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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: Jeff Bankston on July 25, 2018, 03:11:38 PM
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I see a lot of new 6/4 SOOW rolls for sale thats not UL rated. Is this legal for power distro use in the USA ?
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I see a lot of new 6/4 SOOW rolls for sale thats not UL rated. Is this legal for power distro use in the USA ?
I though I read some time in the past here that raw cable is often not UL approved but that an assembly might be.
Of what use to us is UL cable? As soon as we attach cord caps (even if UL listed), the assembly is not UL approved.
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I see a lot of new 6/4 SOOW rolls for sale thats not UL rated. Is this legal for power distro use in the USA ?
Perhaps a more relevant question is what are you going to do with it? Though 6/4 is commonly used for a 50A connection, it’s technically not rated for that with 3 current carrying conductors, which includes any pro audio application with 120v loads. For code and voltage drop reasons, 4/4 is a better choice.
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Perhaps a more relevant question is what are you going to do with it? Though 6/4 is commonly used for a 50A connection, it’s technically not rated for that with 3 current carrying conductors, which includes any pro audio application with 120v loads. For code and voltage drop reasons, 4/4 is a better choice.
Using 6/4 from a distro to spider boxes. 2 hots 1 neutral 1 ground. 25' and 50' runs. I prefer 4/4 but the wire wont fit in the Hubbell CS8365C and CS6365C lugs without cutting some strands. My old 6/4 cable is so scuffed up and wore out I cant read the writing on it anymore to see if it was UL rated.
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Using 6/4 from a distro to spider boxes. 2 hots 1 neutral 1 ground. 25' and 50' runs. I prefer 4/4 but the wire wont fit in the Hubbell CS8365C and CS6365C lugs without cutting some strands. My old 6/4 cable is so scuffed up and wore out I cant read the writing on it anymore to see if it was UL rated.
4/4 won't fit in a Hubbell Cali connector? Hmmm. How about in another brand? I'm planning on building some cables up this fall.
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4/4 won't fit in a Hubbell Cali connector? Hmmm. How about in another brand? I'm planning on building some cables up this fall.
I already have 12 male and 12 female Hubbells. And at $60.00+ each I am not going to buy anymore. The Hubbells are the best.
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I just tried a #4 battery cable I took off my truck and I can make it fit. Wont be easy doing 4 wires. I might need some longer screws for the rear clamps. I will definitely use 4/4 for he mixing board run. I see both UL and non UL 4/4.
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I just tried a #4 battery cable I took off my truck and I can make it fit. Wont be easy doing 4 wires. I might need some longer screws for the rear clamps. I will definitely use 4/4 for he mixing board run. I see both UL and non UL 4/4.
As far as i know, UL can only be applied to a FINISHED PRODUCT, not the raw cable.
If you saw an extension labelled that way, it was factory build. NOT u-mak-em.
Chris.
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It is my understanding that UL-listed components may be used to build assemblies, but the exclusive use of listed components does not mean that the assembly itself is UL approved (listed).
That said, I'd rather be able to show the AHJ I'm using UL listed parts in my home-made extension cords than otherwise. (Not that I've been questioned on the subject, but I'm a cautious s.o.b.)
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Though 6/4 is commonly used for a 50A connection, it’s technically not rated for that with 3 current carrying conductors, which includes any pro audio application with 120v loads.
Interesting. In a 125/250V, 3 pole, 4 wire, single-phase system, as commonly encountered in audio (connecting a generator to a spider box via a 50A Cali plug), my interpretation of NEC table 400.5(A) allows for 55 A in 6 AWG up to an ambient temperature of 30 deg C. We can use column B as only two of the conductors are "current carrying". The third (neutral) conductor carries only the out-of-balance component. This makes physical sense so long as we are not concerned with harmonic current in the neutral.
For higher ambient temperature they tell us to derate in accordance with Table 310.16, using the column corresponding to the cord's rated temperature (or, I suppose, the lowest temperature rated connection made to that cord). The trouble is that the lowest column in the table 310.16 is for 60 deg C and the closest piece of SOOW I have lying around has 40 deg C stamped on it. What to do now?
