Service Neutral
- Thread starter kiss
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Re: Service Neutral
My complaint is; Insinuating a transfer switch that switches the neutral, when there is a solid connection to the other supply, is a separately derived system.
The thread about a winding to winding fault is a good example of my concern. The fault would take out the emergency along with the service system.
A separate switch to lift the equipment ground from the service system,would make the emergency system separately derived.
My complaint is; Insinuating a transfer switch that switches the neutral, when there is a solid connection to the other supply, is a separately derived system.
The thread about a winding to winding fault is a good example of my concern. The fault would take out the emergency along with the service system.
A separate switch to lift the equipment ground from the service system,would make the emergency system separately derived.
Ed MacLaren
Senior Member
Re: Service Neutral
Whether the neutral is switched or solidly connected in each transfer switch depends on whether that particular system is configured as an SDS or not. Each one should be evaluated separately.
When a generator's winding neutral is bonded to the frame, it's transfer switch must open the neutral conductor. This will require the generator system neutral to be connected to an acceptable grounding electrode.
When a generator's winding neutral is isolated from the frame (not bonded), the neutral conductor may be unswitched, if ground fault protection (GFP) is not installed.
Ed
[ March 12, 2004, 09:28 AM: Message edited by: Ed MacLaren ]
kiss, there may not be any cause for concern. Each of these transfer switches may be correct for it's application.
Whether the neutral is switched or solidly connected in each transfer switch depends on whether that particular system is configured as an SDS or not. Each one should be evaluated separately.
When a generator's winding neutral is bonded to the frame, it's transfer switch must open the neutral conductor. This will require the generator system neutral to be connected to an acceptable grounding electrode.
When a generator's winding neutral is isolated from the frame (not bonded), the neutral conductor may be unswitched, if ground fault protection (GFP) is not installed.
Ed
[ March 12, 2004, 09:28 AM: Message edited by: Ed MacLaren ]
Re: Service Neutral
Ed: I agree with you, but all my automatic transfer switches 2pole, 3pole and 4pole are all connected to 1 generator. I understand you
correctly about the bonding and grounding of the neutral. But I believe you CAN'T have it both ways and not be concerned about back feed.
Ed: I agree with you, but all my automatic transfer switches 2pole, 3pole and 4pole are all connected to 1 generator. I understand you
correctly about the bonding and grounding of the neutral. But I believe you CAN'T have it both ways and not be concerned about back feed.
Re: Service Neutral
kiss, you are correct to be concerned. A generator may not have enough available fault current to trip an internal logic circuit breaker. This is why many generators have external logic for assistance (GFP).
A fault from an active line conductor, to the neutral, can and will energize the service and generator neutral, until an overcurrent device activates.
kiss, you are correct to be concerned. A generator may not have enough available fault current to trip an internal logic circuit breaker. This is why many generators have external logic for assistance (GFP).
A fault from an active line conductor, to the neutral, can and will energize the service and generator neutral, until an overcurrent device activates.
Ed MacLaren
Senior Member
Re: Service Neutral
In a forum like this, it is difficult to get beyond the basic principles, and do justice to the specifics of a complex system.
Ed
Sorry kiss, I didn't read your first post carefully enough. You probably do have cause for concern.
In a forum like this, it is difficult to get beyond the basic principles, and do justice to the specifics of a complex system.
Ed
Re: Service Neutral
kiss if you have several transfer switches connected to a single generator, with some switching the neutral and some do not, you have a problem...I think you have heard enough to know you cannot mix them. There is only one way to fix it.
kiss if you have several transfer switches connected to a single generator, with some switching the neutral and some do not, you have a problem...I think you have heard enough to know you cannot mix them. There is only one way to fix it.
pierre
Senior Member
- Location
- Westchester County, New York
Re: Service Neutral
Kiss
IF all of your transfer switches are connected to the same generator, you have two choices.
1. All the transfer switches will be required to be switching the grounded conductor (neutral).
or
2. All the transfer switches will be required to not switch the grounded conductor (neutral).
You cannot as has been said mix the two types of transfer switches with one generator.
