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outdoor lights outside

Discussion in 'Question of the Day' started by ship, Sep 28, 2007.

  1. ship

    ship Senior Team Emeritus Premium Member

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    Got a call or two and three and more while taking a nap after work yesterday. I was dog tired in already working long hours this week and even on Monday staying up until 3:30AM in wiring up some upgraded lamp stringers.

    So I answered them in kind as they called after normal working hours as normal. Yesterday later that night also I got a call from a tour later that night that said their Big Light lamps were going bad in a big way and they needed four more by the next morning half a continent away on the East coast. Called about to the West Coast to find some lamps available to ship without results, instead I had to drive to the airport and put some lamps on a plane.

    None the less there was another install that captures the mind and interest with two separate questions I fielded while trying to sleep. Forgot what the other caller that night was asking about...

    First call was about the performance of a standard building’s circuit breaker by the as it were ME of the install. If I have 21 amps load will the circuit breaker blow right away or later? This in him observing the circuit breaker blowing given a after insall calculated load on it.

    So what’s the answer to this question?

    Second question like an hour later was about why the re-distribuited loading on the breaker had some of the Altman CDM arc-source PAR lamps going off at random? This by the production manager as opposed to the ME for the show - both new to such things.

    I know the operation they were doing, even made some oak 3/4"x12" stakes with tapped rear for 1/2-13 bolts for them to fit into overly long screws sticking out of the fixture floor bases. Really cool these stakes at the bottom of 12" floor bases that just kind of threaded on. Earlier in the day I bought them some Edison outlet covers that are plastic covers for an open Edison outlet so as to ease in taping up the cube tapped extension/fixture cords going into three ways for an outdoor application. Intent for the show was to just run out a bunch of 150w CDM PAR fixtures by way of using 15' jumpers between fixtures, cube taps to link them together and plug them in with outdoor timers to the house outlets.

    That concept got modified when they as per earlier did the math in how many amps they were drawing but still was sufficient to at times plug as I’m told in a 150' run of cable end to end, nine fixtures in this way of cable to the first, cube tap and 15' jumper to the next fixture.

    Asked her to meter out the voltage to the last fixture in this line of lights connected by cube taps. She read 94 volts.

    What’s the cause of this? What was the corrective action to this problem I recommended and why would the arc lamps not react well to this voltage in a going on and off type of way? Also, would this noted thing be to all fixtures or just the ending fixtures in the chain of lights?


    So two main questions:
    First: What’s the effects of 21 amps on a 20 Amp building breaker?
    Second: 94 volts... why does it make the lights go blinkie by way of arc source lamps under that voltage, what corrective actions to take and what is the cause?

    This amongst other curious things about such phone calls during my nap raised.

    Plus bonus questions, if you have a T-shaped cube tap as opposed to a cube of one, a cube tap where when tapping connectors to it so as to keep out the water it will be effective, do you need to put such things inside plastic? Other than putting this tapped connection inside plastic, what other things might be an idea to do for any connection points out in the weather? There is one thing specifically I’m looking for.

    Next was the question of if outdoor outlet with flip up cover, do I need to cover the outlet in plastic or is the flip up cover within the NEC recommendations for such a use and safe?

    Finally, given cables with plugs installed on them primarily as opposed to molded plug cables, is it safe to other than cover them given water can get in thru the rear of the plug - or is it safe and is as per a hint to the above there a NEC rule about how to do this, what to do and what’s necessary?
     
    Last edited: Oct 3, 2007
  2. Radman

    Radman Well-Known Member

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    21 amps might be so little over the rating that it may still work for a while, then trip on a slight surge, but thats just an educated guess.

    And my educated guess for the arc lamps is that the ballast might be able to work with the lower voltage to still strike the lamp, but over time the arc could die because it isn't getting quite enough power to sustain itself.
     
  3. Stoldal

    Stoldal Active Member

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    The 21 amps on 20amp breaker would make the breaker trip, that is the experances that i have and normal in use square D breakers. I know that some breaker have a short trip or long trip, i know that all breakers, or almost all have some type of short trip for power spikes. And then the long trips are meant for longer power spikes. The bottom line is am pretty sure that the breaker will trip.

    Plz correct me if i am if anything is wrong
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    question I was asked that night was would it be right away or after a while if at all?
     
  5. Jervas

    Jervas Member

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    Q 1. Trip right away? Probably not - takes a while for any lamp to reach it's full draw if running through a conventional rig. Snap them up quickly and they will trip, surge and they will trip if they are on an older breaker system. If your gear is newer and your behaving yourself (not running the things at full power and snapping them on and off) then you should be OK.
    But why overload a circuit anyway? Poor lighting design if you ask me!
    Q2 - The reason why it's only 94 volts at the end and they are blinking? - the run is too long. Quick solotion - get another power source and halve your run length. Longer solution (if you have time) - rewire them to parallel rather than running them in series. But once again - poor lighting design. Not a bad idea put poor execution.
     
