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#1
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Safe to drive cars over power/speaker cable?
I'm running sound for a large polo match and have previously suspended
both power and speaker cable over the main parking lane between a tree and the speaker lift. This is really a pain in the butt and there's always the chance a large catering box truck will nab it. I'm running two lengths of 10/3 SJ from the generator for power and two runs of 12/2 low voltage zip for my 70v runs. Would laying these side by side across the driving lane be ok? This is on grass so I figure the cable would most likely be pressed into the turf. I'm thinking [SJ, zip, zip, SJ]. I estimate only car traffic since pulling it over to the board and amps could be done last minute after the caterers are gone. Flying the cable, on the other hand, is usually setup the day before. Thoughts? Bobby |
#2
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I would guess 10/3 and 12/2 in grass would be pretty safe but if you
can find some wood to put across the car path and place the cable runs between two pieces it might make you feel better. |
#3
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Bobby_M wrote:
I'm running sound for a large polo match and have previously suspended both power and speaker cable over the main parking lane between a tree and the speaker lift. This is really a pain in the butt and there's always the chance a large catering box truck will nab it. I'm running two lengths of 10/3 SJ from the generator for power and two runs of 12/2 low voltage zip for my 70v runs. Would laying these side by side across the driving lane be ok? This is on grass so I figure the cable would most likely be pressed into the turf. I'm thinking [SJ, zip, zip, SJ]. I estimate only car traffic since pulling it over to the board and amps could be done last minute after the caterers are gone. Flying the cable, on the other hand, is usually setup the day before. Thoughts? Bobby I do "lots" of outdoor car shows yes your cable will take a beating but I have not had a SO cord set fail due to a car (or hundreds of cars ) driving over it the orange home depot crap WILL fail George |
#4
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Bobby_M wrote:
I'm running two lengths of 10/3 SJ from the generator for power and two runs of 12/2 low voltage zip for my 70v runs. Would laying these side by side across the driving lane be ok? This is on grass so I figure the cable would most likely be pressed into the turf. I'm thinking [SJ, zip, zip, SJ]. I estimate only car traffic since pulling it over to the board and amps could be done last minute after the caterers are gone. Flying the cable, on the other hand, is usually setup the day before. Thoughts? This is a code violation unless you put a cable tray overtop. The trays can be rented from any place that rents film sound and lighting gear, or you can buy them from a safety supply place, or you can make your own out of wood. Whoever is renting the generator will probably also have trays available. They aren't expensive... they are a lot cheaper than damaged cables. Incidentally, while 12/2 zip seems like a great way to move 70V stuff around, it turns out to _never_ wrap back again properly. After a couple events, you find you can never roll the stuff up flat. I was really delighted when the hardware stores around here first started carrying it, but after a couple years of trying it I have lost that enthusiasm. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
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I can't remember if I used SJ or SO now that I think if it. The cable
is already on site. It's not home depot orange, it's Carol from a real electrical supply. SO is the 600 volt version with the heavier insulation right? If it's any indication, I remember the cable bing about 1/2" to 5/8" in diameter. The 12/2 I'm using for the 70v speaker runs is from Home Depot though and it's the landscape lighting stuff. I figured it made a great outdoor cable for a 1000' line of horns without spending hundreds of dollars since it's UV protected. This is a once a year thing. Maybe I ought to put the two runs of 12/2 zip inside 1/2" galvanized conduit? Bobby |
#6
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I know what you mean. I ended up swiping a larger wooden cable reel
from the electrical supply shop and rigging a sweet portable reel stand out of an old shopping cart. I have two 600' runs that emminate from the center of the 1000' field. I roll one length back up, then attach the other and roll that one. I have 5 switchcraft push-to-lock connectors down each length and they occassionally get caught in the weeds when i'm trying to reel it back in, but i usually have a helper run to untangle it. Bobby |
#7
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Scott, by the way.. I haven't seen an inspector show up to this event
in the last 3 years but I'm curious as to which "code" you're referring to. NEC? Does this also apply to temporary installations? There is no way I'd be able to integrate a tray. This is a span of about 60 feet and the mix end is on a hydraulic scissor lift. Like I said, I'm all for nixing the idea because it's a lot of extra work. If I had to guess, maybe 50 cars will drive over my cable total for the day. I like the previous idea of perhaps flanking the cable with some furring strips where the wheels will hit and maybe running some yellow/black gaffers tape down the line. Thoughts? Bobby |
#8
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Bobby_M wrote:
Scott, by the way.. I haven't seen an inspector show up to this event in the last 3 years but I'm curious as to which "code" you're referring to. NEC? Does this also apply to temporary installations? Yes. And the grounding procedures for temporary installations are very different than for installed facilities. There is no way I'd be able to integrate a tray. This is a span of about 60 feet and the mix end is on a hydraulic scissor lift. Like I said, I'm all for nixing the idea because it's a lot of extra work. If I had to guess, maybe 50 cars will drive over my cable total for the day. I like the previous idea of perhaps flanking the cable with some furring strips where the wheels will hit and maybe running some yellow/black gaffers tape down the line. The only part you need to put the tray over is the part where the cars are driving. If you're going over an active roadway, you need the tray in the roadway area. If the whole 60 feet is an active roadway or a parking lot, that's bad and you need to move it. But I bet you need less than ten feet of the stuff. The stuff is really just a couple triangular wooden or plastic strips, with some plywood or steel over the top. It's not anything too expensive or esoteric. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#9