The rest of this thread is very interesting in the fact that it is sometimes hard to show on a thread like this exactly what happens to current flow. If one tries to treat each source separately, then it is easier to follow the current flow. Remember that all of the electrons that leave the source ultimately want to get back to that same source. Therefore you will not see current trying to travel from one source to the other source.
Pierre
Kiss
IF all of your transfer switches are connected to the same generator, you have two choices.
1. All the transfer switches will be required to be switching the grounded conductor (neutral).
or
2. All the transfer switches will be required to not switch the grounded conductor (neutral).
You cannot as has been said mix the two types of transfer switches with one generator.
The rest of this thread is very interesting in the fact that it is sometimes hard to show on a thread like this exactly what happens to current flow. If one tries to treat each source separately, then it is easier to follow the current flow. Remember that all of the electrons that leave the source ultimately want to get back to that same source. Therefore you will not see current trying to travel from one source to the other source.
Pierre
- Location
- Massachusetts
Re: Service Neutral
And as long as you do not mind using the equipment grounding conductor, which may be EMT and boxes for a neutral conductor.
Re: Service Neutral
Bob: I think we are on different topics. There will be no difference if the neutrals are solid feed through or switched.
Forget the GFP desensitizing theory, there is likely no GFP's in this system.
The only way to disconnect the service neutral from ths premises wiring system, is to disconnect the service neutral from the premises wiring system.
Then the premises wiring system is a separately derived system.
[ March 12, 2004, 05:24 PM: Message edited by: bennie ]
Bob: I think we are on different topics. There will be no difference if the neutrals are solid feed through or switched.
Forget the GFP desensitizing theory, there is likely no GFP's in this system.
The only way to disconnect the service neutral from ths premises wiring system, is to disconnect the service neutral from the premises wiring system.
Then the premises wiring system is a separately derived system.
[ March 12, 2004, 05:24 PM: Message edited by: bennie ]
Re: Service Neutral
There apparently is a lot of dogs being electrocuted in New York, due to excavation crews cutting the lines. The utility crews are reversing the line and ground, energizing the metal covers on man holes.
A transfer switch, properly connected, would not transfer back to normal power when there is a reversal of polarity.
A transfer switch connected according to these diagrams will kill all the dogs in the area.
There apparently is a lot of dogs being electrocuted in New York, due to excavation crews cutting the lines. The utility crews are reversing the line and ground, energizing the metal covers on man holes.
A transfer switch, properly connected, would not transfer back to normal power when there is a reversal of polarity.
A transfer switch connected according to these diagrams will kill all the dogs in the area.
- Location
- Massachusetts
Re: Service Neutral
Bennie forgetting about the GFP breakers which where I work are everywhere, and forgetting the SDS debate.
This mix of solid and switched neutrals that Kiss has will cause current (the unbalanced neutral current) flow on some of the equipment grounding conductors.
Bob
Bennie forgetting about the GFP breakers which where I work are everywhere, and forgetting the SDS debate.
This mix of solid and switched neutrals that Kiss has will cause current (the unbalanced neutral current) flow on some of the equipment grounding conductors.
Bob
- Location
- Massachusetts
Re: Service Neutral
Bennie we have been losing dogs in Boston too, and it is result of no grounding of manhole covers not any reversing of connections
Bennie we have been losing dogs in Boston too, and it is result of no grounding of manhole covers not any reversing of connections
Re: Service Neutral
I have worked a few man holes. The covers are rarely grounded.
They have to be isolated from the active line wires.
How are the line conductors making contact with the cover? It is difficult to have a situation where the line cables can reach the cover.
The grounded covers are the ones killing the dogs when the polarity is reversed.
I have worked a few man holes. The covers are rarely grounded.
They have to be isolated from the active line wires.
How are the line conductors making contact with the cover? It is difficult to have a situation where the line cables can reach the cover.
The grounded covers are the ones killing the dogs when the polarity is reversed.
websparky
Senior Member
- Location
- Cleveland, Ohio
Re: Service Neutral
Bennie,
You said..
Can you come up with any supporting data for your theory?
