Sub-Panel?
- Thread starter bennie
- Start date
- Status
- Location
- Massachusetts
Re: Sub-Panel?
It is "load side equipment" 250.142(B) and a feeder to this panel is treated the same way a feeder to any other piece of load side equipment.
What is the need to describe it?
It is not the panel with the service disconnect, once that is established what more do we need to know?
Just my opinion here, but I do not see why it would have to.
It is "load side equipment" 250.142(B) and a feeder to this panel is treated the same way a feeder to any other piece of load side equipment.
What is the need to describe it?
It is not the panel with the service disconnect, once that is established what more do we need to know?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Sub-Panel?
SWAG - it doesn't care.
It appears the NEC is only interested in specifics, if the panel is part of the service entrance equipment. All non-service entrance panels are treated equally regardless of there physical or electrical location.
SWAG - it doesn't care.
It appears the NEC is only interested in specifics, if the panel is part of the service entrance equipment. All non-service entrance panels are treated equally regardless of there physical or electrical location.
Re: Sub-Panel?
In the old days
We called a panel that had to be added to the existing lighting panel, an outboard panel. An outboard panel was added, and connected, as a service panel.
Some of the times the panel would be near the new load, a switch would be at the service entrance panel location.
We could install up to six outboard panels on one dwelling. This was like adding a new service when new appliances were installed. This method was cost effective, when you factor in this increase in load happened during the great depression.
This is the reason I maintain all panels are service panels, regardless of location.
As I have stated before; The reason the NEC does not mention Sub-Panel is because they do not exist.
In the old days
We called a panel that had to be added to the existing lighting panel, an outboard panel. An outboard panel was added, and connected, as a service panel.Some of the times the panel would be near the new load, a switch would be at the service entrance panel location.
We could install up to six outboard panels on one dwelling. This was like adding a new service when new appliances were installed. This method was cost effective, when you factor in this increase in load happened during the great depression.
This is the reason I maintain all panels are service panels, regardless of location.
As I have stated before; The reason the NEC does not mention Sub-Panel is because they do not exist.
charlie
Senior Member
- Location
- Indianapolis
Re: Sub-Panel?
You are right Bennie, sub-panels do not exist. If you look at my posts, I normally use the term distribution panelboard or downstream panelboard.
Now to address your comment, in the old days, we didn't run a separate grounding conductor. The "tail panels" were connected directly to the main bus and the tap was run to it without anything to ground it but the neutral. Essentially, it was part of the main service equipment.
That was then, this is now. You are now required to keep the grounding conductors separate from the grounded conductors. You can't reground the neutral after you leave the service equipment. Therefore, the downstream panelboarrds are just another piece of equipment that must be grounded like any other piece of equipment.
Now a question for you. Why does the Code need to define a downstream panelboard?
You are right Bennie, sub-panels do not exist. If you look at my posts, I normally use the term distribution panelboard or downstream panelboard.
Now to address your comment, in the old days, we didn't run a separate grounding conductor. The "tail panels" were connected directly to the main bus and the tap was run to it without anything to ground it but the neutral. Essentially, it was part of the main service equipment.
That was then, this is now. You are now required to keep the grounding conductors separate from the grounded conductors. You can't reground the neutral after you leave the service equipment. Therefore, the downstream panelboarrds are just another piece of equipment that must be grounded like any other piece of equipment.
Now a question for you. Why does the Code need to define a downstream panelboard?
Re: Sub-Panel?
Charlie: The rest of my story is; The code is not any different today as it was in the old days.
Only the persons reading the code and fabricating an explanation of the intent has changed.
I believe I have shown how a water heater will re ground the neutral, if there is metal water pipe.
I forgot that some people think that only fault current will flow in a bare or green wire.
Charlie: The rest of my story is; The code is not any different today as it was in the old days.
Only the persons reading the code and fabricating an explanation of the intent has changed.
I believe I have shown how a water heater will re ground the neutral, if there is metal water pipe.
I forgot that some people think that only fault current will flow in a bare or green wire.
Re: Sub-Panel?
Sorry Charlie: I didn't answer your question.
In my opinion and my interpretation of the NEC and the evolution of new methods, I feel the absence of a definition of a sub panel is due to the definition being the panels are all service panels, and can be connected accordingly.
The only requirement is to prevent objectionable current flow by observing 250.6 in its entirety.
3 wire cable does not present multiple ground points, so separation of ground and neutral conductors are not necessary.
When 4 wires are used the ground/neutral separation must be made to eliminate one of the ground paths.
[ March 04, 2004, 05:47 PM: Message edited by: bennie ]
Sorry Charlie: I didn't answer your question.
In my opinion and my interpretation of the NEC and the evolution of new methods, I feel the absence of a definition of a sub panel is due to the definition being the panels are all service panels, and can be connected accordingly.
The only requirement is to prevent objectionable current flow by observing 250.6 in its entirety.
3 wire cable does not present multiple ground points, so separation of ground and neutral conductors are not necessary.
When 4 wires are used the ground/neutral separation must be made to eliminate one of the ground paths.
[ March 04, 2004, 05:47 PM: Message edited by: bennie ]
- Location
- Massachusetts
Re: Sub-Panel?
Why does the NEC not address or define a service panel?
Why does the NEC not address or define a service panel?
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: Sub-Panel?
Because there is no need to. "Service equipment" and "other than service equipment" are perfectly adequate.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Sub-Panel?
At the Bangor Submarine Base near here, there are 8 or so Trident nuclear subs. They have sub panels.
At the Bangor Submarine Base near here, there are 8 or so Trident nuclear subs. They have sub panels.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Sub-Panel?