640.42(E) (Audio Signal Processing, Amplification, and Reproduction Equipment), refers us to 520.5, 520.10 (Theaters...), and 525.3 (Carnivals...), which mostly just refer us back to Article 640 and say nothing special about ampacity. So it appears that article 400 applies to us. Sorry to flog this dead horse but is this everyone's understanding?
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Interesting. In a 125/250V, 3 pole, 4 wire, single-phase system, as commonly encountered in audio (connecting a generator to a spider box via a 50A Cali plug), my interpretation of NEC table 400.5(A) allows for 55 A in 6 AWG up to an ambient temperature of 30 deg C. We can use column B as only two of the conductors are "current carrying". The third (neutral) conductor carries only the out-of-balance component. This makes physical sense so long as we are not concerned with harmonic current in the neutral.
For higher ambient temperature they tell us to derate in accordance with Table 310.16, using the column corresponding to the cord's rated temperature (or, I suppose, the lowest temperature rated connection made to that cord). The trouble is that the lowest column in the table 310.16 is for 60 deg C and the closest piece of SOOW I have lying around has 40 deg C stamped on it. What to do now?
640.42(E) (Audio Signal Processing, Amplification, and Reproduction Equipment), refers us to 520.5, 520.10 (Theaters...), and 525.3 (Carnivals...), which mostly just refer us back to Article 640 and say nothing special about ampacity. So it appears that article 400 applies to us. Sorry to flog this dead horse but is this everyone's understanding?
I never had an issue before with audio use or on construction sites when I was a commercial electrician(I'm retired now). Construction sites connect a 6/4 cable to a 50 amp 2 pole breaker in on a generator or permanent service panel and daisy chaining many spider boxes together so we can power the temporary lights and power tools. All temp power requires a permit and a LA building and safety inspector comes once and makes sure the temp power cords and boxes in good condition. My question was the non UL listed 6/4. I went to home depot earlier and all the bulk cable has UL stamped on it. I called one of the electrical supply houses and they have bulk cable that is UL listed and non UL listed and thats all they could tell me. There are electrical suppliers on the web and ebay selling name brand 6/4 and 4/4 that is both UL and non UL and the price is roughly the same for either. I will buy the UL listed. I'm going to continue to use 6/4 for my 25' and 50' runs and 4/4 for the run to my FOH mixer. As for current carry yes a hot leg is current carrying and the neutral and ground are not.
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As for current carry yes a hot leg is current carrying and the neutral and ground are not.
This is not correct for non-resistive loads such as lighting dimmers and power amps. The neutral counts as a current-carrying conductor.
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This is not correct for non-resistive loads such as lighting dimmers and power amps. The neutral counts as a current-carrying conductor.
We were never aware of that in the construction industry but we also never had anything to do with PA equipment or stage lights. We also had to wire according to the blue prints and were not allowed to make changes with written permission from the electrical engineer and a written change order. How does that affect house wiring for home stereo systems and my old QSC series 3 power amps ?
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I just got off the fone to the electrical dept at Los Angeles Building and Safety. They want to see UL printed on or molded into the outer jacket of SOOW cable no matter if its bulk with no ends or with user installed ends or with ends from the factory. The guy I talked to was quite "shocked" that there is non UL SOOW being sold.
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This is not correct for non-resistive loads such as lighting dimmers and power amps. The neutral counts as a current-carrying conductor.
Hi TJ, do you have a code reference for that? I have not been able to find it. Thanks. --Frank
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310.15.B.5 (c)
Interestingly, if you are supplied by a 4 wire Y connected 3 phase, the neutral always counts [paragraph (b)], so unless you are using a distro exclusively on a single phase/split phase system, you need to count the neutral.
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310.15.B.5 (c)
Interestingly, if you are supplied by a 4 wire Y connected 3 phase, the neutral always counts [paragraph (b)], so unless you are using a distro exclusively on a single phase/split phase system, you need to count the neutral.
