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Cat 5 cable as electrical wire

R

Robroy

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Jun 21, 2006
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#1
So, the dad in my Family Band is an electrician. He built his own can lights using a plastic pipe, four coffee cans with standard light bulb screw in's and wires it to a four switch enclosed outlet on the bottom section of a microphone stand. Each of the four cans has a 150 watt bulb.

He did the math and discovered he could wire the whole thing with cat five cable, allowing lots of "plug & play" flexibility.

He completed this about 8 months ago, before we were gigging. I brought it up on a musicians site in the lighting section and the posters came unglued. They wanted him either arrested or shot because it is a ridiculous idea.

Meanwhile, we started gigging about five or six months ago and have used those lights regularly. All four bulbs. The wiring doesn't even get remotely warm.

I get the feeling some things sound crazy, but are not. And vice versa...
 
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#3
M0ses said:
Just because you haven't had a problem yet doesn't mean it won't happen. It's true, most electrical specs demand significant overkill, but they do that for a reason. A good reason. 120V isn't anything to F around with and it's not worth taking risks with. I wouldn't plug those things in, personally.
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Well, the insulation is ample, the wires are cool. So, is there some risk with electromagnetism or some other force of nature causing the electrons to try to run free that doesn't exist with "approved" electrical wire?
 
#4
This is a non standard application for Cat 5 wire. In industry and code/ethics wise this is a no-no. On the other hand, amperage wise your dad is correct and carefully used it will be fine. Okay for a serious DIYer but showing this to people not well educated in electricity sets a bad example by breaking convention. I hope this explains why you got pummeled over the idea although it actually works well. I am not sure what the insulation rating is for Cat 5 cable but in normal use it sees about 5 volts not 110...
 
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#6
Spirit of Ox said:
The first thing that alarms me about this would be the gauge of wring. Cat5 is low voltage so the wiring might be to thin a gauge for this application.
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That's where we get into him "doing the math".

I've noticed with a lot of things in life it can be fun to go "back to basics" and rediscover WHY the rules of tha particual subject exist. e.g. for electrical purposes, a dead giveaway that wiring is too thin is that it gets warm. Though this cat5 wire is stone cold after hours of use.

I installed Cibie pencil beams on my Opel GT for road rallying back when I was 22 and, though I had the sense to use a relay, attached to my high beams, I used speaker wire to run the low voltage electricity to the 55 watt bulbs. A few miles into my drive the Cebie's went out. I opened the hood and the insulation had melted off the speaker wire, effectively shutting them down (the fuse, I should say).

And that's another important point. Low voltage needs thicker wire to supply the same energy. This may be the secret for why "low voltage" cat-5 wire works for this.
 
#7
bassmeknik said:
This is a non standard application for Cat 5 wire. In industry and code/ethics wise this is a no-no. On the other hand, amperage wise your dad is correct and carefully used it will be fine. Okay for a serious DIYer but showing this to people not well educated in electricity sets a bad example by breaking convention. I hope this explains why you got pummeled over the idea although it actually works well. I am not sure what the insulation rating is for Cat 5 cable but in normal use it sees about 5 volts not 110...
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So, it's not crazy! It's not a physics problem. It's a culture problem. ;)

BTW, He's the dad of the family. I'm the only member not in the family. I'm ten years older than him. I didn't really make that very clear.
 
#8
bassmeknik said:
On the other hand, amperage wise your dad is correct and carefully used it will be fine. .
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I think you mean current? No, CAT5 wire is definitely not ok for 150W x 4 = 600W. (!!) Would you run your bass amp with a wire as thin as a single CAT5 strand? That's madness.

The maximum current spec for CAT5 is 0.577 Amps. 600W at 110V is over 5 Amps. That's running it at 10 times more current the spec.

If this setup causes a fire, both you and your dad would both be liable for damages. What if a fire happened and someone was killed?
 
#9
mactac said:
I think you mean current? No, CAT5 wire is definitely not ok for 150W x 4 = 600W. (!!) Would you run your bass amp with a wire as thin as a single CAT5 strand? That's madness.

The maximum current spec for CAT5 is 0.577 Amps. 600W at 110V is over 5 Amps. That's running it at 10 times more current the spec.
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So why is the wiring cold after several hours of use? And I'll have to ask him about his math.
 
#10
As someone with a degree in electrical engineering, several years of electrical installation work, a pretty good familiarity with the National Electric Code and about 30 years experience in theatrical stage lighting, I can tell you that there are an awful lot of things that you can do but shouldn't.

While the wire guages may be doing fine for the current load, the insulation is nowhere near rated for the voltage. I don't know what connectors he's using, but if they're normal RJ45 connectors, they're not rated for the voltage either. If they're some other type, they're not designed to work with CAT-5 wire.

