Portable Generators and GFCIs 2011 NEC

[electricmanscott]

PG = portable generator

Assumed you could figure that out being we are discussing them.


I

You and I both know he knows exactly what it means. This is Mikes way of belittling you.

I don't even have to read the thread to know what is going on here. I learned a long time ago to walk away when Mike jumps in. You'd be wise to do the same.

 

[iwire]

You and I both know he knows exactly what it means. This is Mikes way of belittling you.

I don't even have to read the thread to know what is going on here. I learned a long time ago to walk away when Mike jumps in. You'd be wise to do the same.

Great advice, I should follow it myself.

 

[Smart $]

Well now you sure have found something in you code book that I can?t find in mine. Which year are you using? Just where does it require to be connected to earth in 250.34??

2008, and AFAIK, 2011 is the same. Perhaps the more direct approach will work...

250.34(C) Grounded Conductor Bonding. A system conductor
that is required to be grounded by 250.26 shall be connected
to the generator frame where the generator is a component
of a separately derived system.

In the 2008 code cycle there was a change in the language in 250.34 for clarification on the frame of portable generators and their relationship to earth. Frames of portable generators are not an electrode and the portable generator is not required to be connected to a grounding electrode. The portable generator is an ungrounded standalone electrical system just as the slide I posted states.

My response above should have cleared your misconception up...

Unless this portable generator is in the basement I would say that it is outside. If it is outside then any and all wiring to and from would fall under 225. I thought you knew that we were talking about outside PGs.

I have been and will continue to assume the generator to be outside. Is there something specific in 225 that you are dwelling on it?

Any conductor that is on the supply of the bonding jumper IS NOT an equipment grounding conductor!!

Equipment grounding conductors are sized on Table 250.122 and are sized based on the size of the overcurrent device protecting the ungrounded conductors.

I'll let these ride for now...

The Supply Side Bonding Jumper is the conductor between the generator and the first disconnect at the building being served when the generator is being installed as a non-separately derived system and is sized using Table 250.66 The name changed in the 2011 cycle but the method of sizing is still the same. Before 2011 it was called the equipment bonding conductor.

If the generator is connected non-SDS, there can't be an SSBJ. Look under 250.24 Grounding Service-Supplied Alternating-Current Systems and tell me where you see an SSBJ requirement. SBJ's are for SDS systems, which the generator is not in this case.

In the case where the generator is a component of an SDS, the bonding jumper (SSBJ if you will) is between the generator and the first disconnecting means... and that is the breaker on the generator!!! So where ya' gonna put this jumper and where does it spell it out in 250.30? The only thing I see required is in 250.34(C). And you keep referring to the note, but we all know that notes aren't enforceable... so please enlighten me, 'cause from my point of view you have failed to so far.

Anyway... long day here, so at this point, I'm going to table responding to the balance of your post...

 

[Smart $]

You and I both know he knows exactly what it means. This is Mikes way of belittling you.

But I'll let him believe I don't know that he knows... drat, gave it away :roll:

I hope he thinks he's succeeding. One of my premises in life is to help others as best I can.

I don't even have to read the thread to know what is going on here. I learned a long time ago to walk away when Mike jumps in. You'd be wise to do the same.

Great advice, I should follow it myself.

Well, I suppose I will when I have something more entertaining to do...

 

[jwelectric]

I hope he thinks he's succeeding. One of my premises in life is to help others as best I can.

This is something that I set out to do 10 years ago and hope to have at least 10 more years in me doing the same thing.

 

[jwelectric]

2008, and AFAIK, 2011 is the same. Perhaps the more direct approach will work... My response above should have cleared your misconception up...

I have been and will continue to assume the generator to be outside. Is there something specific in 225 that you are dwelling on it?

I made a post that once that a generator becomes attached to premises wiring that the generator is no longer portable (post #9) and you and Bob came back with a comment looking for proof of my statement.
I know that Bob is pretty smart so I figured by the way he asked the question (post #19) he already knew the definition of premises wiring so I took a different approach as I many time do just for fun and thus all this with you has transpired.

Any generator that is connected to the premises wiring system becomes part of that system as outlined in the definition of premises wiring. So any time any generator becomes connected to the building it is no longer portable or should I say is no more portable than what ever it is connected to is portable.

As anyone who knows me will tell you and Scott has pointed out I will continue something like this until we have covered the entire code book before relenting.

The answer to the portable generator being used as an optional stand by system is found in Part III of 702 and nobody mentioned this in this complete thread. Is this because they didn?t know or was too wrapped up in my sick sense of humor?

But your statement that 250.34 requires a portable generator to be connected to earth is way off base.

250.34 Portable and Vehicle-Mounted Generators.
(A) Portable Generators. The frame of a portable generator shall not be required to be connected to a grounding electrode as defined in 250.52 for a system supplied by the generator under the following conditions:
(1) The generator supplies only equipment mounted on the generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and
(2) The normally non?current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are connected to the generator frame.
(B) Vehicle-Mounted Generators. The frame of a vehicle shall not be required to be connected to a grounding electrode as defined in 250.52 for a system supplied by a generator located on this vehicle under the following conditions:
(1) The frame of the generator is bonded to the vehicle frame, and
(2) The generator supplies only equipment located on the vehicle or cord-and-plug-connected equipment through receptacles mounted on the vehicle, or both equipment located on the vehicle and cord-and-plug-connected equipment through receptacles mounted on the vehicle or on the generator, and
(3) The normally non?current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are connected to the generator frame.
(C) Grounded Conductor Bonding. A system conductor that is required to be grounded by 250.26 shall be connected to the generator frame where the generator is a component of a separately derived system.
FPN: For grounding portable generators supplying fixed wiring systems, see 250.20(D).

