Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Debbie Dunkley]

Going to be providing sound using a Yamaha EF3000 and a Yamaha Ef2000 inverter generator for the first time in a couple of weeks. I need to go ahead and get what is needed to ground correctly.
I already have the copper wire but I do not have grounding rods or tools to make this easier. I also need to know if it is necessary to ground to the stage and how to do that.
The outdoor shows where I have worked in the past have this all done by the time I get there so I need to learn quickly what my safety requirements are.

[Rob Spence]

Going to be providing sound using a Yamaha EF3000 and a Yamaha Ef2000 inverter generator for the first time in a couple of weeks. I need to go ahead and get what is needed to ground correctly.
I already have the copper wire but I do not have grounding rods or tools to make this easier. I also need to know if it is necessary to ground to the stage and how to do that.
The outdoor shows where I have worked in the past have this all done by the time I get there so I need to learn quickly what my safety requirements are.

If you don't ground the stage (assuming it is metal), there is no fault path from the stage to the generator. My opinion is that it is more important to connect the stage to the generator ground than having ground rods (assuming no severe weather is gonna happen). Of course, ground rods are good and may be required by the AHJ.

I bought some big grip clamps (not brand name Vice Grip) and drilled a 1/4" hole in the frame, then installed a brass bolt & nut. Next, added brass washers and a brass wing nut. I have a #6 green wire with lugs on the ends. One lug goes to my distro (perhaps your generator) and the other to the clamp which attaches to the stage.




Sent from my iPad using Tapatalk HD

[Stephen Swaffer]

In the electrician world there are 2 different terms for what you are asking-grounding and bonding.  Keeping these concepts separate, IMO, makes getting it right easier.

Bonding is connecting anything that "may become energized" with a "metallic path"- in other words copper wire.  By this definition, yes the stage should be bonded.  The main purpose for this is to make sure that if something that shouldn't be energized comes in contact with a live conductor, a breaker will trip before electrocuting someone.

Grounding is the actual electrical connection to earth.  Ground rods for electrical purposes are 8' long and either 1/2" or 5/8" in diameter-the 5/8" are easier to install as they are stiffer.  There are special "ground rod" clamps that connect the wire to them-both can be purchased at either supply houses or the big box stores.  Either a fence post driver, or a hammer drill work well to install them.  Depending on the soil a little water works as well-get the hole started and work the rod and keep adding a little more water, often this is actually less work that driving it in with a post driver-but I always keep one handy in case I need it to finish the job.  Keep in mind "One Call" locate requirements-you do not want to drive one into an underground utility.

Driving a ground rod at the stage and another at FOH without an intentional metallic bonding connection does not provide a safe setup-which is why I said keeping the bonding and grounding concepts separate.

[Ed Hall]

In the electrician world there are 2 different terms for what you are asking-grounding and bonding.  Keeping these concepts separate, IMO, makes getting it right easier.

...

Driving a ground rod at the stage and another at FOH without an intentional metallic bonding connection does not provide a safe setup-which is why I said keeping the bonding and grounding concepts separate.

When using 2 generators, that are not paralleled, like two similar Honda inverters with the parallel kit, should the two be bonded together at the grounding lug of each generator?

My thinking is with one generator for the sound system and the other for backline and FOH you could have different potentials on the EGC if they're not bonded.

[Debbie Dunkley]

When using 2 generators, that are not paralleled, like two similar Honda inverters with the parallel kit, should the two be bonded together at the grounding lug of each generator?

My thinking is with one generator for the sound system and the other for backline and FOH you could have different potentials on the EGC if they're not bonded.

Yes - definitely bonding the 2 gennys together.

Apparently the 'stage' area is not a stage at all but concrete. So .... tie gennies together and take one of the grounds to a rod... or no rod if weather permits?

[Stephen Swaffer]

If there is rebar or structural steel embedded in the concrete, that is potentially a better ground than a ground rod.

I agree with Rob that bonding the stage (and everything using power or in danger of becoming energized through a cut cord or ) is more important than ground rods.  Ground rods (or a grounding electrode like rebar in the stage) are still technically required in this situation-but I'm not gonna inspect your setup .

[Jonathan Johnson]

Yes - definitely bonding the 2 gennys together.

Apparently the 'stage' area is not a stage at all but concrete. So .... tie gennies together and take one of the grounds to a rod... or no rod if weather permits?

In my mind, the best method is a "star ground" (or, more properly, a "star bond") method where each protected system (structural metal of the stage, each individual genny, each ground rod) has a dedicated bonding wire coming to a single, common bonding point (the center of the star). This helps reduce loss of protection should one of those bonding wires become disconnected. You shouldn't depend on the frame of anything to provide a bonding/grounding path -- that would be considered an incidental rather than an intentional bond.

If you bond the stage to genny 1, then genny 1 to genny 2, then genny 2 to the ground rod, a break in the connection between gennys 1 & 2 (or between 2 & ground rod) could cause a loss of safe operation for every protected system.

I guess you could think of the two methods as parallel or serial bonding, respectively. Parallel is preferable.

If there is rebar or structural steel embedded in the concrete, that is potentially a better ground than a ground rod.

There may indeed be steel embedded in the concrete, but connecting to that steel may be impossible!

[Scott Holtzman]

Going to be providing sound using a Yamaha EF3000 and a Yamaha Ef2000 inverter generator for the first time in a couple of weeks. I need to go ahead and get what is needed to ground correctly.
I already have the copper wire but I do not have grounding rods or tools to make this easier. I also need to know if it is necessary to ground to the stage and how to do that.
The outdoor shows where I have worked in the past have this all done by the time I get there so I need to learn quickly what my safety requirements are.

I can't drive sectional ground rod into hard ground anymore.  A simple suggestion, get an inexpensive electric hammer.  Take the bit out and use it to drive the rod into the ground.  Makes the task much easier.

[Keith Broughton]

Could someone clearly explain the exact purpose of the ground rod other than lightning protection?
It obvious that if genny chassis and other metal structures are bonded, then there is a path for faults to trip a breaker.
Unlike the power grid, the genny has no reference to earth, right?

[Debbie Dunkley]

I just did some reading and according to an OSHA fact sheet Doc : DSTM 10/2005,  a grounding rod is not necessary for my purposes - if I am reading it right???
 I cannot find a more up to date document than 2005 so not sure if this has been superseded since its publication.

"Grounding Requirements for Portable and Vehicle-mounted Generators Under the following conditions, OSHA directs (29 CFR 1926.404(f)(3)(i)) that the
frame of a portable generator need not be grounded (connected to earth) and that the frame may serve as the ground (in place of the earth):
• The generator supplies only equipment mounted on the generator and/or cord- and plug-connected equipment through receptacles mounted on the generator, § 1926.404(f)(3)(i)(A), and
• The noncurrent-carrying metal parts of equipment (such as the fuel tank, the inter- nal combustion engine, and the generator’s housing) are bonded to the generator frame, and the equipment grounding con- ductor terminals (of the power receptacles that are a part of [mounted on] the genera- tor) are bonded to the generator frame,
§ 1926.404(f)(3)(i)(B).
Thus, rather than connect to a grounding electrode system, such as a driven ground rod, the generator’s frame replaces the grounding electrode."

[ProSoundWeb Community]