major lighting problems

[ship]

Ship knowing? Wolf would know more than I about what venu's use now, Ron if he is still out there would know more than any of us I expect.

I don’t do shows anymore.
Of the gear I use or have used, no sub-panel or switch has ever had a seperate ground from the system persay, (grounding rod at the sub-panel) it's all been home run to the main and frequently a actual grounding conductor instead of or in addition to the mechanical ground on this home run for any gear that I care about. Different disconnects are just sub panels, they still have to share a equipment bond with the main panel. A ground wire for general equipment and an Iso ground for the sound gear is not a bad thing to do but probably not needed along with the necessity of a grounding rod at the sub panel/disconnect.

From my understanding of a true ISO ground, given a sub panel powering up an area, the Iso ground equipment is a grounding wire run which bypasses the sub-panel and goes directly to the Main. It must travel directly thru the same conduit as the conductors also - cannot be seperated from them. You should only do this type of run when specifically for gear requiring or benefiting from this home run of the isolated grounding electrode. Reason being voltage drop in resistance unless adiquately sized for maximum overload amongst other code type details. I have never done this and would not recommend doing this without a electrician approving of it. For most instances, running a grounding wire to the sub panel is adiquate.


Bridging Disconnects??? Can be a normal thing to do, can be very dangerous, depends upon what the term is used to describe.


I do know that with each monitor kit we send out there is a UPS, there is also normally a back up light board and just about always above that a back up system that will automatically switch between boards if not run selected saved cues all by itself on it's own battery. This is for some very high profile and higher budget shows however. In a theater there are other automatic switching systems and emergency gear rules which might or might not be configured to run the sound and a limited amount of the lighting system in the case of an emergency power outage. In this way the PA system is part of the show's sound system and it's operator gets the people out. Same with selective lighting circuits in some places.

At one theater I was at using a Strand III for the primary board and a Q-File for the backup board, the Strand was on the main power to the FOH, the Q-File was on the emergency lighting power, the stage was on it's own power. Three seperate transformers feeding the old school house and building. Three phase Delta, Wye and three wire single phase. They also did some connecting of the exit lighting in some areas not covered by that emergency circuit by way of a tap before the main breaker on the school's lighting circuit so I'm not attesting to this place getting a gold star given equipment installed before the main. Could be done and safe as long as it had it's own overcurrent protection but probably not.


I don't do shows anymore just fix stuff however. I do know that if you are having a lot of resistance to ground adding extra grounding rods especially in the area will partially solve this problem and is infrequently done for some shows when there is a long span between source and load, but the neutral still needs to go to the main panel and should not attach at a sub panel even if it has it's own ground for the home run. The sub panel's ground still also has to make that home run also. This grounding rod is only used to help not work on it's own.

I also know that a dedicated grounding conductor (not ISO ground above) as opposed to a mechanical ground (the conduit itself) is superior in conducting electrical current and in protecting against interference. Also that sound equipment should have a home run to the source of power at least sub panel if not it's own sub panel without tapping off the lighting power. Between a ground wire to the sub panel, dedicated neutral in one per circuit used for branch circuits sound is run off of, (sharing neutrals in general is a bad thing on house branch circuits) the sound gear is fairly safe and probably does not need a real ISO ground. For multi-phase gear and loading, a balanced load and properly sized neutral if not two of them in parallel is useful for the lighting.

By the way, grounding takes up a heafty section of the NEC. Lots of do's and don't's and I'm not an expert on all the details of it.


EC&M this month had some info about grounding see if you can follow along. Most of it is about the transformer and service drop/main however and outside the discussion: (Second to last paragraph is the most important to this discussion.)
Applications Corner
Code Basics
By Mike Holt
The NEC requires you to ground (earth) system windings to limit the voltage imposed on the system from lightning, unintentional contact with higher-voltage lines, or line surges. When lightning occurs, high voltages drive high current (as much as 40,000A) into the earth for a fraction of a second. Typically, lightning strikes to wiring are directed to outside utility wiring systems. Therefore, grounding (earthing) the system windings will assist the flow of lightning into the earth.
When a ground fault over 600V occurs, the voltage on the other phases can rise significantly for the duration of the fault (typically three to 12 cycles). This voltage surge during the utility ground fault will be transformed into an elevated surge voltage on the secondary -- possibly destroying electrical and electronic equipment. The lower the resistance of the utility grounding (earthing) system, the lower the secondary voltage surge.

