generator transfer panel neutral wiring.

[jwelectric]

I have a listed piece of equipment. It has a UL label that is visible. Does this mean that I can use it in any manner that I see fit?

My piece of equipment is a two tube florescent light that I will be installing in a paint spray booth.

My point is simple, just because we have a transfer switch that has a UL label on it in no way means that we are installing it in the manner in which it was listed to be used. We cannot find anywhere in the NEC the installation instructions that are included with the listing of this equipment. In order to find the instructions included with the listing of the equipment we must go to the White Book.

In the UL White Book we will find that the type of generator that is being installed will play a huge role in which type of transfer switch that can be used. A good example of this is one of those transfer switches posted in this thread will not be acceptable for a self-contained stand-alone generator of less than 14KW. For more information see UL White Book Section FTCN.

 

[goldstar]

Mike,

I thought I'd post this from the 2010 White Book so everyone will know what you're talking about and so we're all on the same page. Would you please elaborate on the section you're talking about ?

ENGINE GENERATORS FOR PORTABLE USE (FTCN)

GENERAL
This category covers internal-combustion-engine-driven generators rated
15 kW or less, 250 V or less, which are provided only with receptacle outlets
for the ac output circuits. The generators may incorporate alternating or
direct-current generator sections for supplying energy to battery charging
circuits.

When a portable generator is used to supply a building wiring system:
1. The generator is considered a separately derived system in accordance
with ANSI/NFPA 70, ??National Electrical Code?? (NEC).

2. The generator is intended to be connected through permanently
installed Listed transfer equipment that switches all conductors other
than the equipment grounding conductor.

3. The frame of a Listed generator is connected to the equipment grounding
conductor and the grounded (neutral) conductor of the
generator. When properly connected to a premises or structure, the
portable generator will be connected to the premises or structure
grounding electrode for its ground reference.

4. Portable generators used other than to power building structures are
intended to be connected to ground in accordance with the NEC.

RELATED PRODUCTS
Engine generators intended for use in recreational vehicles are covered
under Engine Generators for Recreational Vehicles (FTCZ).

Engine generators intended for stationary use are covered under Engine
Generators (FTSR).

Wind-driven generators are covered under Wind Turbine Generating System
Subassemblies (ZGZJ).

Motor-generator sets and flywheel energy storage systems are covered
under Motor-Generator Sets (PQYW).

Generators, also referred to as generator heads or alternators, intended for
use in an engine generator are covered under Generators (JZGZ).

ADDITIONAL INFORMATION
For additional information, see Engine Generators (FTCA), Building Materials
(AABM) and Electrical Equipment for Use in Ordinary Locations (AALZ).

REQUIREMENTS
The basic standard used to investigate products in this category is UL
2201, ??Portable Engine-Generator Assemblies.??

UL MARK
The Listing Mark of Underwriters Laboratories Inc. on the product is the
only method provided by UL to identify products manufactured under its
Listing and Follow-Up Service. The Listing Mark for these products
includes the UL symbol (as illustrated in the Introduction of this Directory)
together with the word ?LISTED,? a control number, and the product name
??Engine Generator for Portable Use.??
* * * * * * * * * * * * * * * * * * * * * * * * *
UL, in performing its functions in accordance with its objectives, does not
assume or undertake to discharge any responsibility of the manufacturer or
any other party. UL shall not incur any obligation or liability for any loss,
expense or damages, including incidental or consequential damages, arising
out of or in connection with the use, interpretation of, or reliance upon this
Guide Information.

 

[jwelectric]

Many things come into play when doing electrical work. In NC we have the NC Electrical Code (NEC with amendments) as well as the laws and rules mandated by the NC licensing board and the Office of the State Fire Marshall.
Here in NC as well as many other states we cannot connect electrical equipment to homes or businesses unless the equipment is tested by a NRTL. 110.3(B) says that any equipment must be installed by any instructions that are included with the listing and labeling of that equipment.

