Three prong plug body on two conductor cord.

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elf friend

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Is there any where in the NEC that says you cannot put a three prong plug body on a two conductor cable. Another electrician and I disagree. I say no since this would give the impression of a grounded piece of equipment (a hand drill, saws all, or similar piece of equipment) and the other electrician says it doesnt matter since the drill is double insulated. I looked under the OSHA and there it says the replacement cord/plug has to be done to the manufactors aproved way.
 
elf friend said:
Is there any where in the NEC that says you cannot put a three prong plug body on a two conductor cable. Another electrician and I disagree. I say no since this would give the impression of a grounded piece of equipment (a hand drill, saws all, or similar piece of equipment) and the other electrician says it doesnt matter since the drill is double insulated. I looked under the OSHA and there it says the replacement cord/plug has to be done to the manufactors aproved way.
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406.10 Grounding-Type Receptacles, Adapters, Cord Connectors, and Attachment Plugs.
(A) Grounding Poles. Grounding-type receptacles, cord connectors, and attachment plugs shall be provided with one fixed grounding pole in addition to the circuit poles. The grounding contacting pole of grounding-type plug-in ground-fault circuit interrupters shall be permitted to be of the movable, self-restoring type on circuits operating at not over 150 volts between any two conductors or any conductor and ground.
(B) Grounding-Pole Identification. Grounding-type receptacles, adapters, cord connections, and attachment plugs shall have a means for connection of an equipment grounding conductor to the grounding pole.
A terminal for connection to the grounding pole shall be designated by one of the following:

  1. A green-colored hexagonal-headed or -shaped terminal screw or nut, not readily removable.
  2. A green-colored pressure wire connector body (a wire barrel).
  3. A similar green-colored connection device, in the case of adapters. The grounding terminal of a grounding adapter shall be a green-colored rigid ear, lug, or similar device. The equipment grounding connection shall be so designed that it cannot make contact with current-carrying parts of the receptacle, adapter, or attachment plug. The adapter shall be polarized.
  4. If the terminal for the equipment grounding conductor is not visible, the conductor entrance hole shall be marked with the word green or ground, the letters G or GR, a grounding symbol, or otherwise identified by a distinctive green color. If the terminal for the equipment grounding conductor is readily removable, the area adjacent to the terminal shall be similarly marked.
Informational Note: See Informational Note Figure 406.10(B)(4).
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nfpa.nec.2011_277_01.jpg

Informational Note Figure 406.10(B)(4) One Example of a Symbol Used to Identify the Termination Point for an Equipment Grounding Conductor.
(C) Grounding Terminal Use. A grounding terminal shall not be used for purposes other than grounding.
(D) Grounding-Pole Requirements. Grounding-type attachment plugs and mating cord connectors and receptacles shall be designed such that the equipment grounding connection is made before the current-carrying connections. Grounding-type devices shall be so designed that grounding poles of attachment plugs cannot be brought into contact with current-carrying parts of receptacles or cord connectors.
(E) Use. Grounding-type attachment plugs shall be used only with a cord having an equipment grounding conductor.
Informational Note: See 200.10(B) for identification of grounded conductor terminals.

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Gregg Harris said:
406.10 Grounding-Type Receptacles, Adapters, Cord Connectors, and Attachment Plugs.
(A) Grounding Poles. Grounding-type receptacles, cord connectors, and attachment plugs shall be provided with one fixed grounding pole in addition to the circuit poles. The grounding contacting pole of grounding-type plug-in ground-fault circuit interrupters shall be permitted to be of the movable, self-restoring type on circuits operating at not over 150 volts between any two conductors or any conductor and ground.
(B) Grounding-Pole Identification. Grounding-type receptacles, adapters, cord connections, and attachment plugs shall have a means for connection of an equipment grounding conductor to the grounding pole.
A terminal for connection to the grounding pole shall be designated by one of the following:
  1. A green-colored hexagonal-headed or -shaped terminal screw or nut, not readily removable.
  2. A green-colored pressure wire connector body (a wire barrel).
  3. A similar green-colored connection device, in the case of adapters. The grounding terminal of a grounding adapter shall be a green-colored rigid ear, lug, or similar device. The equipment grounding connection shall be so designed that it cannot make contact with current-carrying parts of the receptacle, adapter, or attachment plug. The adapter shall be polarized.
  4. If the terminal for the equipment grounding conductor is not visible, the conductor entrance hole shall be marked with the word green or ground, the letters G or GR, a grounding symbol, or otherwise identified by a distinctive green color. If the terminal for the equipment grounding conductor is readily removable, the area adjacent to the terminal shall be similarly marked.
Informational Note: See Informational Note Figure 406.10(B)(4).
​
nfpa.nec.2011_277_01.jpg

Informational Note Figure 406.10(B)(4) One Example of a Symbol Used to Identify the Termination Point for an Equipment Grounding Conductor.
(C) Grounding Terminal Use. A grounding terminal shall not be used for purposes other than grounding.
(D) Grounding-Pole Requirements. Grounding-type attachment plugs and mating cord connectors and receptacles shall be designed such that the equipment grounding connection is made before the current-carrying connections. Grounding-type devices shall be so designed that grounding poles of attachment plugs cannot be brought into contact with current-carrying parts of receptacles or cord connectors.
(E) Use. Grounding-type attachment plugs shall be used only with a cord having an equipment grounding conductor.
Informational Note: See 200.10(B) for identification of grounded conductor terminals.

​
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Looks like that is the correct answer.

I have used grounding attachment plugs on cords with no equipment grounding conductor before and probably will again.

Much more dangerous to do so the other way around - non grounding plug on a cord with an equipment grounding conductor. The many cords out there with broken off grounding conductor pin are no different.

I don't see why having an unused EGC terminal on a cord should be a big deal. You kind of have similar thing with a grounding type receptacle when you plug a two wire cord into it - the EGC is there but is not needed, and does not attach to anything in the plugged in equipment.
 
kwired said:
Looks like that is the correct answer.

I have used grounding attachment plugs on cords with no equipment grounding conductor before and probably will again.

Much more dangerous to do so the other way around - non grounding plug on a cord with an equipment grounding conductor. The many cords out there with broken off grounding conductor pin are no different.

I don't see why having an unused EGC terminal on a cord should be a big deal. You kind of have similar thing with a grounding type receptacle when you plug a two wire cord into it - the EGC is there but is not needed, and does not attach to anything in the plugged in equipment.
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Usually if an appliance or tool is two prong it is double insulated. By using a cord with an unused EGC the safety of thinking the cord is grounded could be shocking exsperience.
 
Gregg Harris said:
Usually if an appliance or tool is two prong it is double insulated. By using a cord with an unused EGC the safety of thinking the cord is grounded could be shocking exsperience.
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How many users see three prong cord and think about it being safer?

How many users know the tool still operates with only the two wires but have no idea as to why and will use adapters if necessary or even break off that third prong?

If the tool is double insulated, how is it you are introducing any hazard by putting on a grounding type plug, with or without an equipment grounding conductor installed?
 
K8MHZ said:
I can't remember where, but I saw a two wire cord with a molded three prong plug factory installed on a device. I think it may have been some sort of personal computer peripheral.
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Pretty effective at maintaining a certain polarity isn't it?
 
K8MHZ said:
No more so than a correctly constructed two wire plug. The neutral should be so big there is no way to insert it into the hot slot without nearly destroying the receptacle.
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Correct, I think I did say "pretty effective" and not 'more/less" effective:p
 
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