We are on a project that consist of 30 apartments on 5-floors,the apartments have individual 125amp single phase panels for each tenant.These panels are fed from the main electric room in the basement-it was called out on the plans to feed the panels with 2/0 MC cable-which we have completed.Heres the issue:Each apartment has a heat pump-unfortunatly they were installed ,before we realized they were 3ph.The mech.contractors have already priced replacing the units or components to go to single phase-however it is not only very costly but due to the units already being plummed -it would void the UL listings.We also priced phase converters-but the owner does not want to deal with the maintenance of the converters.The engineer has asked us to look into the possibility of using the un-insulated condutor in the MC cable as the grounded conductor,and using the MC jacket as the EG.We are trying to work with the engineer(he is bearing the cost of the rework),but I cant find where this type of design would be code compliant.Any thoughts?thanks for the help...
un-insulated grounded conductor
- Thread starter jflynn
- Start date
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Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
- Occupation
- Facility Senior Electrician
un-insulated conductor in MC????
I'm not familiar. How would the un-insulated conductor not be bonded to the jacket?
I'm not familiar. How would the un-insulated conductor not be bonded to the jacket?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Someone is concerned about the voiding a listing on the on the heat pump but not worried about a big NEC violation not to mention likely violating the listing on the cable?
Mvillines
Senior Member
- Location
- Western KY on the Ohio River
As previously said, Don?t do it! Check out sections 250.24 (A)(5) and 215.12(A), that refers to 200.6. These are the sections I can think to prohibit this use. The only exception that I know that permits the grounded conductor to be uninsulated is 230.41 exception.
paul
Senior Member
- Location
- Snohomish, WA
They screwed up! Plain and simple. There is no short-cut fix on it. Replace the wire or the units.
As twoskinoneman asks, What is the "uninsulated conductor" in MC ?
If it has an uninsulated conductor I believe it's either the newer style MC
where the sheath is a equipment ground or AC where the sheath also is an equipment ground.
Don't take it ti the bank, but if you have an uninsulated conductor, I think your "cable" is an approved equipment ground
If it has an uninsulated conductor I believe it's either the newer style MC
where the sheath is a equipment ground or AC where the sheath also is an equipment ground.
Don't take it ti the bank, but if you have an uninsulated conductor, I think your "cable" is an approved equipment ground
jeremysterling
Senior Member
- Location
- Austin, TX
Agreed. Sounds like MCAP that has the bare AL bonding jumper. Please do not even think about putting a load on this joke of a conductor.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
If this is in fact MCap, then the bare conductor is part of the sheath listing, providing it to have the sheath as an equipment ground path.
It cannot be used for a circuit conductor (grounded or ungrounded conductor).
As has been mentioned, there is no short cut here. I rework of the installation will have to occur, whether it is the cables or the service or the equipment.
It cannot be used for a circuit conductor (grounded or ungrounded conductor).
As has been mentioned, there is no short cut here. I rework of the installation will have to occur, whether it is the cables or the service or the equipment.
Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
- Occupation
- Facility Senior Electrician
Joke of a conductor? The MCAP has a 10awg al bonding wire.
But I absolutely agree with jeremysterling and the others... don't try to load it. Besides it will just short out since it is bonded to the metallic sheath.
Really you deserve forthy lashes for even considering it
If the MC cable in question is in fact Southwire's MCAP then (as I understand it) the bonding wire alone is NOT the grounding path. According to Southwire, it is a combination of:
"A full-sized bare aluminum grounding conductor, located outside the Mylar tape covering, which is in direct contact with the interlocked armor throughout the entire cable length."
"This allows the armor of MCAP cable to serve as an equipment grounding conductor with full UL and NEC compliance. The MCAP cable armor ground path is equivalent to the green copper ground in conventional MC cable."
...This may account for why said internal bonding wire does not require termiantion...
Great info explaining Southwire's MCAP cable can be found here:
http://www.southwire.com/Southwire/StaticFiles/Text/MCCableCrosses.pdf
I do hope this is helpful,
Mweaver
"A full-sized bare aluminum grounding conductor, located outside the Mylar tape covering, which is in direct contact with the interlocked armor throughout the entire cable length."
"This allows the armor of MCAP cable to serve as an equipment grounding conductor with full UL and NEC compliance. The MCAP cable armor ground path is equivalent to the green copper ground in conventional MC cable."
...This may account for why said internal bonding wire does not require termiantion...
Great info explaining Southwire's MCAP cable can be found here:
http://www.southwire.com/Southwire/StaticFiles/Text/MCCableCrosses.pdf
I do hope this is helpful,
Mweaver
Last edited:
electricalperson
Senior Member
- Location
- massachusetts
lets see pics of the wire
As has been mentioned, there is no short cut here. I rework of the installation will have to occur, whether it is the cables or the service or the equipment.[/QUOTE]
I agree with you-
As I mentioned in my OP -I could not find where it would be code compliant.I told the engineer that I would do some research-as always this forum is a great place for research/answers-thanks to all...
I agree with you-
As I mentioned in my OP -I could not find where it would be code compliant.I told the engineer that I would do some research-as always this forum is a great place for research/answers-thanks to all...
[
"A full-sized bare aluminum grounding conductor, located outside the Mylar tape covering, which is in direct contact with the interlocked armor throughout the entire cable length."
THE CABLE WE HAVE DOES HAVE A FULL SIZE EG-AND IT IS WITH ALL THE OTHER CONDUCTORS COVERED WITH THE MYLAR COVERING-THE BARE CONDUCTOR IS NOT IN CONTACT WITH THE JACKET.
...This may account for why said internal bonding wire does not require termiantion...
Great info explaining Southwire's MCAP cable can be found here:
http://www.southwire.com/Southwire/StaticFiles/Text/MCCableCrosses.pdf
I do hope this is helpful,-:grin:
Mweaver[/QUOTE]
"A full-sized bare aluminum grounding conductor, located outside the Mylar tape covering, which is in direct contact with the interlocked armor throughout the entire cable length."
THE CABLE WE HAVE DOES HAVE A FULL SIZE EG-AND IT IS WITH ALL THE OTHER CONDUCTORS COVERED WITH THE MYLAR COVERING-THE BARE CONDUCTOR IS NOT IN CONTACT WITH THE JACKET.
...This may account for why said internal bonding wire does not require termiantion...
Great info explaining Southwire's MCAP cable can be found here:
http://www.southwire.com/Southwire/StaticFiles/Text/MCCableCrosses.pdf
I do hope this is helpful,-:grin:
Mweaver[/QUOTE]
Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
- Occupation
- Facility Senior Electrician
The bare conductor is not in contact with the jacket????
I also would love to see a pic if you can provide one.
JohnJ0906
Senior Member
- Location
- Baltimore, MD
I've seen (used) MC cable with an uninsulated EGC, 1/0 AL, EGC was #2 as I recall. The bare was contained inside the Mylar. It definitely wasn't MC-AP (before that was developed)
No pics, sorry.
ArcNSpark
Member
- Location
- Coventry, RI
Call me petty if you want, but there will be a snowy day in hell before I go even one inch out of my way to make life easier for an engineer or architect.
I know it's a good business practice, but I don't own the company. Therefore my experience with suit-wearing guys on a worksite consists of them making countless changes and blaming the working guys for not guessing how to do it right the first time.
Ok...now that's off my chest. Please continue.
I know it's a good business practice, but I don't own the company. Therefore my experience with suit-wearing guys on a worksite consists of them making countless changes and blaming the working guys for not guessing how to do it right the first time.
Ok...now that's off my chest. Please continue.
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