confused about generators

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I'm eliminating EGCs from the discussion for a second since they only exist for a fault clearing path.

So you have two hots from the utility on one side of the transfer switch and two hots from the generator on the other side of the transfer switch. You have one neutral from the utility and one neutral from the generator landing on a common buss in the transfer switch. Electrons are only flowing from the generator to the load and back to the generator source neutral or they are flowing from the utility to the load and back on the utility source neutral. There is never any parallel neutral current on any neutral wires if everything is wired properly.

Unlessss you have a second neutral bond somewhere in the system. Then you could possibly have some neutral current flowing on some metal parts trying to get to its respective source.
 
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phatso86 said:
I wanted to keep the diagram as simple as possible.
I picked arbitrary amperes for the circuits. The issue is the current going from the main panel back to the sub panel.
this is the set up that transfer switch manuals say to implement in the system
Click to expand...
Your main panel is nothing more than a junction box for the branch circuits in question now. If this were new installation you should run the branch circuits directly to the standby panel. For retrofits to existing people do something similar to what you have drawn.

Some say you must run the branch circuit neutrals back to the "subpanel" that the ungrounded conductors originate from, some say you don't - depending on some details of how it is done. At very least you don't want them installed in a way that they are in parallel with the feeder neutral conductor to that panel.

If you have any AFCI's or GFCI breakers involved you don't have much choice but to bring the branch circuit neutral to the branch circuit breaker with no interconnection to any other neutral conductor or it will cause device to trip.
 
kwired said:
Your main panel is nothing more than a junction box for the branch circuits in question now. If this were new installation you should run the branch circuits directly to the standby panel. For retrofits to existing people do something similar to what you have drawn.

Some say you must run the branch circuit neutrals back to the "subpanel" that the ungrounded conductors originate from, some say you don't - depending on some details of how it is done. At very least you don't want them installed in a way that they are in parallel with the feeder neutral conductor to that panel.

If you have any AFCI's or GFCI breakers involved you don't have much choice but to bring the branch circuit neutral to the branch circuit breaker with no interconnection to any other neutral conductor or it will cause device to trip.
Click to expand...


well that makes sense. I would simply wirenut the neutrals at the main panel, I just couldn't figure out if it is "wrong" to disobey the transfer switch manual (meaning it won't operate correctly).

I guess I can ask the city inspector if the condition I presented parallels the neutrals
 
phatso86 said:
well that makes sense. I would simply wirenut the neutrals at the main panel, I just couldn't figure out if it is "wrong" to disobey the transfer switch manual (meaning it won't operate correctly).

I guess I can ask the city inspector if the condition I presented parallels the neutrals
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Do they connect to the "supply" neutral conductor in more than one place? If not there is no possible way they are parallel to the supply neutral.
 
kwired said:
Your main panel is nothing more than a junction box for the branch circuits in question now. If this were new installation you should run the branch circuits directly to the standby panel. For retrofits to existing people do something similar to what you have drawn.

Some say you must run the branch circuit neutrals back to the "subpanel" that the ungrounded conductors originate from, some say you don't - depending on some details of how it is done. At very least you don't want them installed in a way that they are in parallel with the feeder neutral conductor to that panel.

If you have any AFCI's or GFCI breakers involved you don't have much choice but to bring the branch circuit neutral to the branch circuit breaker with no interconnection to any other neutral conductor or it will cause device to trip.
Click to expand...

Just to backup what Kwired has said, my recommendation is to run a neutral wire with each branch circuit hot (both wires in the same cable or conduit) from the main panel wirenut connection to the subpanel. Then land these neutrals on the subpanel neutral bar unless they go to a GFCI or AFCI breaker. The cable or conduit for the feeder from the main panel breaker to the subpanel must contain the neutral return wire for the feeder, be sized appropriately, and connect the neutral bars of both main and subpanels together. This way the currents through the hot and neutral wires of each circuit are kept close together, minimizing AC magnetic fields.

If I'm interpreting your diagram correctly there are (in this case) two branch circuit sized neutral conductors connecting the neutral bars of subpanel and main panel, as well as a feeder neutral. If so, this is not only redundant but it can be dangerous. If the feeder neutral gets disconnected then the smaller neutrals are susceptible to overloading.
 
