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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Jonathan Johnson on December 02, 2013, 06:06:38 PM
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Throughout this forum, any time there is a discussion of something that involves safety issues, whether it is rigging, electrical, or something else, there are two or three schools of thought:
- If you're not trained, licensed, bonded, and insured to do that kind of work, hire someone who is.
- If you're smart, you can probably do it yourself.
- And a combination of the above: You should probably hire someone who is properly trained, but if that's not an option here's how to do it yourself.
As for myself, I am not licensed, bonded, or insured to do electrical work. But I have been in the construction industry, exposed to proper electrical installations, it's something I'm deeply interested in, I've learned all I can on my own and when I have a question I seek the answer from reputable sources. I've seen a lot of hack jobs; I've looked back at stuff I've done years ago and shuddered. My primary reason for doing it myself is economics. I have the skills to do it properly; my AHJ allows me to do it myself (limited to my own property); and I enjoy it.
However, I will not do it for hire, and I won't do it on property not owned by me or an immediate family member. I draw the line there for my own liability.
Nevertheless, I know that there are people out there who, for the same reasons I cite for myself, want to do things for themselves. As a community, I believe we have a responsibility to help those people understand what is and is not safe work and installation practices. The information we provide helps them understand:
- Whether they have the capability and confidence to do it themselves or to hire a professional;
- Whether something they have done by a professional is done correctly or not; and
- How to do it correctly if they ultimately do decided to do it themselves.
I think that cautioning people to hire a professional for any work that involves life/safety is wise. However, since this is an international audience, we should recognize that much of the developing world does not have access to true professionals in every field, and in many countries there are no standards, codes, or inspections, and the knowledge to do things correctly is nearly impossible to gain without the Internet.
Therefore, I think we should be willing to give advice on correctly installing and working in fields involving life/safety issues -- with the caution that we are not professionals (unless we are) and that we recommend it be done by trained professionals. If all we say is "hire a professional" they may leave in a huff and do it themselves and we've gained nothing. If we give good advice with appropriate reasons and cautions, we've helped make the world a safer place. If nothing else, it gives people an understanding of what they're asking for when they do engage with a professional.
Of course, we can only cite general principles, accepted norms, and codes; a forum such as this is no place to engage in engineering.
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If I reccomend how to rig something, someone does it, and it fails because I didn't know something key about the space I can be sued. I may be personally liable. This is the reason many people say hire a professional with life safety issues.
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The problem is that in many cases, the necessary knowledge is far greater than can be communicated in a forum post or two. People want a procedure when what is required is understanding. Couple that with the attitude of at least one poster in this section who advertises his willingness to perform shortcuts in the name of "the show must go on", and hopefully you see the reason for the reluctance to give a 3-step plan.
I disagree that it is better to give a little advice such that a person can marginally but incompletely improve a situation. In many cases, they're just exchanging one problem for another, and no one wins.
Some folks need to realize that bringing 30,000 watts of amplifiers to a 50-cap bar is ridiculous. For the folks who really care, having an electrician install a range plug in venues for a few hundred dollars makes the world safer for everybody. There are lots of ways to amortize this cost if necessary.
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Qualified does not always mean competent.
Steve.
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We should not encourage unsafe/illegal behaviour.
I 100% agree with the procedure vs understanding comment. A little information allows people to stick their necks out further.
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Perhaps the middle ground, which I think already happens for the most part, with, for example rigging, is to not just say hire a professional, but say
1. Have your system designer designate a place for the speakers
2. Have your structural engineer determine if and how structure can support that load, if it can't go back to step 1. If it can have structural engineer design a support assembly that meets the needs of the system designer
3. Have your rigger hang speakers in designated location using assembly specified by structural engineer.
4. Point out that hiring a qualified system integrator would be best because they generally come with access to or recommendations for all these resources.
People in countries without these resources? What can I say about general practice that isn't already written in any number of books? Reading the books promotes understanding of the concepts and not just a procedure which is the end goal I would hope anyway. The above explains the steps to take but doesn't say what to do specifically.
I think the truth of the matter (at least for the rural south of the US - and I grew up here so I feel I can say this) is some Bubba's daddy hung their speakers with some chain laying around the farm by their handles, and it ain't falled yet, so it must be ok. It's a deep ignorance. Or the stage that blew over outside of Charlotte earlier this year - none of those people think they did anything wrong. The AHJ, doesn't, the promoter didn't. Their thought is: well that dang weather just came up outa nowhere, y'all just can't plan for weather. Sometimes things just fall. But perhaps I digress.