Another function of this earthing is to "stabilize the voltage to earth during normal operation" by providing a common reference point. Thus, the NEC also requires you to ground (earth) metal parts of electrical equipment in or on a building or structure. See 250.24(A) for services and 250.32(A) for separate buildings or structures. You accomplish this grounding (earthing) by electrically connecting the building or structure disconnecting means (225.31 or 230.70) -- with a grounding (earthing) electrode conductor [250.64(A)] -- to a grounding (earthing) electrode [250.52, 250.24(A) and 250.32(A)].

However, grounding (earthing) the metal parts of electrical equipment doesn't protect this equipment from lightning-induced voltage transients or those generated by other equipment in the structure. To provide protection from voltage surges, you must engineer a proper surge protection system.

 

[Radman]

Just curious, has the NEC changed very much since 2002? I haven't gotten the new one, and am curious if I should bother.

 

[ship]

For electricians' beyond the EC&M I stay informed with to the best of my ability with, there are books on the NEC with titles similar to the 2005 changes to the NEC that are available to you to only note changes with. EC&M frequently will run a selected change list to proposed or new differences in the code given it's not much theater based. Given your understanding is similar to or less than mine, I would wait and save up money for the new 2005 NEC Handbook which is a large chunk of change to buy but is ever so worth it in explaining it all beyond dry sleepy words, boring and constantly repeated legalized exceptions of the normal NEC such as in the rules for grounding has. Still yet to get all of the way thru it.

Hmm, what changes might be so earth shattering that could be important to know about???? Perhaps the NEC 1999 ruling that all portable distribution equipment (which would include all AC distro racks and dimmer packs) requiring GFCI protection without a grandfather clause. Imagine every theater or gear owner in the country having to buy some very expensive GFCI either sensing gear by way of a clamp around the wires monotoring the current or individual outlets and even more expensive circuit breakers that are in-compatable with your dimmer pack. Such rules get changed every three years some for the better, some for the worse. Luckily for us, someone re-ruled upon this safety measure in that it would cause problems with power strips and computers plugged into the equipment and not all applications are out of doors and needing a GFCI protection. Such protection is nice and when ever possible one should install a GFCI outlet to save their life, but not reasonable for general entertainment lighting.

That said, I still started pricing out the gear required by code. ETC 96way dimmer down to some home line circuit breaker unit mounted on a sheet of plywood. Heck, I have trouble enough with 18 circuit AC distro units that have no main circuit breaker kill switches as designed by the place I work for's other ME. Hmm, something in the NEC about a maximum of six circuits or a main breaker in making these distro units non-compliant with the NEC. We have them in some form of AC distro for small show in being either compliant with some earlier 1980's code or as designed by someone that had never read the NEC. What ever the case, they are non-compliant as a 18 individual circuit breaker distribution of power unit to shut the darned thing off unit, and still in use. All it's going to take is one electrical inspector to say Boo hoo to this piece of crap and we have to spend a huge amount of money in either paying off the inspector (that's never done) or in shipping out a code compliant distro unit.

Heck when I got to the place I work, I raised the question of circuit breakers. Here we have one circuit breaker per circuit, but in the case of a set of 12 that feeds a Soco 208v circuit and or twelve 120v individual circuits fed off the same circuits, one here will have never have heard of back feeding thru the hot of the breaker that did not trip. In other words, they chose breakers on a 120v circuit not tripping verses the safety of a two breakers worth of 208v circuit having one circuit tripping but the other still live. Took an act of NEC and our own supplier in the more major packs standing up for NEC standards to realize that ... perhaps centralizing instead of bridging to kill certain linked circuit breakers might be better to do, those vendor engeneers in electrical code made us comply finally. Granted that is it's own little war in 400a three phase distro units blowing up during shows due to their own engineer faults in design. In any case, the NEC is both run for us by us and constantly changing for the better of us. If at some point you are offered a position on the panel, fight the place you work for the chanlenge as it will be in intimidating you to really know what you are doing given the omnius position. I was offered and recognized further study on my part, but did not follow thru as opposed to others that represent us tech people you will see on Stagecraft advertising their position I instantly respect. This is all beyone IATSE or any TD position, if you get on the board, try your best to become a seated member. I expect I won't get another chance.



