your concern about wanting a separate grounding conductor ran back to the panel much like the NEC allows when changing out normall 15 and 20 amp receptacles from two prong to three prong.

However if you will check the following copied section of the 2002 NEC. There is an NEC rule in both the 99 and the 2002 NEC that allows a three wire existing dryer branch circuit to use the neutral and grounding conductor as one conductor but only for existing branch circuits. There is no limitation of using this existing three wire three prong dryer branch circuit on a new or old dryer appliance. Then once you have read this exsting dryer branch circuit rule check out any new electric dryer and the manufacturer's instructions tell you do install the bonding jumper from the neutral screw of the dryer terminal block to the metal frame of the dryer when using an existing three wire dryer branch circuit. Then 110.3.B tells us that we must wire by the manufacturer's instructions and recommendations.

Copied section of the NEC 2002 for existing three wire dryer branch circuits.

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.

COPIED SECTION OF THE 2002 NEC HANDBOOK 250.140

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.


Jafro, one special note; Existing ranges and ovens also are incluede in this existing rule as well as electric dryers that apply whether new or old appliance as long as the appliance is served by an existing three wire branch circuit.

Hope this helps

Wg

[Anonymous]

Posted by: Jafro
Posted: Sat Jul 13, 2002 3:17 pm

WG:I must with draw my last reply. After thinking about it and checking the code I have found our code rules that do not allow installing the jumper.
CEC Definition of Receptacle:
Quote: means one or more female contact devices on the same yoke, installed at an outlet for the connection of one or more attachment plugs

CEC Rule:26-700 (

CEC quote:
( Where grounding type receptacles are used in existing installations to replace the ungrounded type, the grounding terminal shall be effectively bonded to ground, and one of the following methods shall be permitted to be used:
(a) By connection to a metal raceway or cable sheath that is bonded to ground;
(b) By connection to a system ground by means of a separate bonding conductor;
(c) By bonding to an adjacent grounded metal cold water pipe.

(9) Notwithstanding subrule ( at existing outlets in residential occupancies where a grounding means does not exist in the receptacle enclosure, grounding type receptacles without a bonding conductor shall be permitted to be installed provided each receptacle is:
(a) Protected by a ground fault circuit interrupter of a Class A type that is an integral part of this receptacle; or
(b) Supplied from a receptacle containing a ground fault circuit interrupter of a Class A type ; or
(c) supplied from a circuit protected by a grouind fault circuit interrupter of a Class A type.

Jafro

[Anonymous]

Posted by: Wgoodrich
Posted: Sat Jul 13, 2002 6:11 pm

Jafro, does the CEC [Canadian Electrical Code] have a rule in it that addresses existing dryers and ranged like the copied section that I provide in the NEC? Just curious. The CEC is one code that I am weak on.

The NEC has made a concerted effort to address existing wiring situation such as the Code copied section that I provided. Just wondering if the CEC also have attempted to address existing for say reduced height of headroom for breaker panels or the existing range etc.

Curious

Wg

[Anonymous]

Posted by: gordgraham@shaw.ca
Posted: Mon Jul 15, 2002 5:13 pm

Warrren: The CEC ( Canadian Electrical Code) does not differentiate between between old or new equipment such as dryers or washers. Section 0 (OBJECT)
Quote:
The object of this code is to establish safe standards for the installation and maintenance of electruical equipment. In its preparation, consideration has been given to the prevention of fire and shock hazards, as well as proper maintenance and operation.
The only reference to panels is in section 26-704
Quote:
(1) Panel boards shall not be located in coal bins,cloth closets,bathroom,stairways,high ambient rooms,dangerous or hazardous locations,nor in any similiar undesirable locations.
(2) Panelboards in dwelling units shall be installed as high as possible with no overcurrent device operating handle being more than 1.7 meters ( 5 ft 7 in ) above the finished floor area.

Jafro

[Anonymous]

Posted by: Wgoodrich
Posted: Mon Jul 15, 2002 6:42 pm

gordgraham, what does the CEC say concerning houses that have been wired in previous codes. {existing}.

Does every house have to be rewired every time the CEC is revised to meet current code?

What this post pertains to is an existing dryer receptacle where a new dryer was purchased to replace the old dryer.

In the USA the manufacturer provides means of adapting a new range to accept an old three wire existing dryer branch circuit.

Are you saying that a new dryer in the CEC requires a new four wire branch circuit forbidding the use of the existing three wire branch circuit?

Curious

Wg

[Anonymous]

Posted by: gordgraham@shaw.ca
Posted: Mon Jul 15, 2002 11:14 pm

Hello Warren:
You do not have to re-wire your home every time the code changes. If that was the case I would be retired in Florida, California or maybe Indianna. The CEC does not allow adaptors.
Electric Heating and Cooking Appliances:
Section 26 Subrule 744 (3)
An electric cloths dryer having an input in excess of 1500 watts at 115 volts but not exceeding 30 amps, and used in a dwelling unit,shall be cord-connected by means of a cord and attachment plug of CSA Configuration 14-30P(plug) to the receptacle referred to in subrule (2)
Subrule 2 refers to the receptacle 14-30R(receptacle)
This receptacle and plug are 30 amp 4 pole non locking type
If you purchase and install a new dryer (say in a 40 year old home)then you must upgrade the branch circuit wiring to the present day code.

