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[Mike Sokol]

Can I, in good conscience, use the stage now without proper grounding, should I just refuse the job, or stand paralyzed Waiting for the Electrician or Someone Like Him.

Remember, you can always use a NCVT to do a quick spot check of the stage and backline for voltage. Be sure to check the microphones as well. I often do a stage check with a Fluke VoltAlert which only takes a minute or two and really gives me confidence that I've done everything I can to protect the talent and crew from shock. I have found a few "ungrounded" guitar amps which made the VoltAlert beep close to their guitars, and at least one small PA system tested hot which was plugged into a convention center's duplex outlet that turned out to have an open ground. I found that one while doing a No~Shock~Zone seminar as a guest speaker. So as I walked up front to discuss hot skin conditions I pointed a VoltAlert at the little mixer as a joke, and it beeped. I was able to show that all their mics were "hot" as well as the active speakers. This must have embarrassed the promoter enough that they called an electrician in during the night and the duplex ground was fixed by the morning. Too much fun, eh? 

[Mark Cadwallader]

Grounding the stage ends up being kind of a "not my problem" problem.

• It's not the PoCo's problem; their responsibility ends at the meter (or in this case, the temporary power panel they provide).
• It's not the staging provider's problem (they don't do anything electrical).
• It's not the lighting or sound provider's problem (they didn't provide the stage -- and the distros are basically glorified extension cords).
• It's not the promoter's problem (it never is).

But you, now being made aware of the problem, have a social responsibility to ensure that best practices are observed to create an electrically safe environment. For the best liability protection, you don't address the issue yourself (unless you are a licensed electrician); rather, you hire a licensed electrician to do the work and backcharge the promoter. In the future, you include this in contracts and riders.

P.S. -- If there are multiple stage platforms, there should be an electrical bond of some sort between each frame in addition to the bond from the first platform back to the distro/ground rod.  I'd be careful drilling into stage frame members; drilling in the wrong spot could compromise strength. Some kind of clamp would be ideal; the kind of clamp used for grounding to water pipe may be usable -- but you must have a metal-to-metal connection. Paint or other coatings could create a high-resistance or insulating connection.

This is the issue I was trying to raise above, in post #3 (albeit on a subtle basis).  The contact between adjacent metal frames is rather sketchy, from an electrical bond standpoint (in my layman's view).  I could use a lighting clamp to clamp on a tubular frame with an 8 gauge EGC, but what is the need between sections?  Is that (and truss towers) just a lightning protection issue, or an issue for the energized equipment (lights, audio gear)?  Mark C.

[Mike Karseboom]

Without doing to many quotes, yes THANK YOU all for the clarity on how things can be done in as safe a manner as possible.  I have  new goal to begin thinking more proactively about potential problems and how they might be mitigated.  The idea of sweeping the stage gear with a NCVT as a last step sounds like something worth making the time for as well.


Thank you also for broaching the  moral dilemma that is often presented in the real world.  Do you refuse to serve and bring the event to a crashing halt if everything is not to "code" or at least to your liking?  Doing so may ensure no one will get electrocuted on your watch but what will the consequences be for future work?  I know for me at this juncture I would have a hard time putting my foot down unless I could demonstrate a "clear and present danger" like an energized mic or railing.  A potential threat or something not quite optimum would be much easier to sort of gloss over.


I suppose that is why I was hoping to push the stage grounding onto the utility company.  I think I would like to plead ignorance even though I may know better.   Subconsciously I think I am worried that as soon as I do something like ground the stage, or drive in a grounding rod for a generator, that now I am the de facto  "expert" and if anything does go wrong I will be the first in line for the lawsuits.  Much better to act dumb.  Of course I could be the one that gets zapped!


I have to say that every time I bring the feeder cable and distro out and other people plug into it I feel a greatly heightened sense of responsibility.  Perhaps my liability is no different than when I plug an extension cord into a wall outlet and then let the  muso's plug their amps and pedals into my stage stringers.  But the distro seems to take it to a whole new level of "I should know what the hell I am doing". 

[Ray Aberle]

Without doing to many quotes, yes THANK YOU all for the clarity on how things can be done in as safe a manner as possible.  I have  new goal to begin thinking more proactively about potential problems and how they might be mitigated.  The idea of sweeping the stage gear with a NCVT as a last step sounds like something worth making the time for as well.