I don?t think there is a member on this site that would argue that a strip light cannot be installed in a hazardous location even though the strip light contains an UL label.
I would also think that the reason that they would give is that the strip light is not listed for that type of installation.

What I am having a hard time accepting is why these same electricians cannot read this part of the listing of the stand-alone type of generator.

GENERAL
This category covers internal-combustion-engine-driven generators rated 15 kW or less, 250 V or less, which are provided only with receptacle outlets for the ac output circuits.

Here we are told that generators that are provided with receptacles for us to plug into in order to get power for anything.

When a portable generator is used to supply a building wiring system:
1. The generator is considered a separately derived system in accordance with ANSI/NFPA 70, ??National Electrical Code?? (NEC).

This statement clearly states that the transfer switch required by article 702 must switch the neutral. Those UL listed transfer switches posted in this thread does not switch the neutral and even though they have a UL label on them would be no more correct to use with one of these generators than the strip light that has a UL label being used in a hazardous location.

 

[Smart $]

... Those UL listed transfer switches posted in this thread does not switch the neutral and even though they have a UL label on them would be no more correct to use with one of these generators than the strip light that has a UL label being used in a hazardous location.

If I'm not mistaken (which is highly possible as I cannot find a schematic of the internal wiring), the Reliance models switch the neutral out of the circuit when on utility power.

 

[goldstar]

If I'm not mistaken (which is highly possible as I cannot find a schematic of the internal wiring), the Reliance models switch the neutral out of the circuit when on utility power.

Sorry Smart $, they do not. That was part of my reason for posing the question I did to begin with. JWElectric makes a good point with respect to why these generators should be considered separately derrived systems. However, neither Generac , B & G, Kohler, Reliance or any other manufactiurer are making transfer switches that switch the neutrals. So, now my question is "How is it that these manufacturers are able to sell and produce so many gen sets to the point that they are on back-order for months and ship them to all parts of the country where they are accepted by municipal officials except in NC ?" Do the manufacturers know something we don't ? They've based an entire marketing campaign on the fact that they can power your house during an outage. If JWElectric is correct then every gen set transfer switch manufactured to date is in violation of this UL standard.

 

[Smart $]

Sorry Smart $, they do not. That was part of my reason for posing the question I did to begin with. JWElectric makes a good point with respect to why these generators should be considered separately derrived systems. However, neither Generac , B & G, Kohler, Reliance or any other manufactiurer are making transfer switches that switch the neutrals. So, now my question is "How is it that these manufacturers are able to sell and produce so many gen sets to the point that they are on back-order for months and ship them to all parts of the country where they are accepted by municipal officials except in NC ?" Do the manufacturers know something we don't ? They've based an entire marketing campaign on the fact that they can power your house during an outage. If JWElectric is correct then every gen set transfer switch manufactured to date is in violation of this UL standard.

Don't forget we're only talking portable generators only. Permanently-installed generators can be either separately or non-separately derived systems. See 250.35.

Regarding portable generators, there is nothing in the NEC that says they have to be installed as separately derived systems... but if I'm in error, please correct me. Also see 250.34(A).

Also correct me if I'm wrong, generators (any) are not required to be Listed. So the listing actually creates the problem under 110.3(B).

 

[goldstar]

Don't forget we're only talking portable generators only. Permanently-installed generators can be either separately or non-separately derived systems. See 250.35.

I believe you are correct. However, I don't believe that any of the xfer switches manufactured or come packaged with these generators switches the neutral.

Regarding portable generators, there is nothing in the NEC that says they have to be installed as separately derived systems... but if I'm in error, please correct me. Also see 250.34(A).

Also correct me if I'm wrong, generators (any) are not required to be Listed. So the listing actually creates the problem under 110.3(B).

I'll let JWElectric take these two. He' the one that led the thread in this direction.

 

[jwelectric]

In North Carolina as well as several other states a generator cannot be connected to a premises wiring system unless it carries a label from a NRTL. The generator can be used all day long as a separate power source or a stand-alone power source not connected to a premises wiring system without a NRTL label.
What can?t be done is to use a stand-alone generator that has the receptacles mounted to the frame without having a bond between the EGC and the center tap of the winding of the generator.

