Sign in with
Sign up | Sign in
Your question

Safe to drive cars over power/speaker cable?

Last response: in Home Audio
Share
Anonymous
June 8, 2005 4:16:20 PM

Archived from groups: rec.audio.pro (More info?)

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
Anonymous
June 8, 2005 5:01:15 PM

Archived from groups: rec.audio.pro (More info?)

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.
Anonymous
June 8, 2005 5:11:58 PM

Archived from groups: rec.audio.pro (More info?)

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
Related resources
Anonymous
June 8, 2005 5:16:40 PM

Archived from groups: rec.audio.pro (More info?)

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
Anonymous
June 8, 2005 5:24:08 PM

Archived from groups: rec.audio.pro (More info?)

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
Anonymous
June 8, 2005 8:09:13 PM

Archived from groups: rec.audio.pro (More info?)

Bobby_M <rmierzej@telcordia.com> 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."
Anonymous
June 8, 2005 8:53:49 PM

Archived from groups: rec.audio.pro (More info?)

Bobby_M <rmierzej@telcordia.com> 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."
Anonymous
June 9, 2005 1:06:50 AM

Archived from groups: rec.audio.pro (More info?)

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).
Anonymous
June 9, 2005 1:20:48 AM

Archived from groups: rec.audio.pro (More info?)

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
Anonymous
June 9, 2005 7:58:51 AM

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:

> Bobby_M <rmierzej@telcordia.com> 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
Anonymous
June 9, 2005 8:21:12 AM

Archived from groups: rec.audio.pro (More info?)

On 8 Jun 2005 16:09:13 -0400, kludge@panix.com (Scott Dorsey) wrote:

>This is a code violation

A possibly funny counterpoint on "safety" is at a home
construction site. You'll see stuff to curl the short ones
all over the place, *especially* where you're not looking.

Code only apply when anybody's looking, or if some
civilian gets hurt. Your point that *we* need to be code
is especially important. Mostly nobody's looking; that
leaves us to do right.

Thanks, as always,

Chris Hornbeck
"For a change, she got out,
'Fore he hurt her bad.
Took her records and clothes,
And pictures of her boy." -Elliott Smith
Anonymous
June 9, 2005 1:27:41 PM

Archived from groups: rec.audio.pro (More info?)

Dale Farmer <dale@cybercom.net> 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."
Anonymous
June 9, 2005 3:10:16 PM

Archived from groups: rec.audio.pro (More info?)

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
Anonymous
June 9, 2005 4:52:18 PM

Archived from groups: rec.audio.pro (More info?)

On 8 Jun 2005 13:24:08 -0700, Bobby_M <rmierzej@telcordia.com> 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
Anonymous
June 9, 2005 4:52:19 PM

Archived from groups: rec.audio.pro (More info?)

Charles Krug <cdkrug@worldnet.att.net> wrote:
>On 8 Jun 2005 13:24:08 -0700, Bobby_M <rmierzej@telcordia.com> 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."
Anonymous
June 9, 2005 5:13:38 PM

Archived from groups: rec.audio.pro (More info?)

Charles Krug wrote:
> On 8 Jun 2005 13:24:08 -0700, Bobby_M <rmierzej@telcordia.com> 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
Anonymous
June 9, 2005 5:16:37 PM

Archived from groups: rec.audio.pro (More info?)

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
Anonymous
June 9, 2005 5:16:38 PM

Archived from groups: rec.audio.pro (More info?)

George Gleason <g.p.gleason@att.net> 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."
Anonymous
June 9, 2005 5:56:29 PM

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:
> George Gleason <g.p.gleason@att.net> 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
Anonymous
June 9, 2005 6:28:19 PM

Archived from groups: rec.audio.pro (More info?)

On Thu, 09 Jun 2005 09:51:45 -0400, Scott Dorsey wrote:

> George Gleason <g.p.gleason@att.net> 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.
Anonymous
June 9, 2005 9:09:04 PM

Archived from groups: rec.audio.pro (More info?)

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
!