I install coffee equipment within hotels and such. The requirement is to have 4 wire connections on all 208/240 power. There is some thought that jumpering between the neutral and ground is the same as having a separate ground run back to the panel. I realize code can vary, but what is the code from a liability stand point?
240 volt 4 wire versus 3 wire connections
- Thread starter powell
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bphgravity
Senior Member
- Location
- Florida
Re: 240 volt 4 wire versus 3 wire connections
In no case should a grounding connection be made to a grounded (neutral) connection outside of only a few situations as specified by the code.
Obviously the person who told you this or wherever this "some thought" originated from doesn't know the difference between a grounded and grounding conductor.
The white conductor is the grounded conductor and is usually refered to as the neutral. This conductor is for normal operating current to flow on.
The green or bare is the grounding conductor and is for the clearing of fault current from line to metal and line to ground faults.
If you jump out the two, normal operating current will then flow on the metal parts and grounded parts of the circuit. This is a real and significant hazard.
Please see 250.24(5) and 250.142 of the 2002 NEC for exact code specifications.
In no case should a grounding connection be made to a grounded (neutral) connection outside of only a few situations as specified by the code.
Obviously the person who told you this or wherever this "some thought" originated from doesn't know the difference between a grounded and grounding conductor.
The white conductor is the grounded conductor and is usually refered to as the neutral. This conductor is for normal operating current to flow on.
The green or bare is the grounding conductor and is for the clearing of fault current from line to metal and line to ground faults.
If you jump out the two, normal operating current will then flow on the metal parts and grounded parts of the circuit. This is a real and significant hazard.
Please see 250.24(5) and 250.142 of the 2002 NEC for exact code specifications.
Re: 240 volt 4 wire versus 3 wire connections
On straight 208 or 240 appliances the neutral will be an equipment ground conductor and will be regrounded at the appliance if it is supplied by metal water tubing.
This is the same as regrounding the neutral, but if the wire is green it won't carry any current according to page 207, of Soares Book on Grounding.
On straight 208 or 240 appliances the neutral will be an equipment ground conductor and will be regrounded at the appliance if it is supplied by metal water tubing.
This is the same as regrounding the neutral, but if the wire is green it won't carry any current according to page 207, of Soares Book on Grounding.
pierre
Senior Member
- Location
- Westchester County, New York
Re: 240 volt 4 wire versus 3 wire connections
This is where the lack of drawings and being able to better communicate I think hinders this forum. I am not laying 'blame' on anybody.
Again I am not sure what Bennie is saying, Am I the only one? I hope not.
Bennie believe me I am not picking on you.
If an appliance is straight 208v or 240v single phase, and a 2 conductor with an EGC is connected to that equipment, are you saying that current will travel on that EGC?
Pierre
This is where the lack of drawings and being able to better communicate I think hinders this forum. I am not laying 'blame' on anybody.
Again I am not sure what Bennie is saying, Am I the only one? I hope not.
Bennie believe me I am not picking on you.
If an appliance is straight 208v or 240v single phase, and a 2 conductor with an EGC is connected to that equipment, are you saying that current will travel on that EGC?
Pierre
bphgravity
Senior Member
- Location
- Florida
Re: 240 volt 4 wire versus 3 wire connections
I think what Bennie is talking about is 208V and 240V equipment like a water heater doesnt require a neutral conductor for proper operation and that the EGC will have zero current and only act as an effective fault path.
However, this is not the case for 208V and 240V equipment that has line to neutral loads like dryers and ranges.
The topis starter made it clear that the equipment requires 4 wires. Two ungrounded, a neutral, and a grounding conductor. The unit must have line to neutral loads along with a line to line load, and therefor requires a return conductor that is not connected to the metallic parts of the circuit and equipment.
If the installer bonds the white and green together as suggested in the post, the line-toline loads will not be the problem, but the line-to-neutral loads will be. This current will be present on the metallic case of the equipment, and any other metallic parts of the system. This is a clear hazrd and code violation.
[ July 03, 2003, 07:22 PM: Message edited by: bphgravity ]
I think what Bennie is talking about is 208V and 240V equipment like a water heater doesnt require a neutral conductor for proper operation and that the EGC will have zero current and only act as an effective fault path.
However, this is not the case for 208V and 240V equipment that has line to neutral loads like dryers and ranges.
The topis starter made it clear that the equipment requires 4 wires. Two ungrounded, a neutral, and a grounding conductor. The unit must have line to neutral loads along with a line to line load, and therefor requires a return conductor that is not connected to the metallic parts of the circuit and equipment.
If the installer bonds the white and green together as suggested in the post, the line-toline loads will not be the problem, but the line-to-neutral loads will be. This current will be present on the metallic case of the equipment, and any other metallic parts of the system. This is a clear hazrd and code violation.
[ July 03, 2003, 07:22 PM: Message edited by: bphgravity ]
pierre
Senior Member
- Location
- Westchester County, New York
Re: 240 volt 4 wire versus 3 wire connections
Thanks Bryan, you explained that very well!
Pierre
Thanks Bryan, you explained that very well!
Pierre
Re: 240 volt 4 wire versus 3 wire connections
Good Morning Pierre,
Maybe one or both will become more active again.
Roger
Good Morning Pierre,
There are a couple of members (and friends to the forum) that excell at creating graphics here, Ed MacLaren & ronaldrc.
Maybe one or both will become more active again.
Roger
pierre
Senior Member
- Location
- Westchester County, New York
Re: 240 volt 4 wire versus 3 wire connections
Thanks Roger, I wonder if Ed uses the drawing program that Bill posted in another thread? Hope you had a great 4th!!!
The location along the Hudson River, where I viewed fireworks from I could watch 8 towns' fireworks!!! Including NYC - very awesome!! I was also able to get a couple of BEAUTIFUL sunset pics.
Pierre
Thanks Roger, I wonder if Ed uses the drawing program that Bill posted in another thread? Hope you had a great 4th!!!
The location along the Hudson River, where I viewed fireworks from I could watch 8 towns' fireworks!!! Including NYC - very awesome!! I was also able to get a couple of BEAUTIFUL sunset pics.
Pierre
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