Cutting Conduits in Trenches

Seems like they would have a saw like the one used to cut cast of human arms or leggs for this.

Looks like there is room for a new invention here.

Have you tried a small rotary saw blade (slitting saw) in a portable (cordless) die grinder? This form may provide greater control options because you may use blocks to limit cutting depth etc..

Or you could loop the chain saw chain around the conduit; you'd need a longer chain, and proceed to sever the conduit similar to the way pipe is cut with chain

I have tried that but because of the shape of the teeth on the chain it is very hard to keep engagement with the sprocket. When the teeth bite they jerk the chain violently. I am looking at having the tips of the teeth coated with diamonds on the curved side. This will eleiminate the "Biting". Unlike the wood plane there is no way to control the "bite". Not all steels can be coated. Its like playing snakes and ladders and the only way to get to the end is to keep on keeping on.

Why do you need to cut open a conduit in the trench anyway? Why not go back to the nearest connection boxes on either end of the area to be dissected, disconnect one end and pull the cables out the other end? It sounds awful risky to me the contained cables. Are you a burgler tryng to breach a security system?

There is a chain you can adjust with a cutting egde on the inside of the wrench you turn around the PVC pipe and it cuts thru.

I have never used it but saw a city employees usiung one to cut thru water pipe to add a "T" for a new subdividion.

It looked just like a chain wrench but with the cutting edge on the inside. The edges of the chain act to limit to depth of the cut.

There are so many reasons not to do this...especially since these cables will be energized once the work is done. You did de-energize them first....right?

My solution to that problem:

Wrap around the conduit 16-14AWG nickel wire (heater wire) in a way that you can tighten it slowly through the cutting process, connected to a low voltage source, say 12V car battery through a 200 to 300W (or as calculated,) rheostat. Heat the wire carefully, to no more than 180-200ºC (It won't even turn red) by turning the rheostat from max "R" to min, and tightening the wire at the time. You really need two persons to do it safely... some practice required, so you know when to stop. It will go through the PVC like butter...

Take heed! the wire, at this length, is practically 0Ω, and forgetting to add the series resistance will cause the wire to fuse (at best...).

We call it "hot knife"...

Hope it helps.

Wangito.

One person can do if the wire ends are attached to a bow

When we run into this situation, we often just use a piece of construction string. The trick is to keep it moving, and move the cut around the conduit to avoid damaging the wires inside. Basically there is no single all useful solution to this problem, and it typically takes multiple approaches (scoring with a saw or knife, cutting with string, etc.) and good old fashioned elbow grease to get the job done.

Use your wire file like this:

When you have cut thru the conduit, slip a piece of curved sheet metal over the cut portion, to protect it from the file, and move it around the pipe as you cut.This will allow you to cut all the way around without injuring the wires inside.

HTRN

Field trick,

Use cotton string. You will go through a bit of string, but will not cut your cables.

Nice avatar <VBG>.

Oh, I forgot; I like your witicism signature. It means, "Don't let the bastards grind you down" doesn't it?