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Author Topic: Generators and grounding and bonding etc etc etc ..... again....  (Read 1801 times)

Debbie Dunkley

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #10 on: May 28, 2020, 01:53:58 pm »

I have another quick question for you guys regarding generators and power....
Is there a power advantage either way to using either of the available outputs on the generators:
1) The 2 NEMA 20 amp receptacles ...or
2) The 30 amp twist lock receptacle and then splitting 2 ways.
Running amps total 23a.
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Mike Monte

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #11 on: May 28, 2020, 02:13:31 pm »

I have another quick question for you guys regarding generators and power....
Is there a power advantage either way to using either of the available outputs on the generators:
1) The 2 NEMA 20 amp receptacles ...or
2) The 30 amp twist lock receptacle and then splitting 2 ways.
Running amps total 23a.

My eu3000is generator is rated at 23 amps.
There are two circuit breakers: one is labeled 20 and the other is labeled 30.  I assume that they are for their appropriate outlets.

I always go from the 30 amp outlet and split from there to have the extra 3a available.

..this is the way I do it and it works for me...

Your unit may be much the same.
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Debbie Dunkley

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #12 on: May 28, 2020, 02:22:15 pm »

My eu3000is generator is rated at 23 amps.
There are two circuit breakers: one is labeled 20 and the other is labeled 30.  I assume that they are for their appropriate outlets.

I always go from the 30 amp outlet and split from there to have the extra 3a available.

..this is the way I do it and it works for me...

Your unit may be much the same.

I have the pigtail 30amp>nema triple tap so I can use this method. I tend to choose the NEMAs because I have 10AWG 50ft cables which eliminates another connection if I use the pigtail adaptor. I suppose NOT splitting the outs and using the 30amp gives me more flexibility on power draw though.
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Mike Monte

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #13 on: May 29, 2020, 06:36:54 am »

I will be providing sound and generators for a smallish show this coming weekend...[/url]

Congrats on actually getting a show (smallish or otherwise) with all that's going on!

I'm up here "hunkered down" in Massachusetts, a Covid hotspot......no shows (or much anything else social-wise) for the foreseeable future.....:(

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Mike Sokol

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #14 on: May 29, 2020, 07:50:20 am »

I will be providing sound and generators for a smallish show this coming weekend...I hope everyone behaves...

Because of this I went on my usual Googling trip and I have a question.
I will be using a Yamaha Ef3000 (PA) and a Yamaha EF2000 (backline). Both generators have open neutrals.
If I will be grounding my generators (copper rod and together), would there be any benefit to me to use neutral/ground plugs ( like the one Mike Sokol recommends) to bond them to their frames?
bonding plug

I believe that both of the generators you mention are indeed floating neutral, so you can safely bond the neutral to the generator frame/ground by using a bonding plug. I consider this best practice for any stage since it also allows you to confirm all stringers and quad boxes on stage as having a proper ground using a simple 3-light outlet tester. And while there's lots of loopholes about running generators without a grounding rod, for any shows I've done with a trailer generator we were always required by the AHJ to put in a grounding rod and bond it to the generator frame/ground. This is largely to reduce lightning damage in the event of a nearby ground strike, but it also pulls the local ground plane you're creating close to earth potential, which is a good thing.

In addition, I always bond any metal stage and steps to the generator grounding point. This is really the only way to make a stage totally safe from shock. Without that bonding its possible to have different voltages on the chassis of the backline amplifiers as well as microphone and the metal railing/steps on the stage. I had that once and it measured 90 volts AC, which would have been quite shocking for the musicians and a contract breaker.   

However, the main questions is what do you really need to do for a few small inverter generators? I would say at the very least (just to protect your equipment and prevent ground loop hum) you will want to bond the two generator grounds together. And bonding the generator ground to the metal stage does help reduce 60-Hz hum from guitars and such since it provides a local ground plane at a common potential.

I consider a lot of this as CYA engineering since you may not really need it unless something goes wrong and an artist gets shocked and hurt. At that point it would be good for you to be able to show that you used best practices for grounding and bonding, mitigating your own blame (and liability). 
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Debbie Dunkley

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #15 on: May 29, 2020, 10:23:28 am »

I believe that both of the generators you mention are indeed floating neutral, so you can safely bond the neutral to the generator frame/ground by using a bonding plug. I consider this best practice for any stage since it also allows you to confirm all stringers and quad boxes on stage as having a proper ground using a simple 3-light outlet tester. And while there's lots of loopholes about running generators without a grounding rod, for any shows I've done with a trailer generator we were always required by the AHJ to put in a grounding rod and bond it to the generator frame/ground. This is largely to reduce lightning damage in the event of a nearby ground strike, but it also pulls the local ground plane you're creating close to earth potential, which is a good thing.