We are talking single phase not 3 phase. hot - hot - neutral - ground = 4 wires. 120V / 120V. 3 phase is hot - hot - hot - neutral - ground = 5 wires. 120V / 120V / 120V.
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310.15.B.5 (c)
Interestingly, if you are supplied by a 4 wire Y connected 3 phase, the neutral always counts [paragraph (b)], so unless you are using a distro exclusively on a single phase/split phase system, you need to count the neutral.
Stephen, does the phrase "being supplied by" refer to the main service connection (to the building) to which the 50A split phase distro is connected via the Cali connector?
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310.15.B.5 (c)
Interestingly, if you are supplied by a 4 wire Y connected 3 phase, the neutral always counts [paragraph (b)], so unless you are using a distro exclusively on a single phase/split phase system, you need to count the neutral.
Yes, I noticed that. 310.15(B)(4) informs us that in the case of (b) two legs and a neutral of a 3-phase wye-connected system or (c) all three legs and the neutral of a 3-phase wye-connected system that supplies non-linear loads, the neutral counts. But it looks like they let us off the hook for single-phase (a).
I think I can design a "load from hell", however, that will burn the neutral in a single-phase system, but it sounds like it hasn't been a problem from NFPA's point of view. Try 884 uF across one leg and 7.95 mH across the other. Each will pull 40 A at 120 V. But the currents will add in-phase in the neutral to give 80 A, a bit much for the 6 AWG wire :) And it's not even a non-linear load, just a linear load with a sucky power factor.
Seriously, I would like to know where we stand on the 6 AWG 50 A single-phase question.
--Frank
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Yes, I noticed that. 310.15(B)(4) informs us that in the case of (b) two legs and a neutral of a 3-phase wye-connected system or (c) all three legs and the neutral of a 3-phase wye-connected system that supplies non-linear loads, the neutral counts. But it looks like they let us off the hook for single-phase (a).
I think I can design a "load from hell", however, that will burn the neutral in a single-phase system, but it sounds like it hasn't been a problem from NFPA's point of view. Try 884 uF across one leg and 7.95 mH across the other. Each will pull 40 A at 120 V. But the currents will add in-phase in the neutral to give 80 A, a bit much for the 6 AWG wire :) And it's not even a non-linear load, just a linear load with a sucky power factor.
Seriously, I would like to know where we stand on the 6 AWG 50 A single-phase question.
--Frank
Answering your question and Jeff's from earlier, for residential wiring, #6 NM wire can handle 55 amps and so is fine for a 50A load. This is due to a much thinner jacket than SOOW cord, so it sheds heat better. It is also fed almost exclusively from a split phase service, so other than Frank's extreme cruddy power factor situation, it's unlikely that the neutral current will be significant, and therefore is not counted as a current-carrying conductor in most cases.
Shifting over to SOOW and live sound reinforcement, the missing link in most folks' minds is that while a Cali-fed spider box is a two-phase device, when used in a commercial building, it's fed from a 3-phase service, even though only 2 phases are used. This significantly increases the neutral current compared to the same load fed from a split-phase residential service.
This is largely academic in real life, however. 6/4 cord is indeed used for 50A cables, and it would take an observant inspector to catch it. That said, I think this is a foolish compromise. Amplifier power is heavily dependent on voltage drop. We spend thousands of dollars on larger amplifiers and dragging more speakers to gigs, only to give up a significant fraction of that power to undersized power distribution. This makes no sense. What's unlikely to cause a fire (the main goal of the NEC which is published by the National Fire Protection Association) isn't what's optimal.
Friends that care about good sound quality don't let friends use 6/4 cord for 50A services.
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Stephen, does the phrase "being supplied by" refer to the main service connection (to the building) to which the 50A split phase distro is connected via the Cali connector?