This Note was changed in 2011 with 250.20(D) being deleted and 250.30 added in it?s place.

Here is a slide from the 2008 Analysis of changes

Notice that this portable generator is an ungrounded system. This means that is has no earth connection.
Here is part of page 90 of the 2008 Analysis of changes that clears up any confusion about a portable generator and an earth connection.

There is no requirement to connect a portable generator to earth UNLESS someone decides to use this as an optional standby system.

The new requirement found in 590 that all receptacles under 14kw are to be GFCI protect will insure that when this portable generator is connected as an optional standby system the neutral will be switched or the GFCI device will open. Or in other words this Ungrounded Portable Generator can no longer be connected to a premises wiring system as a Non-Separately Derived System.
There is also a new section 250.30(C) that covers the grounding when installing this Ungrounded Portable Generator to premises wiring.

To answer your question concerning ARTICLE 225 Outside Branch Circuits and Feeders, the conductors from that generator and the premises wiring are just as outlined in the title of this article, they are outside making this article prudent to the installation especially Part II.

 

[Smart $]

I made a post that once that a generator becomes attached to premises wiring that the generator is no longer portable (post #9) and you and Bob came back with a comment looking for proof of my statement.

I know that Bob is pretty smart so I figured by the way he asked the question (post #19) he already knew the definition of premises wiring so I took a different approach as I many time do just for fun and thus all this with you has transpired.



Any generator that is connected to the premises wiring system becomes part of that system as outlined in the definition of premises wiring. So any time any generator becomes connected to the building it is no longer portable or should I say is no more portable than what ever it is connected to is portable.

Well, I read your words and understand your perspective... but I respectfully disagree.

Put a portable generator on a property that has no other source of electrical power and by the definition of a premises wiring (system) in Article 100, that PG is a premises wiring system. The NEC even dedicates Article 445 to the installation of generators. We've even been discussing a specific section on their grounding. Now one might ask: how do I install a portable generator? ...Well you simply plop it down wherever convenient and start it up.

As anyone who knows me will tell you and Scott has pointed out I will continue something like this until we have covered the entire code book before relenting.

I surmised such. Knock yourself out... but don't expect me to get all wordy in reply.

The answer to the portable generator being used as an optional stand by system is found in Part III of 702 and nobody mentioned this in this complete thread. Is this because they didn?t know or was too wrapped up in my sick sense of humor?

And look at the Scope therein...

702.1 Scope. The provisions of this article apply to the
installation and operation of optional standby systems.
The systems covered by this article consist of those that
are permanently installed in their entirety, including prime
movers, and those that are arranged for a connection to a
premises wiring system from a portable alternate power
supply.

So even here we have a statement which supports the concept that portable source remains portable even while connected.

But your statement that 250.34 requires a portable generator to be connected to earth is way off base.

(code citation removed by me for brevity)

It's not hard to understand. 250.34(C) says when connected to a system conductor required to be grounded, the frame must be bonded to the grounded conductor. If the mentioned grounded conductor is grounded as required, then how can the generator not be grounded?

Here is a slide from the 2008 Analysis of changes
...
Notice that this portable generator is an ungrounded system. This means that is has no earth connection.

I agree. As pictured it is not grounded.

Here is part of page 90 of the 2008 Analysis of changes that clears up any confusion about a portable generator and an earth connection.

Well, the analysis doesn't clear up anything for me... as there is nothing to clear up from my perspective.

There is no requirement to connect a portable generator to earth UNLESS someone decides to use this as an optional standby system.

I agree.

The new requirement found in 590 that all receptacles under 14kw are to be GFCI protect will insure that when this portable generator is connected as an optional standby system the neutral will be switched or the GFCI device will open. Or in other words this Ungrounded Portable Generator can no longer be connected to a premises wiring system as a Non-Separately Derived System.

Have to disagree. You are assuming the frame to grounded conductor connection required by 250.34(C) is not removed. What would trip the GFCI's (other than a real ground fault) would be some of the ungrounded conductor current not returning on the grounded neutral conductor... because instead it returns on the grounding conductors, for they are essentially a parallel path. As such, the frame to grounded neutral conductor connection can be eliminated under 250.6(A) and (B) for a non-SDS connection.

There is also a new section 250.30(C) that covers the grounding when installing this Ungrounded Portable Generator to premises wiring.

...and 250.30 covers SDS's. Show me code that actually says a PG cannot be connected non-SDS.

To answer your question concerning ARTICLE 225 Outside Branch Circuits and Feeders, the conductors from that generator and the premises wiring are just as outlined in the title of this article, they are outside making this article prudent to the installation especially Part II.

Oh I know the Article is pertinent to installation, but thanks for the reminder