  6. ship

    ship Senior Team Emeritus Premium Member

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    Agreed - poor lighting design but that's given derating and voltage drop due to the amount of cube taps and or connections one can stack up into one circuit is not really much known or thought of.

    In this case, I had the tech person split the chain of lighting fixtures tapped off of in half and run an extension cord about midway to feed the second set of them.

    Solved the problem.

    Wiring in series... not sure that will have fixed the problem explain please given these arc source lamps need at least 96 to 106v minimum to operate. I will have thought wiring them in series will have for 15 fixtures resulted in a lot (signifigant) less voltage per fixture between the voltage drop and now series wiring.
     
  7. Jervas

    Jervas Member

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    Sorry Ship -miss read. Didn't register the arc lamps bit. Your right - probably would result in extra loss. Looks like you weren't the only one who was half asleep when problem solving. ;-)

    I had some goose once ask me why his light tunnel rigged for audience entrance to an outdoor performance area (Made up of the longest single string of bud light you have ever seen by the way) wasn't very effective when he was running it ALL off one transformer!

    Some promoters really should open their wallets and pay the dollars to get the job done right
     
  8. Jervas

    Jervas Member

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    Not sure what the NEC regs are where you are but here in South Australia, to the best of my knowledge the cover is all that is needed. In saying that however I would make double sure that the outlet isn't anywhere were it could get wet. (Like on a building exterior not inside a power kiosk) I rekon - go with caution and plastic it up to be safe.
     
  9. Jervas

    Jervas Member

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    Short answer - NO!
    Once again not sure re NEC rules but here in SA there is not way in heck i'd leave ANY pluged cables outside without total plastic encasement MINIMUM! Our regs say that we have to encase the join point in a plastic lock together cover (sort of like a fat sausage - sorry forgot the correct name just now)
    Even with just these things moisure gets in. Dew, light frosts anything like that can get in there. Sometimes the **** things look dry and they still trip breakers because there is condensation on the pins themselves!
    The rule of the day outside is - PUT IT TOGETHER TOTALLY DRY, WRAP IN IN PLASTIC USING A SUITABLE TAPE AND THEN LOCK A PROTECTIVE PLASTIC CASE OVER IT!
    This is of course a monumental pain in the 'you know what' when you have to de-rig and store every night. But then again, it's better then loosing lights during the show and pissing off 500 audience members, cast, diectors and producers etc.
     
  10. Jervas

    Jervas Member

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    Jeez I keep forgetting you guys only run 110V not 240V
     
  11. ship

    ship Senior Team Emeritus Premium Member

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    Admiration about your post and sub post thoughts. You will find ours is not much more different than ours in many ways. Than is the time I had just gotten out of the military, was doing my first semi-pro design and got hooked into the lighting for it. Some wee design enhansers I didn't do and don't do these days were involved. Had 27 pinspots using #4515 lamps and we were going to make a rainbow. Only one circuit available to feed them. No problem we will just cube tap (threefer) them together. Went on thinking about amperage etc. and while how many of such taps one can use in a circuit, something about the concept didn't allow me to power up this huge contraption of cube tap plugged into cube tape plugged into mutitudes of them. While voltage drop due to the number of connections in a circuit was not a factor, something about combined amperage on the circuit was.

    Still a long living problem for me has over the years been how many times you can add another jumper to a circuit without resistance. Follow spots won't normally work under 94v on a 120v system. Kabuki selenoids also have voltage drop issues if over 16x of them in a circuit. All kind of factors in the choice to have them divide up their string of lights into a few off one feed and the second feed off a direct feed to them. This as opposed to relying upon a large string of taps feeding all.

    Something to consider in general. While like doing Christmas lights, you could just keep plugging one into another until you get like a 2' long string of plugs, there is resistance by way of this connection to consider.

    That's the main point of this concept I would like to point out.
     
  12. Jervas

    Jervas Member

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    Yep, totally with you on the point you made. I must admit that over the years I have seen some truely crazy things. Some even from so called professionals. And don't get me started on some electricians who approach a theatre rig like they were wiring a house. SHEEESHHH!!!!
    Some of the arguments I have had about breakers, saftey switches and how when and where they should be installed or repaired!! Just unbelivable!
    Then there's the moronic promoter who wanted a 100 meter (328.08 feet) 3 phase run to power six catering tents, using heated displays, cuppuchino machines etc. AND still have enough to rig 30 PAR 64's to light the servery areas!!!
    ALL to run off one power kiosk with 32amps per leg!!!!
    UNBELIEVABLE!
     

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