If you understand how an overcurrent device works by having the EGC bonded to the neutral then understanding the floating neutral of a stand-alone power source will easy. It leaves the unit without a way to clear a fault. With a floating neutral in these generators a fault on the generator itself will energize the equipment grounding terminal of the receptacles causing a voltage difference between the EGC and the ungrounded conductor of the receptacle of 240 volts.
The GFCI device will continue to function as long as there is no imbalance of current between the grounded and ungrounded conductor.

All those transfer switches mentioned in this thread have their place but to connect a stand-alone power source is not one of them. Look at my scenario of the strip light. It carries a UL label so why can?t it be used in a spray paint booth?

Look closely at 250.34 and we see that it has a Note under it that says;

Informational Note: For grounding portable generators supplying fixed wiring systems, see 250.30.

Remember that in 250.34(A) we are not required to connect one of these to earth as long as we follow the two rules mentioned under this section. But if we connect them to the premises wiring then we must connect them to earth. Then in the handbook it goes on to explain this;

Portable and vehicle-mounted generators that are installed as separately derived systems and that provide a neutral conductor (such as 3-phase, 4-wire wye-connected; single-phase 240/120 volt; or 3-phase, 4-wire delta connected) are required to have the neutral conductor bonded to the generator frame.

There is always the question from some about 250.34(C) and the belief that this section allows the portable generator to be used as a non-separately derived system. This is not true. This section is in place to mandate that the devices mounted on the generator be installed in a code compliant manner. The question should be, ?can any branch circuit be installed with a floating neutral?? Do not the receptacles mounted on the frame of a self-contained generator fit the definition of a branch circuit?

We must also be aware that there are many generators out there both portable and mobile that do not have the receptacles mounted on the frame which can be used with the transfer switches outlined in this thread all day long as a non-SDS.

If this is not enough to clear up this issue take a look at 590.6(A)(3) of the 2011 cycle. When this is in full effect the connection using one of those transfer switches outlined in this thread will simply trip the GFCI device.

To clear up something, this is not my idea but is what is being taught by UL and the IAEI at the seminars and workshops through the country. I have been hearing this for a couple of years now.

 

[Smart $]

...

To clear up something, this is not my idea but is what is being taught by UL and the IAEI at the seminars and workshops through the country. I have been hearing this for a couple of years now.

I've not researched the listing prior to this discussion. I now agree with the teachings. It's not plainly evident looking only at the NEC, and likely not spelled out in many operation manuals.

 

[suemarkp]

But when you connect your portable generator to a house with a cord and transfer switch that doesn't switch the neutral (non-SDS approach), the main bonding jumper in the house handles the requirements of:

• Connecting the generator neutral to generator ground.
• Connecting the generator ground to a ground electrode system.
• Connecting the generator neutral to the generator frame

You're right the GFCI will become an issue if the gen receptacle you're using is GFCI protected and you connect it to a building with a main bonding jumper.

But it seems all the NEC rules you mentioned get fixed when you plug the generator into the house power inlet, even with a solid neutral transfer switch. Remove the cord and now you have a floating (unbonded) neutral, but that is ok because it is no longer a premises wiring system.

I also wonder if a NRTL will feel that have to verify to FTCN in order to give their "stamp of approval". We have similar rules here in WA for only connecting listed/NRTL equipment to building wiring systems. It was kind of interesting the things they (the test lab guys) focus on and what they don't. But I've never had them do a generator.

 

[GoldDigger]

You're right the GFCI will become an issue if the gen receptacle you're using is GFCI protected and you connect it to a building with a main bonding jumper.

But it seems all the NEC rules you mentioned get fixed when you plug the generator into the house power inlet, even with a solid neutral transfer switch. Remove the cord and now you have a floating (unbonded) neutral, but that is ok because it is no longer a premises wiring system.