When people come seeking help, then they know enough to know they don't know, which is a great first step. We should tell them the right way to do things (even if the answer is to hire a qualified professional). To do any less would disrespect them for asking in the first place. If we all have to do some explaining and cajoling to get them to understand, then, that's the price of educating someone and making the world a better place.
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There is another reason to get good advice. If you become knowledgeable about a subject then you can tell if you are hiring a trained professional who knows what they are doing. Many Many Many people have hired trained professionals to specify and install sound systems who did not know what they were doing.
Found this week on another forum with regard to a discussion about hum and ground loops.
"I've done dozens, maybe 100s, of sound installs for churches and clubs.
First thing I do is put every piece of grounded equipment on a two to three wire ground adapter (ground lift)
Does that eliminate the hum? If so, I put each piece of equipment back grounded, one at a time, until the hum comes back.Realistically only ONE component needs to be grounded, the ground will transfer to every other piece through shielded cables."
Note, he has done this before, he is a professional.
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that is most likely how people get electrocuted and severely shocked...total FAIL
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Ever wonder how regulated trades come about?
Zap enough people and only electricians will be allowed to wire up PAs. The audio side too.
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Ever wonder how regulated trades come about?
Zap enough people and only electricians will be allowed to wire up PAs. The audio side too.
Do a gig in Chicago's McCormick Place. The Teamsters will unload your truck. The IATSE stagehands will move and set your gear, but the IBEW electricians run and hook up all wires. ALL wires.
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Do a gig in Chicago's McCormick Place. The Teamsters will unload your truck. The IATSE stagehands will move and set your gear, but the IBEW electricians run and hook up all wires. ALL wires.
I had a friend do a gig there... He didn't play well with others. He ended up at the end of the night with a truck of teamsters, a group of stagehands and row of gear and no forklift driver. Everyone claimed the ramp wasn't their jurisdiction.
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Do a gig in Chicago's McCormick Place. The Teamsters will unload your truck. The IATSE stagehands will move and set your gear, but the IBEW electricians run and hook up all wires. ALL wires.
I used to do trade shows there. In addition the riggers will unpack and setup anything in a crate but you needed carpenters to unpack and setup anything in a cardboard carton. I also remember installing mainframe computer systems in Cook County and not being allowed to pull or connect the interconnect cables. Instead I had to point and tell IBEW electricians how and what to hook up even though I'm an electrical engineer.
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Qualified does not always mean competent.
Steve.
+1 , right on !
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Found this week on another forum with regard to a discussion about hum and ground loops.
"I've done dozens, maybe 100s, of sound installs for churches and clubs. First thing I do is put every piece of grounded equipment on a two to three wire ground adapter (ground lift)
Equipment grounding seems to be one of the most misunderstood aspects of power distribution, not only for the music industry, but also for the RV industry. I've been answering questions on my NoShockZone blog for months about floating neutrals on portable generators because none of the generator manufacturers' help desks will tell an RV owner why their voltage/surge protector is shutting down when run from their inverter generator. Even though code offers an exception for portable generators under 5KW with a floating neutral to not require a GFCI receptacle, that's been extended to the idea that ALL portable generators NEED a floating neutral. But as any of you who have hooked up big show generators know, that neutral and ground needs to be bonded together along with an actual ground rod.
If you think that sound crews take a lot of electrical shortcuts, you should see the crazy dog-bone and extension cord adapters used by RV owners to run a 50-amp/240-volt RV shore power plug from a 15-amp/120-volt receptacle in thier garage. And the RVIA is predicting 100-amp/240-volt RVs in the near future. These RVs are hooked up by many retirees who have ZERO understanding of electrical power or safety, sometimes standing in the rain on wet ground making connections without powering down the circuit breakers, and who will accept getting shocked as something normal. They just don't know how dangerous this can be.
I hope that everyone on this forum understands that any electrical shock is cause for concern, and something as simple as a ground-eliminator adapter on a guitar amp can cause a deadly condition at any time. We really do need to educate licensed electricians and installers about grounding safety for musicians. I hope this forum helps all of us understand the dangers as well as best practices and code requirements.
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I agree with TJ on liability-it is a huge concern for me, but at the same time I want to help people that are really wanting to learn and do things the right way-as well I like to do things myself so I know they are done the right way and often that means asking for help myself. I just wish we could get the lawyers to put the blame for troubles where it belongs-not where they think they can get money. An area electrician was sued recently over the drowning deaths of 2 boys in a pool he had wired-but due to an error the lights did not work (boys drowned during a night swim). He had previously been sued over the non working lights by the owner (a municipality) and settled for failing to complete the contact. Obviously, for him to return and fix the lights would have been trespassing and the city failed to get the lights firxed-so 3 years later an accident beyond his control and he is in court again. Many lessons there-but you can't expect the legal system to always use common sense and place blame appropriately.
