Originally Posted By: bsmith
This post was automatically imported from our archived forum.
http://www.nachi.org/bbsystem/usrimages/D/DSCF0006.JPG ]
Any input will be appreciated. Thanks in advance.
http://www.nachi.org/bbsystem/usrimages/D/DSCF0006.JPG ]
Any input will be appreciated. Thanks in advance.
Originally Posted By: jpope
This post was automatically imported from our archived forum.
You are correct Bill - grounds and neutrals need to be seperate at load side equipment. It doesn’t really matter what you are calling it.
The EGC's should be bonded to the box and the neutrals should be isolated or removed.
Originally Posted By: bsmith
This post was automatically imported from our archived forum.
Thanks Jeff - I love it when I’m right! (It doesn’t happen that often)
Originally Posted By: jpope
This post was automatically imported from our archived forum.
| Quote: |
|
NEC 408.20 Grounding of Panelboards
Grounding conductors shall not be connected to a terminal bar provided for grounded conductors (may be a neutral) unless the bar is identified for the purpose and is located where interconnection between equipment grounding conductors and grounded circuit conductors is permitted or required by Article 250. |
Originally Posted By: rbennett
This post was automatically imported from our archived forum.
Jeff
Not a trick question but how are the contractors getting around this with the "fused disconnect" for AC compressors that are 240 volt and they are feeding them with just three wires -- one black - one white and a ground --no external ground is supplied to the ac unit.
I would think that a 4 wire feed would be required -- neutral and ground would be separated. One does not know how the HVAC company that was the Mfg of the unit built it -- is it all 240 volt and the ground is just for the case or is it a mixture of 120 on one side for the fan and 120 on the other side for the compressor?? Same for a 240 volt large window unit.
BTW this is the norm in this area so it must be correct (three wire)
Your thoughts please sir
rlb
Originally Posted By: jpope
This post was automatically imported from our archived forum.
A single 240 volt, single phase circuit (typical condenser circuit) can be run with three conductors with one being the equipment grounding conductor (EGC). With the alternating current, one conductor will act as the neutral while the other is hot.
Originally Posted By: rbennett
This post was automatically imported from our archived forum.
Thank you for the reply
I agree but about the question above about the dryer?? Is this not the same wiring?
If we took the pig tail off and hard wired it in would this change the wiring??
I have a similar question about garbage disposals --- in our area the are being wired with a plug. Thus wire does not have to be protected.
Waiting
rlb
Originally Posted By: jpope
This post was automatically imported from our archived forum.
Clothes dryers are specifically addressed by the NEC.
The grounded conductor (neutral) can be grounded to the grounding conductor (ground) if certain requirements are met which would allow for a three wire, 240 volt circuit. (NEC 250.140)
Otherwise a separate grounding conductor is required as per 250.134
As for the disposal, that is a 120 volt appliance. What's the question?
Originally Posted By: rbennett
This post was automatically imported from our archived forum.
I looked back at my post and I can see the question
1. About the garbage D -- If hard wired "protected wiring" is required -- If on a plug wire it can be "plug in grade wire" -- Also I would think that it would not be required to be on a dedicated ckt and it should be GFI protected. Remember that the SS sink is floating electrically on plastic pipes in most new homes and a real electrical ground is probably with in feet ie stove, toaster etc. I know that this is a little off the thread but sure would like your thoughts
2. The real question is the difference between a drier and an AC unit one is 4 wire and the other is 3 wire with the disconnect called a sub panel and the other called a disconnect.
3. I realize that the above is more for knowledge than anything that we can do at a site to challenge the "experts" but it is good to know
thanks again
rlb
Originally Posted By: Greg Fretwell
This post was automatically imported from our archived forum.
If this was wired pre 96 code you will be able to use the dryer/range exception for using the grounded conductor as the equipment ground.
Originally Posted By: Greg Fretwell
This post was automatically imported from our archived forum.
Virtually all AC condensers will not require a grounded conductor be brought to the equipment, only the equipment grounding conductor since there is no line to neutral load.
That is the same as the NEMA 6-15 and 6-20 receptacles that only take 3 prong plugs
Originally Posted By: rbennett
This post was automatically imported from our archived forum.
What about today??
Originally Posted By: rbennett
This post was automatically imported from our archived forum.
Greg
So if we know that the device is 240 volt we only have to run a ground
If it uses some 120 Volts on one side of the line and 120 loads on the other side of the line then it should be a 4 wire ckt
And how do we know because the device will work no matter how it is wired?
Major concern is the AC unit wired with three wires and stove plugs with 4 wires
Is it a subpanel or a disconnect point (ground and neutral commoned)
Maybe this is a local issue and there is a basic misunderstanding of ohm's law
rlb