I also wonder if a NRTL will feel that have to verify to FTCN in order to give their "stamp of approval". We have similar rules here in WA for only connecting listed/NRTL equipment to building wiring systems. It was kind of interesting the things they (the test lab guys) focus on and what they don't. But I've never had them do a generator.

I think that there is a potential problem in any case, even without the GFCI outlet at the generator, if the regulations applicable to the generator require both a ground to neutral bond and a local ground rod at the generator. What the testers want to see to provide safety for the unconnected generator or the generator powering only cord-connected equipment may not be compatible with what is needed when connect it to building wiring.

 

[Smart $]

I think that there is a potential problem in any case, even without the GFCI outlet at the generator, if the regulations applicable to the generator require both a ground to neutral bond and a local ground rod at the generator. What the testers want to see to provide safety for the unconnected generator or the generator powering only cord-connected equipment may not be compatible with what is needed when connect it to building wiring.

What the issue is IMO, is the potential for dual interconnection of grounding and grounded conductors. As qualified electricians, we can assure the generator's neutral and frame are unbonded and essentially wire as a non-SDS at time of installation. But being a "portable" generator that can still be used as such, there is no guarantee the user knows to or will rebond the neutral to the frame. Additionally, what if we are to wire up for a portable generator that isn't present at the time of installation. The customer wheels one up at a later date, switches over, and he has a parallel neutral path on the equipment ground.

 

[goldstar]

I think JWElectric has made a a lot of good points here. However, companies like Reliance, CH and others are still producing panels like this one :

http://www.electricgeneratorsdirect.com/product-images/30310AK_New_500.jpg

So, irrespective of whether anyone thinks JWElectric is correct or not (and I happen to think he is), as long as these xfer panels are being produced they will be installed, perhaps not by those who are getting an education here in the Forum but by many across the country. I think the education process has to start with the manufacturer and not with the installer. Just my opinion.

Here's another product on the market that I have recently installed for several people :

http://www.generator-switch.com/

This unit transfers both the individual branch circuit hot and neutral wiring. Now, in accordance with our discussion here, if I locate this switch at the boiler location I would be Code compliant. I would be interrupting the premise wiring and connecting directly to the boiler circuitry by the flip of a switch. I would then have to drag an extension cord through the house to wherever the boiler is (not sure if that is the safest thing). On the other hand, if I locate the unit adjacent to the breaker panel in the garage and wire it in there I would be in violation because I would be using the premise wiring to power the boiler.

The other thing that has to be considered is that in dire emergencies people will go to great lengths to provide (just about anything) for their families. I can't begin to tell you about some of the "Rube Goldbergs" that I've seen during the last super storm and power outage. People can last a day or so without power. When it goes into days or weeks - that's a different story. Even though panels like the ones cited above may not be UL compliant they're a lot better than shutting off your main breaker and back-feeding the house through your spa tub or AC disconnect.

Again, just my 2 cents worth.:roll:

 

[jwelectric]

People are going to do what people are going to do and no matter what kind of switch is available won?t change this.

I heard someone compare this argument to the game people with a wheel gun, putting only one shell in is far safer than putting in three, four, or five would be. It won?t much matter how many are loaded when the hammer falls on just one shell.

Yes people will do whatever it takes when faced with extreme conditions but compliant is compliant and as an electrical contractor what I install must the safe and compliant.
I cannot justify doing something that is non-compliant and making the remark that it is far safer than what I saw someone do last week.

The trip hazard of a cord is far less a safety hazard than electrocution or fire due to a non-compliant installation. During power outages at my home we have a couple of cords to supply temp power to lights and sometimes to the frig and freezer. These cords don?t lie around all day long.

For the most part those connecting one of these generators to their homes will also be watching TV which anyone of us could do without for a period of time. I can watch my great grand children and don't need a TV to do this for me.

 

[goldstar]

People are going to do what people are going to do and no matter what kind of switch is available won?t change this.