TJ answered this already-but why should it matter how it is supplied? In a 3 phase service, phases are separated by 120 deg-not 180 deg as they are in a single phase 120/240 service (think back to high school and vector math). It is even possible that a building with a 120/240 volt panel is supplied from a 3 phase transformer-my POCO refers to this as a "networked" system. If I install a single phase service on a networked system, I have to install an additional terminal on the meter base to account for the neutral.
And yes, the NEC is not a design reference-even though that is often how it is used.
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I called the city of LA again about the non UL listed cable and had a friend in another state do some checking. For non commercial use non UL listed does not matter. Non commercial use would be for home use. My landlord has a spider box with 6/4 that he uses for yard work with the electric mower and tree trimmer and weed wacker. His service is 2 pole single phase. A friend runs gennys on semi trailers and told me long ago that he gets better power results from single phase setting. We always ran the temp gennys in the single phase mode on construction sites and I also use the single phase setting to power the PA. I also use one 6/4 cable from the main distro to one spider box for the PA, I dont daisy chain those.
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I called the city of LA again about the non UL listed cable and had a friend in another state do some checking. For non commercial use non UL listed does not matter. Non commercial use would be for home use.
I also use the single phase setting to power the PA.
top line Non Commercial use Ok for home. but when using to power the PA this is commercial use.
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And yes, the NEC is not a design reference-even though that is often how it is used.
Good point. Complying with code is one thing. Complying with physics is (sometimes) another. I will say though that I find NEC an incredibly thorough, consistent, and sensible set of rules, as rules go. -F
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Re: friends don’t let friends use 6-4 on 50a service...
Just because it is a 50amp service doesn’t imply 50a of current draw.
My rig draws around 30a on a bad day. I use 6-4 to reduce the voltage drop.
50a Cali connectors are more common for me than L14-30
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I will buy the UL listed. I'm going to continue to use 6/4 for my 25' and 50' runs and 4/4 for the run to my FOH mixer.
Slightly off-topic, but why on earth are you running 4/4 to FOH? Does your mixer pull 50 amps? Is it 1000' from the stage? Do you have massive lights out there?
I can't think of any other reasons to use 4/4 to FOH.
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We ran 8/5 to FOH back in Ye Olde Analogue Dayz. A PM4000 or Midas H3000 could draw 20 amperes. Steady. And when the kick drum hit the voltage would drop 5-10 volts. We needed all the help we could get.
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We ran 8/5 to FOH back in Ye Olde Analogue Dayz. A PM4000 or Midas H3000 could draw 20 amperes. Steady. And when the kick drum hit the voltage would drop 5-10 volts. We needed all the help we could get.
Ya, these "Digital Kidz" never had the "fun" of doing good old fashioned rock and Roll, arena style. 6 man lift on the board, 3 TONS of AC feeder....... (well, it sure felt like 3 tons). An occasional X-Fmr for the mains, well, just because.
Ahh. the "Good old days". May they rest in pieces. ;D
Chris.
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Ya, these "Digital Kidz" never had the "fun" of doing good old fashioned rock and Roll, arena style. 6 man lift on the board, 3 TONS of AC feeder....... (well, it sure felt like 3 tons). An occasional X-Fmr for the mains, well, just because.
Ahh. the "Good old days". May they rest in pieces. ;D
Chris.
We ran 8/5 to FOH back in Ye Olde Analogue Dayz. A PM4000 or Midas H3000 could draw 20 amperes. Steady. And when the kick drum hit the voltage would drop 5-10 volts. We needed all the help we could get.
In analog console days, for my Series 5/MH4 I had snakes that had 10/4 or 14/4 to FOH, with 180'-200' lengths. At those lengths voltage sag was not a perceptable issue (no lights dimming). I never ran 300'.
None of those, mine nor yours, is 4/4, and Jeff is running that now. AFAIK nobody did it then and since I can't think of a reason to do it now, I'm curious why he feels it's necessary to lug that much copper around.
It is indeed "AC Feeder"; who runs AC Feeder to FOH and why? Unless FOH is vastly more than audio processing.
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Re: friends don’t let friends use 6-4 on 50a service...
