will 240 volt a/c unit work without grounding wire?
- Thread starter jmmyers
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Re: will 240 volt a/c unit work without grounding wire?
yes. the green wire is not part of the normal circuit. it is only there to provide a fault current path.
not having it is a code violation and a safety hazard, but it would still work.
yes. the green wire is not part of the normal circuit. it is only there to provide a fault current path.
not having it is a code violation and a safety hazard, but it would still work.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Re: will 240 volt a/c unit work without grounding wire?
Ex: hot wire slips off inside the A/C unit and touches the case. fault current flows through the green wire back to the panel and trips the breaker. if the green wire is open, no fault current flows to trip the breaker, and the case of the A/C unit is hot, just waiting for someone to touch it.
The fault current path is there to provide a current path to trip the branch circuit OCPD. if that path is open, and a ground fault occured, the OCPD would not clear the fault.
Ex: hot wire slips off inside the A/C unit and touches the case. fault current flows through the green wire back to the panel and trips the breaker. if the green wire is open, no fault current flows to trip the breaker, and the case of the A/C unit is hot, just waiting for someone to touch it.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: will 240 volt a/c unit work without grounding wire?
Just a thought. The refridgerant line that run back to the "A" coil will try to fault the current via the EGC to the furance which is not sized to carry this fault current. also if the connection between the "A" coil and furnace is not very good (rubber mounting) it could cause an arc flash that could cause a fire.
Just a thought. The refridgerant line that run back to the "A" coil will try to fault the current via the EGC to the furance which is not sized to carry this fault current. also if the connection between the "A" coil and furnace is not very good (rubber mounting) it could cause an arc flash that could cause a fire.
Re: will 240 volt a/c unit work without grounding wire?
Equipment grounding (bonding) is not necessary for equipment to function.
It is necessary for a safe electrical installation & of course to meet NEC.
Think of a car in which the spare tire in the trunk is flat. The spare will not help you when you need it.
If the equipment grounding (bonding) path is not good, it will not help you when you need it.
Equipment grounding (bonding) is not necessary for equipment to function.
It is necessary for a safe electrical installation & of course to meet NEC.
Think of a car in which the spare tire in the trunk is flat. The spare will not help you when you need it.
If the equipment grounding (bonding) path is not good, it will not help you when you need it.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: will 240 volt a/c unit work without grounding wire?
I must ask why your asking this question.If your an inspector should we assume you seen this violation ?
I must ask why your asking this question.If your an inspector should we assume you seen this violation ?
Re: will 240 volt a/c unit work without grounding wire?
Well thanks for all the replies fellows. Yes, I have seen this on several occasions. Yes, I do know what the dangers are.
One of my biggest concerns regarding this issue would of course be if one of those hot wires was to energize the motor, the frame and possibly the ground around it.
While you have said that in different words, I do believe we are all on the same playing field.
One last question to play with. Is FMC (or Greenfield if you are going by the trade name) suitable as the grounding conductor for that connection?
Is it legal, according to the NEC, to have the green grounding wire properly attached and have the connections made between the unit, the disconnect and the panel with FMC (Greenfield if you are going by the trade name)?
One last teaser....if you are making the connection at an equipment panel, does the grounding wire get attached to the floating neutral bar, or the grounding bar?
Thanks again.
Joe Myers
Joe Myers
Well thanks for all the replies fellows. Yes, I have seen this on several occasions. Yes, I do know what the dangers are.
One of my biggest concerns regarding this issue would of course be if one of those hot wires was to energize the motor, the frame and possibly the ground around it.
While you have said that in different words, I do believe we are all on the same playing field.
One last question to play with. Is FMC (or Greenfield if you are going by the trade name) suitable as the grounding conductor for that connection?
Is it legal, according to the NEC, to have the green grounding wire properly attached and have the connections made between the unit, the disconnect and the panel with FMC (Greenfield if you are going by the trade name)?
One last teaser....if you are making the connection at an equipment panel, does the grounding wire get attached to the floating neutral bar, or the grounding bar?
Thanks again.
Joe Myers
Joe Myers
pierre
Senior Member
- Location
- Westchester County, New York
Re: will 240 volt a/c unit work without grounding wire?
Actually if I were to use the car as an analogy, I would say the car can run, but when you go to step on the brakes, they would not stop the car
Joe
I hope you are only teasing us and actually know these answers - especially since your bio says you are an inspector. What kind of inspector?
Actually if I were to use the car as an analogy, I would say the car can run, but when you go to step on the brakes, they would not stop the car
Joe
I hope you are only teasing us and actually know these answers - especially since your bio says you are an inspector. What kind of inspector?
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: will 240 volt a/c unit work without grounding wire?
