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Author Topic: Portable Generator Neutral Bonding  (Read 13552 times)

Mike Sokol

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Portable Generator Neutral Bonding
« on: June 29, 2014, 07:11:06 am »

I just found a really good list of hundreds of portable generators which shows if they have bonded or floated neutrals. http://www.generlink.com/CompatibleGenerator.pdf

In summary: If a portable generator already has a bonded neutral, then the only thing you need to do for outdoor stage use is drive a ground rod and attach it to the generator's ground lug. However, a generator with a floated neutral should also be G-N bonded to provide a direct fault path back to the power source in the event of a Line-to-Chassis short in a piece of stage gear. In addition to that, any metal stage structure should also be bonded to the generator's earth grounding point to prevent differential voltages between stage metal and an amplifier chassis which would cause a shock hazard to musicians and stage technicians.

I think the above statement is pretty logical. However, if any of you feel it should be edited for clarity or content, please add to the discussion.   
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Cailen Waddell

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Re: Portable Generator Neutral Bonding
« Reply #1 on: June 29, 2014, 09:07:08 am »

This should be a sticky...


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Mark Cadwallader

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Re: Portable Generator Neutral Bonding
« Reply #2 on: June 29, 2014, 01:49:17 pm »

This should be a sticky...


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Yes. Mike, if you do, please add a note urging users to check the revision date on the link. Mark C.
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frank kayser

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Re: Portable Generator Neutral Bonding
« Reply #3 on: June 29, 2014, 02:06:14 pm »

I just found a really good list of hundreds of portable generators which shows if they have bonded or floated neutrals. http://www.generlink.com/CompatibleGenerator.pdf

In summary: If a portable generator already has a bonded neutral, then the only thing you need to do for outdoor stage use is drive a ground rod and attach it to the generator's ground lug. However, a generator with a floated neutral should also be G-N bonded to provide a direct fault path back to the power source in the event of a Line-to-Chassis short in a piece of stage gear. In addition to that, any metal stage structure should also be bonded to the generator's earth grounding point to prevent differential voltages between stage metal and an amplifier chassis which would cause a shock hazard to musicians and stage technicians.

I think the above statement is pretty logical. However, if any of you feel it should be edited for clarity or content, please add to the discussion.

Mike,
Clarification, please.
Statement 1 (red) makes sense.
Statement 2 (blue) is completely separated from statement one by "However"

As it is in the same paragraph, and follows statement two without qualification, it appears that the bonding of the metal stage applies only to statement two (unbonded generators, subsequently bonded by end user)

For clarity, (the way I understand it - which may be incorrect) I think maybe three separate statements are in order:

1. For the outdoor stage, using a portable generator already having a bonded neutral, then one needs to
 drive a ground rod and attach it to the generator's ground lug.

2. For the outdoor stage, using a generator with a floated neutral,
- the user should bond G-N at the generator (link to your magic bonding plug here) to provide a direct fault path back to the power source in the event of a Line-to-Chassis short in a piece of stage gear.
- one needs to drive a ground rod and attach it to the generator's ground lug

3. For either type of generator, any metal stage structure should also be bonded to the generator's earth grounding point to prevent differential voltages between stage metal and an amplifier chassis which would cause a shock hazard to musicians and stage technicians.


Might wish to make a statement on the safety concerns of driving a ground rod (underground utilities?)   

Ok.  One problem solved.  Statements are separate and "clear" (to my reading and mind).
-----------------------------------------
Second clarification (off topic slightly, with apologies)
Assuming the same metal stage, does statement 3 hold true using shore power (connecting metal stage to safety ground, not a ground rod)

-----------------------------------------
And please correct me if I am wrong, on that particular stage, as an example, it would be unwise (unsafe) to run the PA off a genset, and the backline off shore power.  Either all genset or shore power..

thanks
frank
« Last Edit: June 29, 2014, 02:12:46 pm by frank kayser »
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Frank DeWitt

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Re: Portable Generator Neutral Bonding
« Reply #4 on: June 29, 2014, 04:24:43 pm »

Note, when paralleling two Honda EU series inverter generators with the Honda parallel kit with no mods the two generators will have there frames connected and the ground terminal of the outlets will be connected, but the grounds are not connected to the neutral.  The parallel package from Honda doesn't color code the plugs so the "neutral" (Wide slot) on one generator outlet can be connected to the "Hot" (narrow slot) on the other generator.

There are ways to insure that the neutral is connected to the neutral such as colored tape or paint but this is not recommended.
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Lyle Williams

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Re: Portable Generator Neutral Bonding
« Reply #5 on: June 29, 2014, 04:44:51 pm »

Down here in Australia floated neutral generators are designed/approved to power a single load only.  Of course, that's not what occurs in the real world.  People add power strips and run cables everywhere.

But with a single load only there are safety arguments for keeping the floated neutral.
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jasonfinnigan

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Re: Portable Generator Neutral Bonding
« Reply #6 on: June 29, 2014, 05:07:20 pm »

Question the generator I use a lot is the lincoln electric Commander 500 and also the Ranger 250 GXT we use it for smaller stuff, Just says unit is too large. What does that mean? We tied to the ground but does that mean I need to tie the rod to neutral as well? The rental house takes care of these as well as the larger Kolher generators we rent but I want to make sure they are doing it right.
« Last Edit: June 29, 2014, 05:13:11 pm by JasonFinnigan »
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Mike Sokol

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Re: Portable Generator Neutral Bonding
« Reply #7 on: June 29, 2014, 05:32:04 pm »

BTW: I'm going to try my bed-o-nails "Sokol Ground" later this week. My plan is to install it in the corner of my yard and run a fall of potential test under various wet and dry conditions. That way I can see if it's a viable solution at all and gather some empirical data as to its actual ground impedance. If by chance it comes in under 100 ohms under standard soil conditions, I'm going to petition the NEC committee for a variance to allow it for portable generator use. We shall see if it works or I'm barking up the wrong tree. 
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Stephen Swaffer

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Re: Portable Generator Neutral Bonding
« Reply #8 on: June 29, 2014, 05:53:21 pm »

If the generator is not on the list or is listed as incompatible with the generlink system, then the rules Mike and Frank discussed still apply.  Its  just up to you to figure out if the genny has a bonded neutral or not-owners manual/manufacturers web site and/or an actual ohmmeter test before anything is connected.

Mike may know better, but using a genny and shore power is really not any different than using multiple non-paralleled gennys.   Safety wise you should be OK, but all grounds should be bonded creating one grounded "grid".  Neutrals should stay separate.  I would avoid interconnecting anything from different systems-too much chance for noise/hum to get into the system.  I would probably look at this as an "advanced" application and consider that you need to be confident in your understanding of grounding/bonding to oversee a setup like that-and if I were in charge of it I would likely do some extra metering just so that I knew for sure things were running as expected.
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Mike Sokol

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Re: Portable Generator Neutral Bonding
« Reply #9 on: June 29, 2014, 06:38:58 pm »

Down here in Australia floated neutral generators are designed/approved to power a single load only.  Of course, that's not what occurs in the real world.  People add power strips and run cables everywhere.

But with a single load only there are safety arguments for keeping the floated neutral.

Correct, and that's one of the reasons that these small generators have floated neutrals to begin with. But as you noted, that's not what happens in the real world where power is distributed to various racks, amps, and FOH mixers. That's why I think it's much safer (and code compliant) to neutral-bond these generators and properly earth ground them.
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Mike Sokol
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Re: Portable Generator Neutral Bonding
« Reply #9 on: June 29, 2014, 06:38:58 pm »


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