manual transfer switch

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Jraef said:
Plug-in breakers that are used as back-fed must be held in place so that in the even of a fault, the mechanical forces do not pull it off the bus.
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Utility interactive PV (solar) backfed breakers are exempted from this requirement.
 
kwired said:
Forget some of code for the moment - when connecting to premises wiring with utility supply the bond is intended to be at the service equipment.

If you run separate ground and grounded conductors from generator that is bonded you will have parallel path for grounded conductor.

Ideally you want non bonded generator and the bond at the service equipment. Then the generator frame and any paths in between won't be carrying any current during normal use.

A smaller portable with no bond is just an ungrounded system when using for portable power. Unlike a utility system that is well grounded - even if you fail to ground your service correctly there is still voltage to ground because of the large grounding network that is inherent to the utility system. But this small isolated source has no ground reference. So a first ground fault is not really much of a hazard to users, it simply becomes a grounded system at this point, though not at the conventional point of the system. No fault current flows until there is a second fault. A GFCI receptacle on the generator still protects you from potential shock hazards - current still has to flow outside the protected circuit to trip, though potential for having current flowing outside that circuit is greatly lessened by not having a stout ground reference like a utility supply has.
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Thanks for the reply. Okay, I see what you're saying regarding the theory behind it. I guess I thought maybe I was missing something that maybe the engineers behind the generators understand that I don’t. I spoke with a large distributor of portable generators who said he’s never had a problem with local authorities and a bonded neutral being used on an interlock device. And I also had spoken with a manufacturer before who said it’s fine to do. And I also see mostly bonded portable generators for sale that I know are being hooked up without the knowledge of a floating vs bonded neutral. Also, the manuals don’t really say much on warning a user about this matter. So, I guess I understand the theory and I am aware of article 250.6, but just thought maybe I was missing something. If someone wants an interlock device on their panel, what are they plugging into the inlet? I don't see a lot of "floating neutral" generators. What do you do out there or recommend?
 
I HAVE ONLY ONE METER 400 AMPS SERVICES TWO PANEL 200 AMPS
WE ARE GOING TO INSTALL TWO TRANSFER SWITCH (ATS)(GENERAC) WITH ONLY ONE GENERATOR
QUESTION
CAN I RUN LOAD AND CONTROL WIRES IN PARALLEL? OR I MEAN PUT A WIREWAYS BOX ON FRONT OF GENERATOR AND FEED GENERATOR FROM?
 
and!ru said:
Thanks for the reply. Okay, I see what you're saying regarding the theory behind it. I guess I thought maybe I was missing something that maybe the engineers behind the generators understand that I don’t. I spoke with a large distributor of portable generators who said he’s never had a problem with local authorities and a bonded neutral being used on an interlock device. And I also had spoken with a manufacturer before who said it’s fine to do. And I also see mostly bonded portable generators for sale that I know are being hooked up without the knowledge of a floating vs bonded neutral. Also, the manuals don’t really say much on warning a user about this matter. So, I guess I understand the theory and I am aware of article 250.6, but just thought maybe I was missing something. If someone wants an interlock device on their panel, what are they plugging into the inlet? I don't see a lot of "floating neutral" generators. What do you do out there or recommend?
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If you have generator that is bonded but has no gfi protection
Your code violation is 2 neutral to ground bonds in a system where only 1 is allowed. And you could have a problem with neutral current on the ground.
If you have a generator that is bonded and it has gfi protection it will trip the gfi if the system you are powering is also bonded.
That is why you take the bond loose in the generator or switch you neutral in the MTS.
I personally have a bonded generator that has no gfi protection and I have no problem using it like that. If it had gfi protection I would have no problem taking the bond loose even though the code says you can't modify a listed piece of equipment. I would just mark it to let everyone know it was unbounded and meant for backup power only to a bonded system.
I also have no problem using an interlock kit that is not UL listed even though a lot of inspectors do have a problem with them.
But that's just me.
 
qcroanoke said:
If you have generator that is bonded but has no gfi protection
Your code violation is 2 neutral to ground bonds in a system where only 1 is allowed. And you could have a problem with neutral current on the ground.
If you have a generator that is bonded and it has gfi protection it will trip the gfi if the system you are powering is also bonded.
That is why you take the bond loose in the generator or switch you neutral in the MTS.
I personally have a bonded generator that has no gfi protection and I have no problem using it like that. If it had gfi protection I would have no problem taking the bond loose even though the code says you can't modify a listed piece of equipment. I would just mark it to let everyone know it was unbounded and meant for backup power only to a bonded system.
I also have no problem using an interlock kit that is not UL listed even though a lot of inspectors do have a problem with them.
But that's just me.
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So you don't use a MTS that switches the neutral for your generator (that has a bonded neutral)?
 
and!ru said:
It seems like u could have a little or a lot of current ending up on the ground wire depending on how balanced your loads are. Have u ever measured? Wouldn't it be a safety concern?
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If the only thing between the generator and the transfer switch is a rubber cord you don't have any neutral current on anything un-insulated so the hazard is not that big.
 
ActionDave said:
If the only thing between the generator and the transfer switch is a rubber cord you don't have any neutral current on anything un-insulated so the hazard is not that big.
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Okay, I see. But if the neutral wire is damaged then the current is on the ground wire which wouldn't be sized to carry the current.
 
and!ru said:
Okay, I see. But if the neutral wire is damaged then the current is on the ground wire which wouldn't be sized to carry the current.
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In the smaller cordsets the ground is often the same size as the grounded and ungrounded conductors for the size generator we're talking about
 
qcroanoke said:
In the smaller cordsets the ground is often the same size as the grounded and ungrounded conductors for the size generator we're talking about
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I know for example the 50 amp cords have a #8 ground wire. I know that’s still large enough to carry the neutral load. But being that it would have a few more splices along it’s path and possibly landed on a ground bar (connected to the can, which could add a little more resistance) and not the neutral bar. It doesn’t seem like it would have a clean return like the neutral. If the neutral wire broke you’d never know and the connection points could overheat?
 
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