Just because it is a 50amp service doesn’t imply 50a of current draw.
Code requires all distribution wiring to be sized to the upstream circuit breaker whether that capacity is used or not. A 1A load from a 50A breaker should be fed by #4 wire (unless you are sure it will never be fed from a 3-phase source where #6 wire is OK per code) as there is the potential for 50A to be drawn in a different circumstance, and small-gauge wire may have too much resistance to trip the breaker if there's a short, but plenty of resistance to create enough heat to start a fire.
My rig draws around 30a on a bad day. I use 6-4 to reduce the voltage drop.
If you're drawing sustained 30A, you are probably spiking a fair bit higher on kick drum hits. It's not easy to measure this - most volt meters have some smoothing which will read lower than what the actual peak draw was.
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SOOW
6/3 - 55A
6/4 - 45A
4/4 - 60A
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Slightly off-topic, but why on earth are you running 4/4 to FOH? Does your mixer pull 50 amps? Is it 1000' from the stage? Do you have massive lights out there?
I can't think of any other reasons to use 4/4 to FOH.
The Midas draws more current than my others boards. I have 3 power supplies. I also added a few other electrical things at FOH. I need a single cable that will reach up to 150' from front of stage and that means at least 160'. Then it has to connect to the main distro so figure 200'. It is single phase and that means 2 hot legs to a 50A breaker(not a 60A). The Midas is on one phase and everything else is on the other phase. With a 120V at the distro the voltage will be 115V at the Midas on its phase with a 200' cable lenght from the distro with 4/4 cable. With 6/4 the voltage will be 112V. 4/4 cable is the way to go. 6/4 50' cable runs on 45A breakers for the amp racks is plenty. I put my amps behind the speakers and that saves on copper and others things.
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The Midas draws more current than my others boards. I have 3 power supplies. I also added a few other electrical things at FOH. I need a single cable that will reach up to 150' from front of stage and that means at least 160'. Then it has to connect to the main distro so figure 200'. It is single phase and that means 2 hot legs to a 50A breaker(not a 60A). The Midas is on one phase and everything else is on the other phase. With a 120V at the distro the voltage will be 115V at the Midas on its phase with a 200' cable lenght from the distro with 4/4 cable. With 6/4 the voltage will be 112V. 4/4 cable is the way to go. 6/4 50' cable runs on 45A breakers for the amp racks is plenty. I put my amps behind the speakers and that saves on copper and others things.
Can you run the Midas on 240V? Half the voltage drop....
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The Midas draws more current than my others boards. I have 3 power supplies. I also added a few other electrical things at FOH. I need a single cable that will reach up to 150' from front of stage and that means at least 160'. Then it has to connect to the main distro so figure 200'. It is single phase and that means 2 hot legs to a 50A breaker(not a 60A). The Midas is on one phase and everything else is on the other phase. With a 120V at the distro the voltage will be 115V at the Midas on its phase with a 200' cable lenght from the distro with 4/4 cable. With 6/4 the voltage will be 112V. 4/4 cable is the way to go. 6/4 50' cable runs on 45A breakers for the amp racks is plenty. I put my amps behind the speakers and that saves on copper and others things.
Thanks for that explanation. Just out of curiosity nosiness, how much power does the Midas draw? And do you have all 3 power supplies on at the same time?
Note Tim's response. Relevant to it, by using 240v you also get the benefits of running on balanced power, which many people spend $$$ to get from 120v. Using 240v you get them for free.
Sounds like you have a pretty cool rig.
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Half the voltage drop....
It's better than that. Twice the voltage draws half the current, which causes one half the absolute (in Volts) voltage drop. But the voltage drop as a percentage of the line voltage is only one quarter and the energy loss in the line is one quarter, too, as P = i^2 * R. Increasing distribution voltage is a big win. -F
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Can you run the Midas on 240V? Half the voltage drop....
I dont know. I have to go to my storage unit and look at the power supply and see. If they will run on 220 it just means adding a 220 outlet to the FOH distro and thats easy.