Thank you also for broaching the  moral dilemma that is often presented in the real world.  Do you refuse to serve and bring the event to a crashing halt if everything is not to "code" or at least to your liking?  Doing so may ensure no one will get electrocuted on your watch but what will the consequences be for future work?  I know for me at this juncture I would have a hard time putting my foot down unless I could demonstrate a "clear and present danger" like an energized mic or railing.  A potential threat or something not quite optimum would be much easier to sort of gloss over.

I suppose that is why I was hoping to push the stage grounding onto the utility company.  I think I would like to plead ignorance even though I may know better.   Subconsciously I think I am worried that as soon as I do something like ground the stage, or drive in a grounding rod for a generator, that now I am the de facto  "expert" and if anything does go wrong I will be the first in line for the lawsuits.  Much better to act dumb.  Of course I could be the one that gets zapped!

I have to say that every time I bring the feeder cable and distro out and other people plug into it I feel a greatly heightened sense of responsibility.  Perhaps my liability is no different than when I plug an extension cord into a wall outlet and then let the  muso's plug their amps and pedals into my stage stringers.  But the distro seems to take it to a whole new level of "I should know what the hell I am doing".

Well, Mike, it is said that with electricity (and rigging, for that matter!), if you have to ask about something, you're not qualified to do it.

On the other hand, it is important to know enough to know when to say "no" to a dangerous situation, so you are doing the right thing here!

(As for liability for electrical mistakes... well, that's what your insurance policy is for...)

Ray

[Jonathan Johnson]

This is the issue I was trying to raise above, in post #3 (albeit on a subtle basis).  The contact between adjacent metal frames is rather sketchy, from an electrical bond standpoint (in my layman's view).  I could use a lighting clamp to clamp on a tubular frame with an 8 gauge EGC, but what is the need between sections?  Is that (and truss towers) just a lightning protection issue, or an issue for the energized equipment (lights, audio gear)?  Mark C.

How often are/were portable metal stages (and other stage structures: truss, etc.) grounded before the topic was brought up in this forum a few weeks ago? Is this a new area of thought -- hence the lack of approved tools and methods?

That is, was the world blissfully unaware of the potential dangers until a few people with too much free time began thinking about the issue?

[Mike Sokol]

That is, was the world blissfully unaware of the potential dangers until a few people with too much free time began thinking about the issue?

IDK... but we were all blissfully unaware of grounding stage amps and PA systems back in the 60's and 70's and all it took were some dead musicians to change our minds. Of course, nowadays all stage amps and PA systems are grounded by the manufacturer which is enforced by the NEC and UL code. Stages, not so much. But code is now changing to include lots more grounding/bonding for things like hot tubs and marinas.

As far as stage grounding, most of the time we're working on inside wooden stages, but every time I work a festival on a portable metal stage and it begins to rain I get a little squeamish around all that electricity. Even though it's more work and responsibility, I feel good about grounding it. And occasionally one of the band's rodies asks me why I'm driving a ground rod, etc...

After I got my BIG shock from a 650-volt power supply back in the late 70's (was knocked unconscious) I began bringing a Ground Loop Impedance Tester (GLIT) to gigs and tested for proper grounding of the wall outlets as well as checking all backline amps for a proper ground plug. So while the other bands in the area complained about getting shocked, guys in my band began to thank me for NOT getting shocked, especially the times we would play on open stages outdoors that were wet.

I personally think it's important to take the high road and try to do the right thing as much as we can. This business is hard enough as it is without having to worry about getting electrocuted.

[David Sturzenbecher]

IDK... but we were all blissfully unaware of grounding stage amps and PA systems back in the 60's and 70's and all it took were some dead musicians to change our minds. Of course, nowadays all stage amps and PA systems are grounded by the manufacturer which is enforced by the NEC and UL code. Stages, not so much. But code is now changing to include lots more grounding/bonding for things like hot tubs and marinas.

As far as stage grounding, most of the time we're working on inside wooden stages, but every time I work a festival on a portable metal stage and it begins to rain I get a little squeamish around all that electricity. Even though it's more work and responsibility, I feel good about grounding it. And occasionally one of the band's rodies asks me why I'm driving a ground rod, etc...