I have a copy of NEC 2002 handbook. It in the sections I most use appropriate to my job probably from memorizing it, I only need to buy the 2005 changes book next year in theory. The idea is that you don't need to buy the next book every year, once you understand the body and more important spirit of the text, only the upgrade book every year that is once you understand the changes to the current rules as most important. Up until you know the past rules that are for the most part safe to listen to, you might as well buy all guides to, changes, handbooks and rules you can get and study it all. It's going to bore you but get thru it because at least some of it will be remembered.

Very boring text but one that if you memorize or at least get a good feel for will pave the way to a career for you in where you work in being safe and you being a real tech person as opposed to just someone that has the ability to focus a light and push a road box. Hmm, what does the quote from the NEC "a plug is not a interconnection device" mean for you as a constant debate about twofers amongst those that "know what they are doing" in being professional verses hack tech people.

Today I was asked by my boss to form up the parts list and quote for fabricating 73 lighting fixtures of my own design to be constructed by the shop (me) and our local welder company in being compliant over shopping at Thomas Engineering (the main company for such audience blinder type fixtues) for the same equipment but stuff that would not be as rugged as necessary for say a perspective (Very high profile rock tour my company is looking to get the next contract for) tour. Knowing the NEC was my base in how to safely and compliantly wire the things. Beyond that improving upon the Thomas design much less our own past designs for lighting fixtures was all up to me. This type of design of lighting fixture knowledge comes from experience in repairing the other fixtures on the market and a certain amount of practice in stage design beyond drafting ability in sending a specification for what to weld off to the welder, it comes from what is learned in college in not only understanting the script, but what will work by way of fixture given the downfalls of past designed fixtures. In any case, It's something like 41 four light fixtures and 32 three light fixtures I'm designing down to the price of crimp to as my own career in bidding the job for me to do as opposed to someone else to do. Something like 264 lamps at about $24.00 each as a final count that even Grainger is in the bidding for supplying - another part of the process of what is going to make a fixture up to your code compliant standards but most cheap as to individual parts making it up code compliant standards.

I'm yet to see the changes to 2005 changes to the 2002 code thus don't yet know what changes there is. I'm fairly informed with the 2002 code, but in the end, the last NEC I tried to read and did not finish, was the NEC 1996. At one point, I was invited to sit on the NEC panel for NEC 2005 along with some very respected sources on the subject I do not feel myself on the level of but somehow I was thought to be of.
Ron the occasional visitor to this website in being a real llicenced in the past electrician would be more qualified than I in understanding all the little details of phase dynamics and power loading on Wye circuits etc, but the NEC board seperates it's panels into various sections and at least for theater lighting I might have a useful voice on thus comfound all of you about in complying with. Believe it or not, it's not some arbitrary board of old timer electricians or fire marshals writing the rules for how we in the theater wire stuff, (that's the Chicago local code where the Union makes more money by running more conduit per circuit, in the theater realated panels, its Us - in the industry that writes our own rules and any of us can some day be a member of the panel that both writes new rules and confirms older requirements of.

In any case, I both was not able to pay for membership by way of red tape at work, and with my own time or personal knowledge in being able to do this thing I feel strongly about but not sufficient in knowledge to. I know what I know but enforcing it on all of you is a different question. In any case, given the above GFCI issue between 1999 and 2002, someting that would cost the industry millions of dollars to comply - and frankly I started to bid out for compliance of but could not even get vendors to bid the gear necessary to comply with, the industry and company I work for snubbed their nose with this rule.

In changes, you can see how important first educating oneself in a period's set or rules is, than staying informed of the changes of is. Some changes are so minor that they are under your necessity in remembering year to year as just a change of words in politically stressing the importance of or they can - those rules be so important that lack of compliance of with can mean a huge hig ticket show is closed down and it will make at least the local news in assuring your company will never do the show again. Theater tech people are a dime a dozen, it's those that stay informed with and educate one self with the overall code that have the advantage and safety to advance in a technical career once the tech part of one's career in lighting diverses from the design part. At some point you are either going to become a designer or senior lighing tech. Both will make a adiquate living but as opposed to studying the MAXXYZ, much less HOG II, I study how to power up the system safely and according to code. Want a quad box on the end of a cable, what is required by code in the minimum to be compliant in this type of thing?

In any case, the NEC has become a theater thing to not only be a goal to comply with, but something run by us own tech people in areas we most must comply with out of safety. Someone saying the NEC just does not understand does not understand themselves. The changes to is something brought up by our own people thus there is no excuse for compliance as time goes on. Sorry but you can't avoid changes, they are either earth shattering to your world or minor detail, but still such details are brought up by fellow electricians if not tech people and are well advised to consider.