Gord

[Anonymous]

Posted by: Woodrich
Posted: Tue Jul 16, 2002 2:43 pm

Looks like there are some very major differences in the CEC [Canadian electrical Code] versus the NEC. National electrical Code] {USA}. The NEC addresses existing branch circuits for dryers and the manufacturer provides instructions to allow a new dryer to be connected to an existing branch circuit. YOu Canadian Code obviously does not allow this but requires a new branch circuit to be installed.

Wonder how many in both country have been either confused or have cheated concerning the NEC and CEC on this subject. There may never be an answer to that questoin but suspect both counctries have had some experience along that line concering electric dryers and ranges.

Thanks for the CEC update

Wg

[Anonymous]

Posted by: Jared
Posted: Sat Jul 20, 2002 8:06 pm

Thank you in advance for your time!
My quest begins with questions about an informal advisory in regards to the proper amperage for a circuit trip

residential,sigle dwelling,cloths dryer supply line.
Currently on a 40A
advised to reduce to 30A.
(To be consistant with the message thread: site unseen I believe it to be a 3 conductor scenerio).
My interest is:
what does the NEC recomend for amperage rating of the breaker?

what are some of the more common differences to this recomendation in local municipalities?

where would I find technical specifications regarding electrical/thermal trip speeds/sensitivities, *if this is subject to the requirements for standard residential applications?

And finaly, what are the advants or disadvantages comparing electromagnetic to electromechanical(thermal?) type breakers?

Thank you again, Jared

Back to top

[Anonymous]

Posted by: Wgoodrich
Posted: Sun Jul 21, 2002 12:41 pm

You said;
Thank you in advance for your time!
My quest begins with questions about an informal advisory in regards to the proper amperage for a circuit trip

residential,sigle dwelling,cloths dryer supply line.
Currently on a 40A
advised to reduce to 30A.

REPLY;
YOu have sound advice. If you will check minimum ampacity required for your branch circuit you should find in NEC Article 220.18 which states that clothes dryers if with electric heat must be rated a minimum of 5000 volt amps which would equal 25 amps rounded up to the nearest amp rated breaker listed in 240.6 of that NEC. Then it goes further saying that you must check you name plate rating in amps found on you name plate and must be rated a minimum of that size branch circuit that is equal to the load rating of that dryer. Then if you check the maximum amp rating on your dryer's name plate or you manufacturer's recommendations you should find 30 amps is maximum that your dryer is rated to accept. 110.3.B of the NEC requires that you follow the manufacutrer's recommendations. If you check I suspect you will find that your manufacuter's recommendation says maximum branch circuit rating of 30 amps.
COPIED SECTION OF NEC 2002;
220.18 Electric Clothes Dryers — Dwelling Unit(s).
The load for household electric clothes dryers in a dwelling unit(s) shall be 5000 watts (volt-amperes) or the nameplate rating, whichever is larger


YOU SAID;
(To be consistant with the message thread: site unseen I believe it to be a 3 conductor scenerio).
My interest is:
what does the NEC recomend for amperage rating of the breaker?

REPLY;
If you have an existing three wire dryer branch circuit that is 10 awg on a thirty amp breaker with a black red and white wire in the cable or a black red and bare wire if in an service entrance cable then you have a rule in the NEC 2002 that addressed existing three wire branch circuits. This rule tells us that you may continue to use this existing three wire circuit whether new or old. If you are using an existing three wire cable as discribed above then you must have or install a bonding jumper inside you electric dryer joining the center neutral screw of the terminal block where your pigtail connect installing a jumper to the metal frame of the dryer whether new or older style dryer. If a new four wire branch circuit is installed meeting the requirements of a new installation then the jumper joining hte metal case of that dryer to the center neutral screw of the terminal block inside you dryer where you cord is connected to the dryer whether this new four wire branch circuit serves a new or old dryer.

YOU SAID;
what are some of the more common differences to this recomendation in local municipalities?

REPLY;

Be careful on this existing rule if you are under the rules of the CEC serving Canada, it is my understanding that this rule approaching existing range or dryer three wire branch circuits being allowed is not in that Canadian Electrical Code.

You should check you state or local jurisdictions and electrical inspector no matter what kind of electrical project is being done. Many variations exist concerning local and State rules, way too many to list. Only your local AHJ can answer what special rules or revisions to rules exist in your locality.


YOU SAID;
where would I find technical specifications regarding electrical/thermal trip speeds/sensitivities, *if this is subject to the requirements for standard residential applications?

REPLY;
You need to check with you local AHJ or serving Utility company to confirm you interupting ratings required by them. The interupting rating changes per intended usage and type of service compared to the requirements of your serving Utility company.

YOU SAID;
And finaly, what are the advants or disadvantages comparing electromagnetic to electromechanical(thermal?) type breakers?

REPLY;

Dwelling use what is called inverse time breakers which creates a curve in both operations that you mentioned. Inverse time breakers serving dwellings if approved for use in a dwelling operate both magnetically with interupting ratings due to faulted or short circuits on the circuit served and mechanical with thermal build up limits due to amps pulled on the circuit.

Hope this helps

Wg