Cable Knots

[FatherMurphy]

If the OP really doesn't want the cable to sag over the span, then perhaps using a board, pipe, or truss as a bridge would be a thought, instead of figuring out how to pull the cable itself tight. Obviously, one would have to make sure the bridge was securely rigged, but that would eliminate the sag and stress problems.

[epimetheus]

I've worked plenty of setups where the clove hitch method was used and it worked just fine. Granted I'm talking minimum 1.5" pipe and maximum 10/3 SO cable. I wouldn't do it for a permanent install, but for a temporary setup it should work fine.

Also, induction on the batten pipe is not an issue since both current carrying conductors have the same path around the pipe. The inductive forces cancel out, therefore no heating in the pipe. Good point though - you should never do this with single conductor cable.

[photoatdv]

Originally Posted by epimetheus

Also, induction on the batten pipe is not an issue since both current carrying conductors have the same path around the pipe. The inductive forces cancel out, therefore no heating in the pipe. Good point though - you should never do this with single conductor cable.

You lost me on the inductance on the pipe. I'm probably being stupid, but can somebody please explain? Thanks.

[Footer]

Choke the cable with tie-line or sash cord. If its a mult, use a small span-set or spectra loop.

Don't tie knots in cable.

[epimetheus]

Originally Posted by photoatdv

You lost me on the inductance on the pipe. I'm probably being stupid, but can somebody please explain? Thanks.

Think high school science. If you have a coil of single conductor wire and you connect a voltage source across the ends, current will pass through the wire. The current flowing in the circular pattern creates an electromagnetic force in the direction of the axis of the coil (in this case, the batten pipe). Any magnetic material placed inside this coil will "feel" the magnetic force. This force is not enough cause the coil to shoot off the batten pipe, but will cause heating in the pipe(induction). In the case of SO cable, you have current flowing from the source to the load via the hot wire and retuning via the neutral. Since both of these wires are in the same cable, they both have the same path. The opposite directions of current flow in the hot and the neutral cause the electromagnetic force due to the current flows to cancel each other out. Therefore no inductive heating in the pipe.

[Grog12]

Originally Posted by GreyWyvern

If you read the OP, he asked how to keep the cable from slipping down. A clove hitch does exactly that with out any chance of smashing, kinking, flattening, twisting, etc., the cable. The only way that would happen is if the cable itself was holding weight and causing the knot to tighten. Then there are other issues to worry about. I highly doubt that the weight of 20 feet of cable is enough to do any damage. The clove hitch works well because it puts no bends in the cable, the contact is distributed around the larger batten rather than one small point of tie line, and it is extremely easy to adjust to the exact height that you need. I just don't see how it is damaging to the cable.

Dave

You and I talking about the same clove hitch buddy?

The Clove Hitch

You're bending it around the pipe for one....much smaller than you really want to wrap standard 12-3 S/O. Even a 1.5" pipe diameter will put kinks in cable that has been wrapped around it.

Also if you have multiple runs of cable this is completly inefective...unless you're using one cable to tie off the rest.

[Dionysus]

Originally Posted by epimetheus

Think high school science. If you have a coil of single conductor wire and you connect a voltage source across the ends, current will pass through the wire. The current flowing in the circular pattern creates an electromagnetic force in the direction of the axis of the coil (in this case, the batten pipe). Any magnetic material placed inside this coil will "feel" the magnetic force. This force is not enough cause the coil to shoot off the batten pipe, but will cause heating in the pipe(induction). In the case of SO cable, you have current flowing from the source to the load via the hot wire and retuning via the neutral. Since both of these wires are in the same cable, they both have the same path. The opposite directions of current flow in the hot and the neutral cause the electromagnetic force due to the current flows to cancel each other out. Therefore no inductive heating in the pipe.

Again, DO NOT 'wrap' the cable around the pipe. Do not tie the cable itself into a clove hitch. It WILL cause damage to the cable. It is also against electrical code I do believe (I don't feel like checking to be 100%).
Use Tieline or rope, tie-ing it in a clove hitch around the cable. This will work. The Prusik or Sunday knotted line will also work very well. If you are worried about having everything 'rated' then the ideas of the truss or webbing-straps secured with shackles work well.