If you are talking about the main service that has a main breaker installed in it then there should be a main bonding jumper installed in this panel that connect's the grounding to the neutral. This main bonding jumper can be a wire, buss, or a screw that has a green finsh. If this jumper is not there then this is a very big and dangerous installation. This jumper has to be at the first means of disconnect of the service, so it could be at a disconnect by the meter. and yes the grounding and neutral conductors have to be kept seperate after this main bonding jumper.
As far as using the FMC for grounding it is only allowed if the circuit is protected by a 20 amp OCPD or less.
Joe you must be talking about a sub panel. (I hope) Yes if this is a sub panel then the faule current would follow the grounding back to the main service where the grounding conductors and the neutral are bonded together to allow the fault current to return back to it's source (transformer).
If you are talking about the main service that has a main breaker installed in it then there should be a main bonding jumper installed in this panel that connect's the grounding to the neutral. This main bonding jumper can be a wire, buss, or a screw that has a green finsh. If this jumper is not there then this is a very big and dangerous installation. This jumper has to be at the first means of disconnect of the service, so it could be at a disconnect by the meter. and yes the grounding and neutral conductors have to be kept seperate after this main bonding jumper.
As far as using the FMC for grounding it is only allowed if the circuit is protected by a 20 amp OCPD or less.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: will 240 volt a/c unit work without grounding wire?
your starting to scare me.Questions like this might come from a 1 year helper but not from a inspector,even if your a HI you should know the answers.
your starting to scare me.Questions like this might come from a 1 year helper but not from a inspector,even if your a HI you should know the answers.
luke warmwater
Senior Member
Re: will 240 volt a/c unit work without grounding wire?
Joe,
I don't know where you're going with this.
As for the grounding of FMC, start with Article 348.
Also look at 348.60
If it matters, Joe is a Home Inspector.
Are you trying to stir us up?
Joe,
I don't know where you're going with this.
As for the grounding of FMC, start with Article 348.
Also look at 348.60
If it matters, Joe is a Home Inspector.
Are you trying to stir us up?
- Location
- Massachusetts
Re: will 240 volt a/c unit work without grounding wire?
Do you know the answers to the questions asked?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Re: will 240 volt a/c unit work without grounding wire?
If he is a HI I can understand why he does not have such basic electrical understanding and the question makes more sense then if he were a building inspector.
At least he seems to know he does not know and is asking somewhere he is likely to get an accurate answer. Better than trying to bluff his way forward if you ask me.
If he is a HI I can understand why he does not have such basic electrical understanding and the question makes more sense then if he were a building inspector.
At least he seems to know he does not know and is asking somewhere he is likely to get an accurate answer. Better than trying to bluff his way forward if you ask me.
Re: will 240 volt a/c unit work without grounding wire?
Hello Bob,
Without looking them up, I would have to say that yes, I know the answers.
More than that I am interested in learning, if the average sparky knows the answer(s).
In my situation, what I know is some extremely irrelevant so the point that what you know is more important. Whether I like it or not, there is always that chance that you know something I don't, or vice versa.
I have always found that of the many installations that I have found to be incorrect, it was not because someone was ignorant, it was they were given incorrect information, or they were taught that way.
While you are seeing this as basic, everyone knows information, you must be standing alone because I can point out several instances when it was done incorrectly.
Anyway...back to the subject....can you please answer those questions, without looking them up. I am more interested in the manner in which they are installed then whether you are right or wrong.
I can assure you that I will not think less of you and certainly you can reciprocate and in the end we will all learn together.
BTW...I make plenty of my own mistakes and I certainly am man enough to stand up and say that I am wrong when I am. Are you?
Joe Myers, (yes, a home inspector)
A & N Inspections, Inc
Hello Bob,
Without looking them up, I would have to say that yes, I know the answers.
More than that I am interested in learning, if the average sparky knows the answer(s).
In my situation, what I know is some extremely irrelevant so the point that what you know is more important. Whether I like it or not, there is always that chance that you know something I don't, or vice versa.
I have always found that of the many installations that I have found to be incorrect, it was not because someone was ignorant, it was they were given incorrect information, or they were taught that way.
While you are seeing this as basic, everyone knows information, you must be standing alone because I can point out several instances when it was done incorrectly.
Anyway...back to the subject....can you please answer those questions, without looking them up. I am more interested in the manner in which they are installed then whether you are right or wrong.
I can assure you that I will not think less of you and certainly you can reciprocate and in the end we will all learn together.
BTW...I make plenty of my own mistakes and I certainly am man enough to stand up and say that I am wrong when I am. Are you?
Joe Myers, (yes, a home inspector)
A & N Inspections, Inc
Re: will 240 volt a/c unit work without grounding wire?
This quote is the best reason that I come here. Here is something that I did not think of, although it is as true as any of the other dangers that I did.
Joe Myers (yes, a home inspector)
A & N Inspections, Inc.
This quote is the best reason that I come here. Here is something that I did not think of, although it is as true as any of the other dangers that I did.
Did you think of that?
Joe Myers (yes, a home inspector)
A & N Inspections, Inc.
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