Jeff is right-I have known many "qualified" if not competent people (journeymen who can't wire a3 way, etc) as well as many competent though technically not "qualified"people. Part of the issue is that I rarely get asked about qualifications or skill-usually the only concern is price. What many do not consider is that the lowest price is often not the best value-but many just don't care so they keep those that are willing to take short cuts in business. Frankly, if I have a customer that needs to save money, but wants to do it right, often they will get a better price from me than the guy that just wants to be cheap-I really don't care to work for him.
Mike, I'll put local farmers up against your RVers any day! Perhaps that might be an interesting thread! Often my first impulse on a farm is to find the main disconnect and kill the power before touching anything-the amazing thing is that farmers are the only group to get exempted from state inspection rules. On a more serious note, is there really any difference between grounding safety for musicians, farmers, RVers, housewives,laborers, etc? Again it goes back to understanding and doing it right-not just "its cheap and it works-even if I don't hookup that green/bare "extra" wire."
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Mike, I'll put local farmers up against your RVers any day! Perhaps that might be an interesting thread! Often my first impulse on a farm is to find the main disconnect and kill the power before touching anything-the amazing thing is that farmers are the only group to get exempted from state inspection rules. On a more serious note, is there really any difference between grounding safety for musicians, farmers, RVers, housewives,laborers, etc? Again it goes back to understanding and doing it right-not just "its cheap and it works-even if I don't hookup that green/bare "extra" wire."
I would have to agree that farms are probably near the top of the list of dangerous places to be as far as electrical safety is concerned.
Here's a case study of a dairy farmer electrocuted by an electric power washer plugged into a corroded receptacle: http://ecmweb.com/bonding-amp-grounding/case-shocking-power-washer
And here's a very sad story about a pair of 14-year old girls electrocuted on a farm while de-tasseling corn in a field. The irrigation pump had its ground burned away the month before by a lighting strike, and it wasn't fixed. The puddles in the corn field were electrified by the water in hundreds of feet of irrigation pipe. http://wcfcourier.com/news/local/detasseling-electrocution-deaths-raise-questions/article_b6d9016e-b851-11e0-8b75-001cc4c03286.html
Sadly, I have dozens of incidents just like this in my files. And yes, electric shock issues are similar across all industries. That's why I find myself on all kinds of forums discussing electrical safety issues. And here's a final one for you to consider. Diesel pickup trucks often include a block heater for easy cold weather staring. Basically it's a hot-water heater element in the water jacket of the engine block. However, when a pinhole leak develops in the heater element, there's about 1 to 2 amps of current that flows from the line to the water. This trips any GFCI it's plugged into, with the result that the driver often disconnects the GFCI outlet or breaks off the ground pin on the plug and goes without a safety ground. So now you have a pickup truck with 120-volts on it's chassis/body and at least 1 or 2 amps fault current capability. So standing on the wet ground and touching the door handle can be deadly.
This is exactly why I started www.NoShockZone.org as a place to write about electrical safety issues for everyone, and why I agreed to moderate this forum. As a musician I'm most worried about stage shocks. But my industrial electric background makes me worry about all sorts of larger building power installations. And my time doing instrumentation for and measuring missile guidance systems components makes me worry about any appliance plugged into a wall outlet.
Education is the key to safety, and it's great to see so many thoughtful and relevant electrical safety questions on this forum. Keep up the good work...
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I was afraid this thread might turn into a flame war. I didn't mean to be a troll, and I'm glad it didn't.
I stand by answering questions honestly and correctly, with caveats. Hiring an experience, knowledgable professional with liability insurance is always the best policy, but I also recognize that's not always possible. In those situations having the right information is necessary.
Instead I had to point and tell IBEW electricians how and what to hook up even though I'm an electrical engineer.
Reminds me of the time I was troubleshooting a networking issue for one of my customers, who leased space in a hospital. Working with a rep from the hospital's IT department, we traced the connection problem to an incorrectly documented patch panel. (This was during an expansion of the hospital, so some of the network wiring had been rearranged and the documentation not completed.) We located the proper jack in the proper panel, and determined what was necessary to fix the issue.
Because of his position, the fellow from the IT department was not permitted to make changes; such a change would require a requisition be filed, go through the chain of command, and a week later someone might get to fixing it. (And knowing that hospital, something would have gotten messed up in the process and there would be even more extensive troubleshooting and requisitions.) However, because I was an outside contractor, I *could* make the change. So he watched me as I unplugged a patch cable and moved it over three feet to a different patch panel. And everything worked.