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Bobby_M wrote:
I'm running sound for a large polo match and have previously suspended both power and speaker cable over the main parking lane between a tree and the speaker lift. This is really a pain in the butt and there's always the chance a large catering box truck will nab it. I'm running two lengths of 10/3 SJ from the generator for power and two runs of 12/2 low voltage zip for my 70v runs. Would laying these side by side across the driving lane be ok? This is on grass so I figure the cable would most likely be pressed into the turf. This is going to sound like a zany idea (because it is), but what about using something like a gas-powered edger to cut the grass and dig a tiny trench/ditch that's around 2 inches deep, then laying the cables in the hole? If they stay, that would at least keep the car wheels off of them (provided it's not muddy). - Logan |
#10
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Scott Dorsey wrote: Bobby_M wrote: Scott, by the way.. I haven't seen an inspector show up to this event in the last 3 years but I'm curious as to which "code" you're referring to. NEC? Does this also apply to temporary installations? Yes. And the grounding procedures for temporary installations are very different than for installed facilities. There is no way I'd be able to integrate a tray. This is a span of about 60 feet and the mix end is on a hydraulic scissor lift. Like I said, I'm all for nixing the idea because it's a lot of extra work. If I had to guess, maybe 50 cars will drive over my cable total for the day. I like the previous idea of perhaps flanking the cable with some furring strips where the wheels will hit and maybe running some yellow/black gaffers tape down the line. The only part you need to put the tray over is the part where the cars are driving. If you're going over an active roadway, you need the tray in the roadway area. If the whole 60 feet is an active roadway or a parking lot, that's bad and you need to move it. But I bet you need less than ten feet of the stuff. The stuff is really just a couple triangular wooden or plastic strips, with some plywood or steel over the top. It's not anything too expensive or esoteric. IF the ground is soft ( no rocks or gravel that could cut the cable jacket ) you could just lay the cable on the ground, water it to soften the soil a bit, then just lay a couple sheets of plywood on top of it. First few cars to drive over it will press it into the mud you created, and then the plywood will keep the little patch of mud from turning into a patch of quicksand. Renting some proper yellowjacket cable protectors from the generator vendor is, of course, the better way to go. You say less than 60 cars in a day, which is, as these things go, light traffic. If some of these cars are really heavy trucks, or forklifts, then you need to have something stronger than a sheet of plywood. Also, 70volt speaker distribution cable falls under the NEC rules for protection and grounding purposes. It has to be under fifty volts to fall into the low voltage exceptions. --Dale |
#11
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At least rent some 1x12 planks (the kind they use for construction
scaffolding) and cover the cables with them in the roadway. Shouldn't cost more than a few bucks (literally). |
#12
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#13
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less than ten feet of the stuff.
The stuff is really just a couple triangular wooden or plastic strips, with some plywood or steel over the top. It's not anything too expensive or esoteric. --scott at the one farm and construction equipment show I do where I have bulldozers and such driving over my cables I cover them with angle iron george |
#14
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On 8 Jun 2005 13:24:08 -0700, Bobby_M wrote:
Scott, by the way.. I haven't seen an inspector show up to this event in the last 3 years but I'm curious as to which "code" you're referring to. NEC? Does this also apply to temporary installations? There is no way I'd be able to integrate a tray. This is a span of about 60 feet and the mix end is on a hydraulic scissor lift. Like I said, I'm all for nixing the idea because it's a lot of extra work. If I had to guess, maybe 50 cars will drive over my cable total for the day. I like the previous idea of perhaps flanking the cable with some furring strips where the wheels will hit and maybe running some yellow/black gaffers tape down the line. Thoughts? Bobby The NEC has a specific section dealing with temporary installations, mostly construction sites, but outdoor events are addressed. PHotocopy out the relavant bits from the reference section of your local library. There's also an "NEC Handbook," also published by NFPA, that explains things if you're not a PhD in EE |
#15
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Charles Krug wrote:
On 8 Jun 2005 13:24:08 -0700, Bobby_M wrote: Scott, by the way.. I haven't seen an inspector show up to this event in the last 3 years but I'm curious as to which "code" you're referring to. NEC? Does this also apply to temporary installations? There is no way I'd be able to integrate a tray. This is a span of about 60 feet and the mix end is on a hydraulic scissor lift. Like I said, I'm all for nixing the idea because it's a lot of extra work. If I had to guess, maybe 50 cars will drive over my cable total for the day. I like the previous idea of perhaps flanking the cable with some furring strips where the wheels will hit and maybe running some yellow/black gaffers tape down the line. Thoughts? Bobby The NEC has a specific section dealing with temporary installations, mostly construction sites, but outdoor events are addressed. PHotocopy out the relavant bits from the reference section of your local library. There's also an "NEC Handbook," also published by NFPA, that explains things if you're not a PhD in EE the code really is only a guide , it is not the word of god ity is a minimum that applies everywhere your local inspector will be "thye word of God" I had one that made me tie yellow saftey caution tape bows on my thousands of feet of cable every two feet one at cornell university(Barton Hall) made me remove all my black wire and replace it with day glo orange my speaker runs are milspec stainless steel braid under some really tough plastic it is for battlefeild use and you can litterly drive tanks over it it was surplus feild communications cable from the Korean war it is 6 connductor 18 guage each that I twist into a pair or three condutors each on nice military spools there are about 600 feet each be careful if your running such long cable and there is a very real problem with hf reflections in the cable driving your amps into ossilation my crest 8002, and mackie 1400i's could not reject it and would protect my powerlights,behringers and powersoft don't seem to mind George George |