I've worked in countless theaters over the years and have seen lots of cobbled-together effects. Many of them worked just great until the day that they didn't. Get the picture? If the Family Band (I remember them from your other posts) plays a gig in a public space and that turns out to be the day that the CAT-5 lets the magic smoke out, I just hope they have a lot of insurance.

I'm not going to tell you not to do what you're doing, I'm just going to tell you it's a risk that's not worth taking, IMO.
 
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#11
BTW, my father told me many decades ago that the voltage levels in those wires on the large monster power lines running from dams is pretty much as high as they can get it. He said that if they bump in any more that where the wires sharply change their angle at the pole the electrons would not stay with the wire, but shoot out into the atmosphere, like a roller coaster flying off the track. He worked on the electronics of missiles in silos across the midwest.
 
#12
Lo-E said:
I've worked in countless theaters over the years and have seen lots of cobbled-together effects. Many of them worked just great until the day that they didn't. Get the picture?
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But what causes that to happen? Every failure is caused by something. What changes to cause the wire to suddenly not work? I'm especially puzzled by this if the wire is stone cold during use. Your comments about the plugs is concerning, because his whole reason for doing this is to make connecting everything light and easy.

BTW, I'm really NOT trying to make the case that this is just a-ok. Rather, I find myself in WAY too many instances of cutting the end off the ham. I'm trying to stop doing that.
 
#13
Well I looked here; http://www.powerstream.com/Wire_Size.htm and noticed that a 24 gauge wire used for power transmission is rated for only .577 amps where if used for internal chassis wiring it is rated for 3.5 amps. Clearly this does not meet the ratings for power transmission, however I agree it probably runs cool and is safe if you are careful and remember the task you are using it for is greater than designed. Don't set heavy things on it or restrict air flow around it or risk of failure is greater.

In my opinion you should use fuses or circuit breakers appropriate for each bulb in line with each of the 4 channels of light. Then if the wire fails the fuse or breaker will protect you, your gear, and the venue you play in from that thing.


Back in the 70's my pals and I experimented with home made flash pots (long before the Great White accident) and used them in clubs regularly THEN. Be very careful using non standard wiring today, you could be named as the arson of a fire that wasn't even caused by your system, but is ruled the cause due solely to it being a non-conforming device. Just my .02
 
#14
Robroy said:
So why is the wiring cold after several hours of use? And I'll have to ask him about his math.
Click to expand...


There are 3 problems:

1. The guage of the wire. This is what would cause the heat. To figure out if it's a problem, you would have to feel the wire along it's entire length, not just in one place
2. The connector. electrical connectors are designed so that the chance of a short is very rare. CAT5 connectors fail all the time. I can't count how many I've had go bad on me.
3. This is the big one: insulation. The amount of insulation/isolation is extremely low. An Arc from one wire to the other could cause a fire rather easily.
 
#15
Robroy said:
But what causes that to happen? Every failure is caused by something. What changes to cause the wire to suddenly not work? I'm especially puzzled by this if the wire is stone cold during use. Your comments about the plugs is concerning, because his whole reason for doing this is to make connecting everything light and easy.

BTW, I'm really NOT trying to make the case that this is just a-ok. Rather, I find myself in WAY too many instances of cutting the end off the ham. I'm trying to stop doing that.
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CAT5 cable fails all the time. It's not meant to be used, moved, bendt, etc. A kick, a bend, or a hotspot could cause a short or arc.
 
#16
mactac said:
There are 3 problems:

1. The guage of the wire. This is what would cause the heat. To figure out if it's a problem, you would have to feel the wire along it's entire length, not just in one place
2. The connector. electrical connectors are designed so that the chance of a short is very rare. CAT5 connectors fail all the time. I can't count how many I've had go bad on me.
3. This is the big one: insulation. The amount of insulation/isolation is extremely low. An Arc from one wire to the other could cause a fire rather easily.
Click to expand...
Thank you!

I'm sending your response to him.
 
#17
The current draw (in amps...) of a 150 watt bulb is 1.36 amps in a 110 volt system. Using the 8 conductors as 4 pairs you may be able to (obviously you can...) use Cat 5 in this application. However the insulation properties are not as good against abrasion and although this works I wouldn't take it to one of my venues out of respect for the owner. I also take home made non UL approved gear to work (with circuit protection built in)(pre-amp and effects pedal) so I am a bit of a contradiction in terms myself. However all of my DIY devices follow normal convention as far as wire size and type, etc. I did give up on the flash pots decades ago...
 
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#18
One problem with CAT5 is when it's disconnected the contacts are exposed (they are male/male). If that wire is charged you now have a potentially lethal situation. That's why power cords are always male/female.

On the other hand, I've always wondered why instrument cables aren't CAT5. Cheap, easy to make, solid contact and much greater wiring options than the old quarter inch. Sounds like a winner to me.
 

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