Good one Tom. LOL
[ March 04, 2004, 11:39 PM: Message edited by: hurk27 ]
Good one Tom.
LOL [ March 04, 2004, 11:39 PM: Message edited by: hurk27 ]
bill addiss
Senior Member
Re: Sub-Panel?
Tom,
.... I just got it!
Bill
Tom,
.... I just got it!
Bill
caosesvida
Senior Member
Re: Sub-Panel?
Maybe "sub panel" is just the common name for it. Its kind of long to state "not the service disconnect" panel. The code makes changes because of changes, at some point it must have become an issue that "sub panels" should have 4 wires, as did mobile homes. Perhaps there was some problem that came up with the 3 wire system. Why have we gone to 4 wire to dryers from the service disconnect?
Maybe "sub panel" is just the common name for it. Its kind of long to state "not the service disconnect" panel. The code makes changes because of changes, at some point it must have become an issue that "sub panels" should have 4 wires, as did mobile homes. Perhaps there was some problem that came up with the 3 wire system. Why have we gone to 4 wire to dryers from the service disconnect?
charlie
Senior Member
- Location
- Indianapolis
Re: Sub-Panel?
I don't know where this is all coming from but, Bennie, do you have any concept how much noise will be put onto the "grounding system" if the neutral were used for the current return and the grounding? Most of the current will naturally follow the circuit but a good portion will be on the steel. I can also see the conduit getting hot where the joints were not made up tight enough (the conduit will become the major current return).
As far as requiring four wire circuits for an electric dryer, several people have gotten shocked and one electrocuted while working or leaning on the washer (grounded to a non-current carrying grounding conductor) and the dryer (grounded to the neutral). It is time to ground everything to the grounding system and forget about trying to ground to the neutral.
I don't know where this is all coming from but, Bennie, do you have any concept how much noise will be put onto the "grounding system" if the neutral were used for the current return and the grounding? Most of the current will naturally follow the circuit but a good portion will be on the steel. I can also see the conduit getting hot where the joints were not made up tight enough (the conduit will become the major current return).
As far as requiring four wire circuits for an electric dryer, several people have gotten shocked and one electrocuted while working or leaning on the washer (grounded to a non-current carrying grounding conductor) and the dryer (grounded to the neutral). It is time to ground everything to the grounding system and forget about trying to ground to the neutral.
charlie
Senior Member
- Location
- Indianapolis
Re: Sub-Panel?
Bennie, it is grounded at the service, not downstream. You can't have current flow without having a circuit. The only time the building steel, water, etc. with have any current flowing on it is under ground fault conditions.
What you are saying is that you can get electrocuted if you touch a phase wire. Not unless you have a complete circuit. That is why we get good enough to think we can work hot. It is amazing I am still alive.
Bennie, it is grounded at the service, not downstream. You can't have current flow without having a circuit. The only time the building steel, water, etc. with have any current flowing on it is under ground fault conditions.
What you are saying is that you can get electrocuted if you touch a phase wire. Not unless you have a complete circuit. That is why we get good enough to think we can work hot. It is amazing I am still alive.
- Location
- Illinois
- Occupation
- retired electrician
Re: Sub-Panel?
Bennie,
How is the grounded conductor bonded downstream of the service disconnect in an installation that is in compliance with the NEC? (assuming a single building istallation)
Don
Bennie,
How is the grounded conductor bonded downstream of the service disconnect in an installation that is in compliance with the NEC? (assuming a single building istallation)
Don
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Sub-Panel?
If the neutral is grounded in other places down stream of the main service disconnect we would not be allowed to not count the EGC's as a non-current carrying conductor when doing fill calculations. The EGC's should not be carrying current in a NEC compliant installation. This is the intent of the NEC to stop current from flowing on the EGC's as it can be a shock and a fire hazard. This is spelled out by the requirment of not allowing 3 wire feeders to an out building with other common metal paths between the two buildings. this is because other paths would be at one potential and the neutral could be at another. then any contact between the two could result in a shock. I have seen where a cable coax caught on fire from current flowing through it from a bond at a remote building. the remote building was fed with only three conductors from the main building the cable was bonded at both locations. the voltage drop in the neutral caused a high current on the cable coax that it was not designed to carry. This is just one example. other paths when a remote panel is in the same building like A/C duct's, water pipes, low-voltage cables. This has been a problem over the years with sound systems in clubs as any current over the grounding systems will cause problems with the cables between parts of the system when one is on a circuit from one panel and the other is on a circuit from the remote panel, If there is a common bond on each ened of this cable the voltage drop of the remote panels neutral will be placed on this very small wire. Not a good idea is it.
If the neutral is grounded in other places down stream of the main service disconnect we would not be allowed to not count the EGC's as a non-current carrying conductor when doing fill calculations. The EGC's should not be carrying current in a NEC compliant installation. This is the intent of the NEC to stop current from flowing on the EGC's as it can be a shock and a fire hazard. This is spelled out by the requirment of not allowing 3 wire feeders to an out building with other common metal paths between the two buildings. this is because other paths would be at one potential and the neutral could be at another. then any contact between the two could result in a shock. I have seen where a cable coax caught on fire from current flowing through it from a bond at a remote building. the remote building was fed with only three conductors from the main building the cable was bonded at both locations. the voltage drop in the neutral caused a high current on the cable coax that it was not designed to carry. This is just one example. other paths when a remote panel is in the same building like A/C duct's, water pipes, low-voltage cables. This has been a problem over the years with sound systems in clubs as any current over the grounding systems will cause problems with the cables between parts of the system when one is on a circuit from one panel and the other is on a circuit from the remote panel, If there is a common bond on each ened of this cable the voltage drop of the remote panels neutral will be placed on this very small wire. Not a good idea is it.
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