#16
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if you lay out cable at a horse show it need to be covered or buried
where ever a horse might see it they will see the cable as a snake and freak flipping out also cattle,and other animals can be electrocuted by voltages we would not even notice be very alert to this if you around multi million dollar race horses George |
#17
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Dale Farmer wrote:
Also, 70volt speaker distribution cable falls under the NEC rules for protection and grounding purposes. It has to be under fifty volts to fall into the low voltage exceptions. However, this gets modified by a lot of individual localities. There are places where 70V lines are considered class I wiring and places where they aren't. Around here, we have adjacent counties with different rules. On one side of Rt. 60 you see buildings with 70V systems, on the other side of the street you see buildings with 25V constant-voltage systems instead. Local code is not always identical to the NEC, and unfortunately this is one the places where there are a lot of changes. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#18
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Charles Krug wrote:
On 8 Jun 2005 13:24:08 -0700, Bobby_M wrote: The NEC has a specific section dealing with temporary installations, mostly construction sites, but outdoor events are addressed. PHotocopy out the relavant bits from the reference section of your local library. There's also an "NEC Handbook," also published by NFPA, that explains things if you're not a PhD in EE It doesn't explain things enough, though. All the time you read through the NEC and hit yourself on the head and say "Why the hell do they require THAT?" Sometimes I can figure out why, sometimes I cannot. There's a whole section on impedance-grounded systems. Why would anyone ever want to do that? I don't know. The grounding rules seem arbitrary and arcane until you sit down and figure out that a lot of them are for eliminating ground loops in the power system. But the book doesn't explain that. Somebody should really come out with a proper explanation of the NEC rules. --scott (Who is only an MS in EE because his department quit before he finished) -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#19
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George Gleason wrote:
if you lay out cable at a horse show it need to be covered or buried where ever a horse might see it they will see the cable as a snake and freak flipping out I seem to have a bird living in my house. The bird does NOT like heavy cables. It is very difficult to do any sort of work with the bird out. Also the bird does not like choral music. Orchestral stuff is okay, but he seems to be creeped out by all of these invisible people singing around him. also cattle,and other animals can be electrocuted by voltages we would not even notice This surprises me, as someone who as a child once touched an electric fence. They don't seem to harm cattle, but you can believe I noticed it. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#20
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Scott Dorsey wrote:
George Gleason wrote: if you lay out cable at a horse show it need to be covered or buried where ever a horse might see it they will see the cable as a snake and freak flipping out I seem to have a bird living in my house. The bird does NOT like heavy cables. It is very difficult to do any sort of work with the bird out. Also the bird does not like choral music. Orchestral stuff is okay, but he seems to be creeped out by all of these invisible people singing around him. also cattle,and other animals can be electrocuted by voltages we would not even notice This surprises me, as someone who as a child once touched an electric fence. They don't seem to harm cattle, but you can believe I noticed it. --scott I am going by what the horse show people told me I have no other source of info on this George |
#21
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On Thu, 09 Jun 2005 09:51:45 -0400, Scott Dorsey wrote:
George Gleason wrote: also cattle,and other animals can be electrocuted by voltages we would not even notice This surprises me, as someone who as a child once touched an electric fence. They don't seem to harm cattle, but you can believe I noticed it. Well since they don't wear shoes, they're probably grounded better than humans most of the time. I've seen several news stories about people walking their dogs in metropolitan areas & the dogs getting shocked or even electrocuted when walking over the steel plates used to cover construction areas in the sidewalks. Turns out someone was not as careful as they should have been & juice was getting to the plate somehow.Seems like I remember one woman getting injured pretty badly when she tried to pick her dog up. |
#22
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thanks for all the feedback guys...
After consulting with the owner of the farm, he decided he'd spring for the speedbumps with the integrated wire channel underneath. This is an annual event and he's been investing in new equipment as necessary over the years. He owns the generators, the 70v horns, some big Altec multicells, and all the long cable that I built custom to the field's needs. What's another couple hundred right? Someone mentioned trenching... I think this guy spent thousands to have his field seeded and continues to throw tons of money to keep this huge field looking like a golf fairway. Bobby |
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