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synchro said:
Just to backup what Kwired has said, my recommendation is to run a neutral wire with each branch circuit hot (both wires in the same cable or conduit) from the main panel wirenut connection to the subpanel. Then land these neutrals on the subpanel neutral bar unless they go to a GFCI or AFCI breaker. The cable or conduit for the feeder from the main panel breaker to the subpanel must contain the neutral return wire for the feeder, be sized appropriately, and connect the neutral bars of both main and subpanels together. This way the currents through the hot and neutral wires of each circuit are kept close together, minimizing AC magnetic fields.

If I'm interpreting your diagram correctly there are (in this case) two branch circuit sized neutral conductors connecting the neutral bars of subpanel and main panel, as well as a feeder neutral. If so, this is not only redundant but it can be dangerous. If the feeder neutral gets disconnected then the smaller neutrals are susceptible to overloading.
Click to expand...
It also seems to be a clear violation of the parallel conductors rule.
 
synchro said:
Just to backup what Kwired has said, my recommendation is to run a neutral wire with each branch circuit hot (both wires in the same cable or conduit) from the main panel wirenut connection to the subpanel. Then land these neutrals on the subpanel neutral bar unless they go to a GFCI or AFCI breaker. The cable or conduit for the feeder from the main panel breaker to the subpanel must contain the neutral return wire for the feeder, be sized appropriately, and connect the neutral bars of both main and subpanels together. This way the currents through the hot and neutral wires of each circuit are kept close together, minimizing AC magnetic fields.

If I'm interpreting your diagram correctly there are (in this case) two branch circuit sized neutral conductors connecting the neutral bars of subpanel and main panel, as well as a feeder neutral. If so, this is not only redundant but it can be dangerous. If the feeder neutral gets disconnected then the smaller neutrals are susceptible to overloading.
Click to expand...

I can't make sense of what you are saying. The first half of your post is crazy, and I don't know why someone would ever wire this way. You don't run feeder wires and branch circuit wires between panels.

The second half of your post contradicts the first half.
 
ActionDave said:
I can't make sense of what you are saying. The first half of your post is crazy, and I don't know why someone would ever wire this way. You don't run feeder wires and branch circuit wires between panels.
Click to expand...


Maybe I just succeeded in confusing the issue instead of clarifying it:

synchro said:
Just to backup what Kwired has said, my recommendation is to run a neutral wire with each branch circuit hot (both wires in the same cable or conduit) from the main panel wirenut connection to the subpanel. Then land these neutrals on the subpanel neutral bar unless they go to a GFCI or AFCI breaker.
Click to expand...

^ This was just my (apparently poor) way of restating what kwired said about taking the branch circuit conductors (originally connected to the main panel breakers) and connecting them to new wires that are fed by the subpanel branch breakers. This connection would be the "wirenutting" mentioned by the OP. As kwired said, the main panel would just be a junction box for this connection:

kwired said:
Your main panel is nothing more than a junction box for the branch circuits in question now. If this were new installation you should run the branch circuits directly to the standby panel. For retrofits to existing people do something similar to what you have drawn.
Some say you must run the branch circuit neutrals back to the "subpanel" that the ungrounded conductors originate from, some say you don't - depending on some details of how it is done
.
Click to expand...
Also, I was recommending the option kwired mentioned above to "run the branch circuit neutrals back to the "subpanel" that the ungrounded conductors originate from" in order to keep these neutrals with their corresponding branch ungrounded conductors as much as possible to minimize the loop area between them. This minimizes magnetic fields induced in metal panels and conduits.



synchro said:
If I'm interpreting your diagram correctly there are (in this case) two branch circuit sized neutral conductors connecting the neutral bars of subpanel and main panel, as well as a feeder neutral. If so, this is not only redundant but it can be dangerous. If the feeder neutral gets disconnected then the smaller neutrals are susceptible to overloading.
Click to expand...

^ This is echoing what kwired said about not having parallel connections of the neutral conductors:

kwired said:
Some say you must run the branch circuit neutrals back to the "subpanel" that the ungrounded conductors originate from, some say you don't - depending on some details of how it is done. At very least you don't want them installed in a way that they are in parallel with the feeder neutral conductor to that panel.
Click to expand...
 
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synchro said:
If I'm interpreting your diagram correctly there are (in this case) two branch circuit sized neutral conductors connecting the neutral bars of subpanel and main panel, as well as a feeder neutral. If so, this is not only redundant but it can be dangerous. If the feeder neutral gets disconnected then the smaller neutrals are susceptible to overloading.
Click to expand...

yes, you described it exactly how I tried to draw it.
Didn't think about it becoming a dangerous condition, duly noted.
Thank you
 
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