Since we were headed OT and somewhat irrelevant to the OPs post, I started a new thread, but I want to comment on Guy's staement.The problem I see is that generators are sold consumer-off-the-shelf (COTS) to end users that have no idea about code or situations where they should or should not be used. I know my Honda EU1000 specifically states not to drive a ground rod and has no mention of whether it is a floating or bonded ground. In ways, it seems that including too much information may be seen as the manufacturer as an additional point of liability. The "plug it in, and if you don't understand that, get an electrician" mindset works for and against them.
"The false positive generated by GFCI test circuits on ungrounded Floating Neutral generators does nothing to eliminate faulty equipment and only creates a false sense of security."
First, it has been discussed in depth on other threads here that just because a generator is built without a bonded neutral/ground does not make it OK to use it like that if code does not allow it for the purpose. The places that an unbonded neutral is allowed are limited-and there are ways to bond the neutral.
Secondly, I understand the argument behind your statement; however, what is the purpose for a GFCI? Simply to prevent electrocuting someone. If I place myself between a hot and a neutral no GFCI will ever trip period. If I place myself between a hot and ground-but there is no path back to the neutral (a VERY iffy proposition) then I will not be harmed -GFCI in circuit or not. However, IF there is enough of a path (inadvertent or intentional) to allow a harmful 5 mA to travel through my body and return to the circuit bypassing the GFCI then a GFCI will in fact protect me with or with out a neutral "bond".
The correct way is to follow code and if you are using a genny to supply audio gear for a gig, make sure you bond the neutral and ground. And make sure that neutrals and grounds are separated in any distros/gear that you use.
The "plug it in, and if you don't understand that, get an electrician" mindset works for and against them.
in los angeles any generator thats built on a set of wheels has to be connected to a ground rod.
And I'm guessing the generator must also have its neutral bonded to this "earth ground". Any requirements for metal stages to be bonded to this same generator "ground"?i bond steel frame of the wood deck trailer to the disto panel ground which is connected to the generator ground. metal steps are bonded to the trailer.
... a friend runs gens for tv/movie shoots , i will ask him what is required for his 18 wheeler gen rig.
Unless something changed very recently, it was my understanding from my West Coast IA brothers that the preferred practice in Los Angeles was to not earth ground generators, but rather completely insulate them from earth as stipulated in this excerpt of the safety guidelines established by the Safety Committee of the Contract Service Administration Trust Fund (CSATF), an industry wide administrative body (governed by the collective bargaining agreement by and between the Producers, The International Alliance of Theatrical Stage Employees ("I.A.T.S.E."), the Moving Picture Technicians Artists and Allied Crafts of the United States, its Territories, and Canada ("M.P.T.A.A.C."); as well as the collective bargaining agreements by and between the Producers and the Basic Crafts Locals (Article 18))..i dont know what the motion picture/la la palooza type events/tv shows do about grounding but when i or anyone else goes to rent a gen on axles we "must" have a gen pernit from the city of los angles. if we dont have a permit we are not allowed to rent a gen. once we have the permit the rental company delivers the gen. an electrical inspector comes before the event to make sure an 8' ground rod is driven next to the gen and a proper size ground wire is attatched. he also makes sure the gen isnt parked ubder a tree as i have ben told happens. if the stage is metal or has metal parts he checks that for grounding wires. after he signs off then and only then can i turn the gen on and power stuff up. the city of los angeles might have different rules for union crews but we are just a band doing our own stuff with my pa. we only play in daylight so no lights are used. i havent ben able to talk to my union friend that runs the big stuff cause he is on a production set working 12hr days right now.
“Generators mounted on trucks or trailers shall be completely insulated from earth by means of rubber tires, rubber mats around metal stairways and rubber mats under any type of lift gate or jacking device. Metal supports for trailers shall be insulated by means of wooden blocks. Safety tow chains shall be secured so as to not touch the ground. If complete insulation is not possible, a grounding electrode system shall be installed per the National Electrical Code, Article 250.52.”
Guy Holt, New England Studio Mechanics/IATSE Local 481 Certified Gaffer
ScreenLight & Grip
[email protected]
I question the wisdom of this preferred method.la isnt hard to ground and driving a ground rod is a piece of cake. the exception are if your not near a dirt patch but we never encountered any problems. when a club didnt have the power we needed we used a gen and i clamped the ground wire to the buildings cold water pipe and the inspector approved it.
First, it would seem to require at least as much effort as providing a good earth ground.
Second, all the careful isolation can be undone with just one careless placement of any metallic tool, stand what have you or even somebody leaning against the trailer . Maybe in a tightly controlled studio lot (though I am not usually that trusting of coworkers when it comes to my safety)-but very iffy in a venue with public access.
Though LA is probably a drier environment than I am used to so perhaps less susceptible to accidental grounds and harder to get a good ground?
....there would have to be a fault WITHIN the generator itself, that creates an unintentional upstream bond between the generator circuitry and the frame.
A very high percentage of motors I replace have developed a short between the windings and the frame-and most motors have a measurable conductance to ground-especially with a little age. I would expect the same of a genny-sooner or maybe a lot later there will be a connection like it or not.
So then the GFI is there... to protect personnel in the event of a failure in the generator.
OK, this doesn't make sense to me. If a generator has a floating neutral (not bonded to ground/frame of genny), then what's the point of a GFI that's factory-installed in the generator?
The correct way is to follow code….