[ March 12, 2004, 06:37 PM: Message edited by: websparky ]
Bennie,
You said..
The last statement is your opinion. If we agreed with your opinion and you were in fact able to back it up with some hard evedence, then the rest of your theory through out this thread would be believable. The trouble is, when scientist and researchers make an error in judgement early in their calculations, the rest of their calculations are flawed based on the original error and the results are equally skewed.
Can you come up with any supporting data for your theory?
[ March 12, 2004, 06:37 PM: Message edited by: websparky ]
- Location
- Illinois
- Occupation
- retired electrician
Re: Service Neutral
Bennie,
Don
Bennie,
In all of these cases where I have been able to find any real information, they involved hadholes and not manholes. It is not uncommon to have the conductors touching the ungrounded metal handhole cover and over time the traffic vibration can cause the insulation to be worn through. Some of the other cases have involved energized poles due to the lack of an EGC. I've never seen any report that said they were caused by reverse polarity.
Don
Re: Service Neutral
Don: You are correct for most of the cases. Locally we had an incident where a sprinkler crew cut a buried cable and reversed the equipment ground conductor with an active line.
When the photo cell kicked on, all the light poles were energized.
There is a story about an excavation crew using yellow warning tape to insulate a splice.
There is some cases of LG reversal.
Don: You are correct for most of the cases. Locally we had an incident where a sprinkler crew cut a buried cable and reversed the equipment ground conductor with an active line.
When the photo cell kicked on, all the light poles were energized.
There is a story about an excavation crew using yellow warning tape to insulate a splice.
There is some cases of LG reversal.
Re: Service Neutral
A generator winding is the same as a transformer secondary. The transformer primary is equal to an exciter in a generator. Both provide a magnetic field and relative motion.
When a premises wiring system is supplied by a transformer, and only connected by magnetic coupling, no direct electrical connection, the premises wiring system is an AC system without external connections.
When a premises wiring system is supplied by a generator, and not electrically connected to another source, it is an AC system without external connections.
The main concern when AC was adopted for domestic power, was the fear of a winding to winding fault.
All transformers will fail, the first failure is usually a high to low fault, that eventually develops into a ground fault.
When the premises wiring system sees this fault, the first thing is the, on line, appliances get fried, lamps blow out and clear the circuit. When the active side clears, the neutral side is still a complete circuit to earth. There is nothing to clear this fault except the primary fusing.
A transfer switch must electrically isolate the premises system to be considered a separate system.
The load current on the equipment ground theory is a fabricated hypothesis to explain why the neutral should be switched.
Routing equipment ground conductors to make all connections dead ended will correct any objectionable current flow.
I am challenged to prove my statements, I will return the same request. Prove my statements are untrue and I will post a retraction.
A generator winding is the same as a transformer secondary. The transformer primary is equal to an exciter in a generator. Both provide a magnetic field and relative motion.
When a premises wiring system is supplied by a transformer, and only connected by magnetic coupling, no direct electrical connection, the premises wiring system is an AC system without external connections.
When a premises wiring system is supplied by a generator, and not electrically connected to another source, it is an AC system without external connections.
The main concern when AC was adopted for domestic power, was the fear of a winding to winding fault.
All transformers will fail, the first failure is usually a high to low fault, that eventually develops into a ground fault.
When the premises wiring system sees this fault, the first thing is the, on line, appliances get fried, lamps blow out and clear the circuit. When the active side clears, the neutral side is still a complete circuit to earth. There is nothing to clear this fault except the primary fusing.
A transfer switch must electrically isolate the premises system to be considered a separate system.
The load current on the equipment ground theory is a fabricated hypothesis to explain why the neutral should be switched.
Routing equipment ground conductors to make all connections dead ended will correct any objectionable current flow.
I am challenged to prove my statements, I will return the same request. Prove my statements are untrue and I will post a retraction.
Ed MacLaren
Senior Member
Re: Service Neutral
Ed
My understanding of the term "dead ended", as applied to an electrical conductor, would be "not connected to anything". I don't think that is what you meant. Could you elaborate.
Ed
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