In addition, I always bond any metal stage and steps to the generator grounding point. This is really the only way to make a stage totally safe from shock. Without that bonding its possible to have different voltages on the chassis of the backline amplifiers as well as microphone and the metal railing/steps on the stage. I had that once and it measured 90 volts AC, which would have been quite shocking for the musicians and a contract breaker.   

However, the main questions is what do you really need to do for a few small inverter generators? I would say at the very least (just to protect your equipment and prevent ground loop hum) you will want to bond the two generator grounds together. And bonding the generator ground to the metal stage does help reduce 60-Hz hum from guitars and such since it provides a local ground plane at a common potential.

I consider a lot of this as CYA engineering since you may not really need it unless something goes wrong and an artist gets shocked and hurt. At that point it would be good for you to be able to show that you used best practices for grounding and bonding, mitigating your own blame (and liability).

Thanks Mike.
Yes - CYA is the most important thing.
There will be no metal stage at the show - the band was to play on grass but now due to the forecast they will play in a 3 car garage.
The reason we are using generators is because the owners of the property are renovating and say the shore power is a bit 'iffy'.
I am hoping there will be an obvious place to ground but if not I'll use a rod.
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Jonathan Johnson

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #16 on: May 29, 2020, 11:53:41 am »

Thanks Mike.
Yes - CYA is the most important thing.
There will be no metal stage at the show - the band was to play on grass but now due to the forecast they will play in a 3 car garage.
The reason we are using generators is because the owners of the property are renovating and say the shore power is a bit 'iffy'.
I am hoping there will be an obvious place to ground but if not I'll use a rod.

If you're in a 3-car garage, there's a good chance that's where the building's main electrical panel ("service entrance") is. If so, there's probably a ground rod just outside the wall opposite the panel that you could bond to.

Bonding to the building's electrical system ground is a really good idea as you will bring your system's reference ground potential to the same as that of the building's grounding system. In the event that someone plugs something into a garage outlet (even though they say they won't, don't trust people not to!), not having that bond could create a voltage potential between devices.

Also, if the main panel is there, any chance of getting power tied directly into that, so you don't need the generators?
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Dave Garoutte

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #17 on: May 29, 2020, 01:30:21 pm »

I have the pigtail 30amp>nema triple tap so I can use this method. I tend to choose the NEMAs because I have 10AWG 50ft cables which eliminates another connection if I use the pigtail adaptor. I suppose NOT splitting the outs and using the 30amp gives me more flexibility on power draw though.
I have a heavy gage 30a to 30a extention and plug my pigtail into that.
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Debbie Dunkley

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #18 on: May 29, 2020, 01:49:47 pm »

If you're in a 3-car garage, there's a good chance that's where the building's main electrical panel ("service entrance") is. If so, there's probably a ground rod just outside the wall opposite the panel that you could bond to.

Bonding to the building's electrical system ground is a really good idea as you will bring your system's reference ground potential to the same as that of the building's grounding system. In the event that someone plugs something into a garage outlet (even though they say they won't, don't trust people not to!), not having that bond could create a voltage potential between devices.

Also, if the main panel is there, any chance of getting power tied directly into that, so you don't need the generators?
Maybe - that would be nice and save me a job. However, I am not sure what the 'iffy' part is concerning power at the meter - they didn't elaborate and also I have never had to 'tie-in' to a main panel so not sure what to do there.
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Debbie Dunkley

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Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #19 on: May 29, 2020, 01:52:02 pm »

I have a heavy gage 30a to 30a extention and plug my pigtail into that.

I'm going to use the 30a pigtail that has a triple tap and use the 10AWG extensions into the garage from there. There is a window apparently in the garage and I'm going to see if I can run the cables through that and use some foam to seal the window gap.
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ProSoundWeb Community

Re: Generators and grounding and bonding etc etc etc ..... again....
« Reply #19 on: May 29, 2020, 01:52:02 pm »


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