Guy, with all due respect you are missing the point of my OP. The ONLY way someone gets electrocuted is if current flows through their body, period. If it returns to the genny via the neutral, the GFCI will never protect them-bonded neutral or not. IF it finds any other path, the GFCI will trip. How is this not safer?
A spider box plugged into the twistlock would qualify as a separately derived system and require a bonded neutral.
Almost all portable generators with factory installed master GFCIs have bonded neutrals – you are not missing something. It is the EU Series generators with floating neutrals that do not have GFCIs
I would imagine that the movie business sets up often enough in locations that would be difficult to drive a ground rod. Concrete streets? Bridges?
That still leaves a hazard for 240 volt equipment. But there is nothing preventing you from bonding a neutral if the genny is not supplying a system that already has a bond. Perhaps the NEC should address it-or perhaps it is a specialized enough application that warrants special training for those in your field? Skilled labor is expected to know how to handle special situations that they may encounter in their job.
I do not see how you can assume that if a genny is manufactured without a neutral bond, that it is always OK to use it that way?
The only gray area to me is where you draw the line between a premises wiring system and plug and cord connected equipment. A genny powering a hammer drill is obviously cord and plug connected equipment. A full blown concert system with lighting, FOH, amp racks and backline supplies is obviously premises wiring. Personally, I would argue that systems utilized under "plug and cord" connected rules should run off genny receptacles only. perhaps with an extension cord or two-no splitters, spider boxes, etc. Do I have a ruling in this? No-but I think a system with wiring splitting off different directions meets the definition of "premises wiring".
FWIW, I usually see movie generators with a ground wire clamped to the nearest fire hydrant on city locations. I have no idea if that is 'legal' or not, but I would expect it to work as well as a small diametre ground rod.
What has been discussed and advocated here is that bonding is always necessary-you might have to do it yourself, but it must be there before you power up.
What has been discussed and advocated here is that bonding is always necessary-you might have to do it yourself, but it must be there before you power up.
From a manufacturing/code/practical/safety standpoint I really think the best plan for under 15 kW gennys would be to require them to be manufactured with bonded neutrals and GFCI receptacles… Unless somebody can explain how that second bond could create a hazard? … That should allow an off the shelf genny to be used safely and in compliance in almost any situation you can come up with?
Since the Hot and Neutral wires pass through the CT of the ground fault sensor but the Ground wire does not (see illustration above), a master GFCI will sense current imbalance in the 240V single-phase circuit supplying the house panel and trip. In the case of home standby power, bonding the Neutral in the generator will defeat the intent of a master GFCI when the Neutral is bonded in the main service panel. This is why Honda’s EU generators are designed with Floating Neutrals.
Guy Holt, Gaffer
ScreenLight & Grip
[email protected]
in los angeles any generator thats built on a set of wheels has to be connected to a ground rod. even all of our contruction site gens had to have a permit from la building and safety and a ground rod driven at the gen. the electrical inspector would come and inspect before we were allowed to use it. a friend runs gens for tv/movie shoots , i will ask him what is required for his 18 wheeler gen rig.i just talked to my friend about how he ground gens. he said an city inspector always shows up to make sure the gen is grounded. he said he drives a ground rod, finds a cold water pipe and get permission to connect to it, finds a service and gets permission to connect to it, etc. he told me he has seen burned up gens where the neutral was lost and the guy operating the gen didnt ground it. he doesnt know if an inspector had ben to the site or not. he told me he has heard about guys using rubber mats aroumd gens but he doesnt do that because even though it protects you the gen still isnt grounded. heres a foto of him and one of the gens he ran.
i just talked to my friend about how he ground gens. he said an city inspector always shows up to make sure the gen is grounded. he said he drives a ground rod, finds a cold water pipe and get permission to connect to it, finds a service and gets permission to connect to it, etc. he told me he has seen burned up gens where the neutral was lost and the guy operating the gen didnt ground it. he doesnt know if an inspector had ben to the site or not. he told me he has heard about guys using rubber mats aroumd gens but he doesnt do that because even though it protects you the gen still isnt grounded. heres a foto of him and one of the gens he ran.
My God man, what happened to his face?Now you know where Darth Vader gets his power. :P
My God man, what happened to his face?he had a black out ! lol lol lol !
My God man, what happened to his face?
In a witness protection program?So's the truck...
So's the truck...
I guess he's kinda hard to find for a repeat job...
Or protecting the confidentiality of the grip truck company, who probably didn't provide direct consent to have their name/logo used.Of course that's the serious answer... wasn't nearly as much fun, though! :P
Of course that's the serious answer... wasn't nearly as much fun, though! :P
Or protecting the confidentiality of the grip truck company, who probably didn't provide direct consent to have their name/logo used.i told the guy i was gonna post the foto. i posted the unblacked out foto on the web about a year ago. the guy in the foto also posted the foto. i have lots of fotos of gen trucks and guys i took. i blacked out the company name because i dont want to provide free advertising for a company that i will never rent from. i decided to black out his face for the hell of it. i was going to black out his hands but decided not to. i'll have to send him the blacked out foto. he isnt a member of psw and doesnt go on any forums, not even the drum forum. his drum set is...............................BLACK like mine !
It's in Los Angeles and if was on a TV shoot, I'd is all for the Witless Protection Program. ;)witless ! lol !
...and that includes the plumber in the foto "moon" lighting at a food court job.