Yes people will do whatever it takes when faced with extreme conditions but compliant is compliant and as an electrical contractor what I install must the safe and compliant.
I cannot justify doing something that is non-compliant and making the remark that it is far safer than what I saw someone do last week.

I'm not saying you're wrong. All I'm saying is that as long as these devices are being produced and marketed the way they are - they will be installed. If there are 100 EC's in a given area and 100 AHJ's and those 100 AHJ's are approving these installations, and if you're the one contractor that says this is in violation of a UL standard then you'll be the one collecting the welfare check.

Until we can get ourselves educated to a point where the vast majority of AHJ's are knocking the installation of these things down and/or manufacturers stop making and marketing these devices the way they do they will continue to be installed.

 

[stew]

Seems to me this thread has gotten way off the mark or something. All I wanted to know was when you have to wire between a subpanel used as a manual gen transfer panel or any other panel like Reliance,Genrac,that is used as a subpanel/manual transfer device when you bring the circuit conductors over from the exisiting main panel to the sub do you have to run separate neutrals for each circuit conductor or could you just pull a large neutral in the pipe or raceway. Separate egcs are not required so long as you pull one in each raceway equivalent to the largest load in that raceway if using flex or nmflex. Code tells us that we need to run a neutral with the circuit conductors but my question was is a separate neutral needed for each circuit conductor or one large neutral in each raceway? Just had an install where I had to run up over a doorway to an adjacent wall to mount the sub. Little trickey getting all the wire over with derating and such. had 7 15 amp circuits,5 20 amp circuits,one 30 amp circuit, the main power to the sub,and the 30 amp circuit from the outdoor outlet back over to the subpanel gen breaker to contend with.

The thread seemed to have diverged from the original question or did I miss something.

 

[jwelectric]

I think that the thread stayed on topic depending on the type of generator you are installing. If it is a cord and plug installation for a generator that has receptacles mounted on the frame of the generator then the installation you are questioning wouldn?t matter as the total installation would be non-compliant.

For a general answer to your question see 200.4 of the 2011

 

[Smart $]

...

The thread seemed to have diverged from the original question or did I miss something.

Putting the diverged issues aside, the most succinct answer I can give is, once the circuits are down to branch circuit level, you cannot re-combine those neutrals into one larger one.

Use to be you could run one larger neutral from the originating panel... but no more.

 

[goldstar]

Seems to me this thread has gotten way off the mark or something. All I wanted to know was when you have to wire between a subpanel used as a manual gen transfer panel or any other panel like Reliance,Genrac,that is used as a subpanel/manual transfer device when you bring the circuit conductors over from the exisiting main panel to the sub do you have to run separate neutrals for each circuit conductor or could you just pull a large neutral in the pipe or raceway. Separate egcs are not required so long as you pull one in each raceway equivalent to the largest load in that raceway if using flex or nmflex. Code tells us that we need to run a neutral with the circuit conductors but my question was is a separate neutral needed for each circuit conductor or one large neutral in each raceway? Just had an install where I had to run up over a doorway to an adjacent wall to mount the sub. Little trickey getting all the wire over with derating and such. had 7 15 amp circuits,5 20 amp circuits,one 30 amp circuit, the main power to the sub,and the 30 amp circuit from the outdoor outlet back over to the subpanel gen breaker to contend with.

The thread seemed to have diverged from the original question or did I miss something.

If you're using this type automatic transfer switch/sub-panel : http://www.electricgeneratorsdirect.com/Images/Generac-Guardian-RTS16EZA1/i4828.html with a UL listed generator that it's paired with, the neurtals have to originate in the panel the branch circuits are fed from.

If you're using this type manual transfer panel : http://www.electricgeneratorsdirect.com/Images/Reliance-Controls-51410C/i1127.html with a portable generator the design is such that, while on utility power, the branch circuits are still being fed from the panel they originate in. The individual switches serve to switch each ungrounded branch circuit conductor from the breaker panel onto the generator. The neurtal is back-fed from the generator to the neutral bar of the breaker panel.

Now, as JWElectric pointed out this is not considered a Code compliant installation.