After I got my BIG shock from a 650-volt power supply back in the late 70's (was knocked unconscious) I began bringing a Ground Loop Impedance Tester (GLIT) to gigs and tested for proper grounding of the wall outlets as well as checking all backline amps for a proper ground plug. So while the other bands in the area complained about getting shocked, guys in my band began to thank me for NOT getting shocked, especially the times we would play on open stages outdoors that were wet.

I personally think it's important to take the high road and try to do the right thing as much as we can. This business is hard enough as it is without having to worry about getting electrocuted.

While we are on topic, is anyone grounding their roofs?  Or are we lumping roofs into the term "stage"?

[Mike Sokol]

While we are on topic, is anyone grounding their roofs?  Or are we lumping roofs into the term "stage"?

I have a study somewhere where an electrician who was checking out a lighting fixture on a roof was shocked by an ungrounded roof section which was electrified by a wire with the insulation worn through (I think that was why the lighting fixture was dead). He was startled enough to fall from the ladder he was on and shattered the bones in both of his legs. A big lawsuit was filed but I don't think he was awarded any money since he was "supposed" to take proper precautions and know better. I'll try to dig out the link today.

So yes, metal roofs are supposed to be bonded to building steel (and ground) according to code, as is your furnace and duct work in your house. I'll see if I can find a synopsis of the new 2014 NEC grounding requirements and post them on their own thread.   

[Ron Hebbard]

Yes to bonding the stage to the incoming ground (EGC - Equipment Grounding Conductor)

Yes to bonding the lighting truss to the EGC as well.

The size of the ground/bond wire required is a function of both max circuit breaker capacity and lightning protection. So you should match whatever size ground wire is coming in from the POCO if possible, but probably not smaller than 8 gauge for lightning protection. Also, avoid sharp turns with this bonding wire if possible (no right angle bends) since that will promote lightning side flashes. That's in the amateur radio manual, and those guys worry about lightning a lot. 

Yeah, we don't like to think about lightning, but by definition these shows are outside in the summer and typically the highest structure in a flat field. Even if you evacuate the band and stage crew when lightning rolls in (you do, don't you), your equipment will stand a much better chance of surviving a nearby lightning strike if the stage and lighting trusses are properly bonded to earth.

Mr. Sokol Sir!

While reading this thread as it progresses, car battery booster cables keep crossing my mind.
No they're not purpose designed and approved for bonding metal stage sections together.
No they're not designed to make a fabulous electrical connection through rust and/or paint.
On the plus side;
They're readily available.
They're produced in sufficient quantities to be affordable.
Many clamps, with a little persuassion, could chew through paint and corrosion.
They'd be quick and easy to apply / strike AND without tools.
They're manufactured in a choice of guages, most adequate for bonding metal stage sections together.
They may only be rated for 12 - 24 VDC but perhaps they'd be up to this sort of challenge.

One more negative point;  they'd probably walk like crazy during strikes and load-outs.

Yes, I understand they're not the 'right' answer but they keep crossing my mind as something appreciably better than nothing.

While we're chatting, I'm VERY pleased to see you and your forum here at Prosound.
Thank you so much and your notion of inviting manufacturer's engineers as guests is excellent.
In return for their participation, I don't have a problem with them mining your readers for any knowledge and application info they can glean even though this is leaning towards a violation of forum policy for manufacturers and their reps.  In this sense we're inviting the manufacturers to participate and I think it would be in everyone's interest to provide any feedback requested.

Toodleoo!
Ron Hebbard

[jasonfinnigan]

Mr. Sokol Sir!

While reading this thread as it progresses, car battery booster cables keep crossing my mind.
No they're not purpose designed and approved for bonding metal stage sections together.
No they're not designed to make a fabulous electrical connection through rust and/or paint.
On the plus side;
They're readily available.
They're produced in sufficient quantities to be affordable.
Many clamps, with a little persuassion, could chew through paint and corrosion.
They'd be quick and easy to apply / strike AND without tools.
They're manufactured in a choice of guages, most adequate for bonding metal stage sections together.
They may only be rated for 12 - 24 VDC but perhaps they'd be up to this sort of challenge.

the cables you refer to are offten CCA (Copper-Clad Aluminum) cables which aren't suitable for this purpose. Also for temporary power sitituations where your grounding rod will likely be distant and near a gennie you really want a go insulator to protect it, those cables aren't rated for the voltage or amperage which may make it melt.

CCA is generally only good for high frequency or low power stuff. DC and AC power just aren't the same. also I believe the cables would be less than 20feet.

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