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Author Topic: Grounding for a very small event question  (Read 526 times)

Shawn Herring

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Grounding for a very small event question
« on: October 26, 2020, 02:40:44 pm »

Hey!

I'm just getting into doing really small events such as providing music for camping events. I have 2x yamaha dbr12's and a yamaha dxs18 subwoofer. Audio is played from a laptop or phone, no mixing or live instruments. Connected to house power (120v) with a watt meter I really don't pull more than 550 watts according to the meter. I have a cheapo sportsman gen1000i inverter generator that I'm planning on using to run the speakers outdoors.

I have been doggedly going through posts on this forum regarding safety with bonding and grounding, but most of the scenarios I am reading about are for much larger systems and systems with power distro's and metal stages, both of which I will not be using. The generator has a floating neutral. It also only has one outlet which I normally run a heavy gauge outlet splitter on to give me 3 more outlets that I plug everything into. I've read about the neutral ground bonding plug, but I am unsure if I could attach one of those to my splitter and still have functionality. I have a grounding rod and copper wire to attach to the generator but am unsure if that will be safer, as I have read scenarios where that is also dangerous? Very unclear to me. If the generator sits on a rubber mat and is isolated from the ground is a grounding rod needed? The owner's manual calls for a grounding rod but it is somewhat poorly translated.

I'm just trying to get started doing things safely and without damaging my equipment. Any help with this would be greatly appreciated!
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Brian Jojade

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Re: Grounding for a very small event question
« Reply #1 on: October 26, 2020, 04:38:05 pm »

If all components of the generator are bonded to the generator chassis, you should not need a grounding rod unless you are tying the generator into another system with a transfer switch.  You do want to make sure that the outlet is GFCI protected.  That way, if the electricity decides to flow anywhere but back to the generator, it will trip the breaker.

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Brian Jojade

Shawn Herring

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Re: Grounding for a very small event question
« Reply #2 on: October 26, 2020, 05:48:05 pm »

If all components of the generator are bonded to the generator chassis, you should not need a grounding rod unless you are tying the generator into another system with a transfer switch.  You do want to make sure that the outlet is GFCI protected.  That way, if the electricity decides to flow anywhere but back to the generator, it will trip the breaker.

The generator doesn't have a GFCI outlet, so I could get an adapter for that. The generator I believe is floating neutral, so the components are not bonded to the chassis I think. Would adding the GFCI adapter, then a splitter, then a bonding plug adapter be the solution? That seems somewhat unwieldy.
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John Roberts {JR}

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Re: Grounding for a very small event question
« Reply #3 on: October 26, 2020, 10:24:50 pm »

The generator doesn't have a GFCI outlet, so I could get an adapter for that. The generator I believe is floating neutral, so the components are not bonded to the chassis I think. Would adding the GFCI adapter, then a splitter, then a bonding plug adapter be the solution? That seems somewhat unwieldy.
+1 they make inexpensive GFCI outlet strips that can be plugged into dodgy power and protect the humans.

JR
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Brian Jojade

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Re: Grounding for a very small event question
« Reply #4 on: October 26, 2020, 11:31:19 pm »

+1 they make inexpensive GFCI outlet strips that can be plugged into dodgy power and protect the humans.

JR

Unless you use Crown iTech amps.  They trip GFCI breakers...
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Brian Jojade

Shawn Herring

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Re: Grounding for a very small event question
« Reply #5 on: October 27, 2020, 11:26:34 am »

Unless you use Crown iTech amps.  They trip GFCI breakers...
Great! That sounds great. I'll get one of those guys and call it good.
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Stephen Swaffer

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Re: Grounding for a very small event question
« Reply #6 on: October 27, 2020, 12:48:01 pm »

Do not attempt to plug a bonding plug into a GFCI protected outlet/powerstrip.  It won't hurt anything-but it will instantly trip the gfci.

I would expect, even with a floating neutral, that grounding wires are bonded to the chassis.

Perhaps a bigger issue with a GFCI power strip is leakage current-which has been discussed in several threads.  Just 6 mA leakage is required to trip a GFCI and a certain amount of leakage is allowed in each device to meet UL standards-all those add up and can create an issue.

One of the key functions of a ground/neutral bond is to cause a breaker to trip in the event of a fault.  Small genny's using one cord and plug connected load are pretty safe-if a fault occurs in the tool and energizes the frame, there is still no way to complete a path through a person-if a second tool faults on the opposite leg then you can complete a circuit.  Obviously, the more devices the more chances for faults to occur.

One thing that a lot of people just take for granted is cord grounding conductor continuity.  It would be a good idea to check these on a regular basis.  For construction contractors, OSHA recommends every 3-6 months, or in the case of a potentially damaging event. Probably not a bad guideline for sound providers?
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Steve Swaffer

Chris Hindle

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Re: Grounding for a very small event question
« Reply #7 on: October 27, 2020, 02:03:37 pm »


One thing that a lot of people just take for granted is cord grounding conductor continuity.  It would be a good idea to check these on a regular basis.  For construction contractors, OSHA recommends every 3-6 months, or in the case of a potentially damaging event. Probably not a bad guideline for sound providers?
Heavy road cases and not so bright hands can really take a toll on your cabling....
Chris.
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Daniel Levi

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Re: Grounding for a very small event question
« Reply #8 on: October 28, 2020, 06:21:33 am »

One thing that a lot of people just take for granted is cord grounding conductor continuity.  It would be a good idea to check these on a regular basis.  For construction contractors, OSHA recommends every 3-6 months, or in the case of a potentially damaging event. Probably not a bad guideline for sound providers?

One of my jobs at work is testing portable appliances and checking for ground/earth continuity is VERY important, if the metal casing of something becomes live and the ground connection is missing then it WILL NOT trip a breaker or blow a fuse.

Note that if you are measuring with a multimeter be sure to check what's ohm reading is allowed for a given length of cable for the conductor size (mm/AWG)  and be aware that portable appliance testers that do not give an actual readout just pass/fail can sometimes incorrectly fail a long extension, I have that problem sometimes at work and so resort to a multimeter in those cases.
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John Roberts {JR}

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Re: Grounding for a very small event question
« Reply #9 on: October 28, 2020, 09:44:08 am »

One of my jobs at work is testing portable appliances and checking for ground/earth continuity is VERY important, if the metal casing of something becomes live and the ground connection is missing then it WILL NOT trip a breaker or blow a fuse.

Note that if you are measuring with a multimeter be sure to check what's ohm reading is allowed for a given length of cable for the conductor size (mm/AWG)  and be aware that portable appliance testers that do not give an actual readout just pass/fail can sometimes incorrectly fail a long extension, I have that problem sometimes at work and so resort to a multimeter in those cases.
Indeed an open safety ground may not generate a current overload suitable to blow a fuse or breaker, but GFCI/RCL will still trip if they detect several mAs (6 mA) of current not returning safely through neutral wiring. 

JR
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Re: Grounding for a very small event question
« Reply #9 on: October 28, 2020, 09:44:08 am »


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