Shopsmith Forums

There will be no work in the shop today. Christmas projects will just go on "temporary hold". Today it is a new electrical feed. No, it will not be a new 220v feed to the shop. This one will serve the pool pump, pool lights and pool heater. What a terrible time to have an underground cable short develop.

What a terrible time to be trenching. It is cold and damp outside but the sun has come up and the chill is dissipating. Fortunately we don't have ground freeze here. Hi Ho, Hi Ho, it's off to work I go.

Underground shorts and breaks can be almost 100% prevented by putting power cables in conduit. I've seen plenty of underground cable breaks, but none of them that failed were in conduit. The ones in conduit can be expected to outlast the user many times.

+1 on this. it is a false economy to use direct burial over conduit. at least with conduit IF you have to replace a wire there is no digging called for.i had to relpace 100 feet for my well because the well driller used direct burial so i learned my lesson.

garys wrote:Underground shorts and breaks can be almost 100% prevented by putting power cables in conduit. I've seen plenty of underground cable breaks, but none of them that failed were in conduit. The ones in conduit can be expected to outlast the user many times.

All the underground wire on my property is in conduit. And, on top of that, it is all copper wire.
Next to my property the city has been patching their direct burial aluminum wire every year for decades. It had more patches than original wire left so last summer they finally put in new wire with conduit. If they had done that the first time, all those years of repairs wouldn't have been needed.
There is an old saying, "You can do it right, or you can do it over."

Up here, the ground freezes and thaws every year. Wherever there are rocks or anything else hard in the ground, those hard things will break the wire with enough freeze-thaw cycles.

Sorry guys but I am here to tell you that buried conduit does not last forever. The work that is being done today and tomorrow involves short circuits in two feeds both in conduit.

I believe this may have a lot to do with the soil here. About 6" down it becomes as hard as concrete and the soil above that retains a lot of moisture.

The stuff being pulled out is s little more than rust.

Rust is why you use plastic conduit underground.

garys wrote:Rust is why you use plastic conduit underground.

I can't imagine using metal conduit underground. I have two lines out to my shop. Both are plastic. One is the power and the other is a spare in case I want to run something else

Depending on when it was installed, and codes of the state involved, metal might have been required. I may be mistaken, but I seem to recall that certain depths of burial had different requirements here in Connecticut when I had my pool built.

If I were to bury metal conduit, it would NOT be EMT, but RMC(pipe).

I would prefer PVC.

However I think natural gas line liner would be more durable.

I used the conduit that I did because I was guided by a well established licenced contractor here in Tucson. The conduit that I used is required here, by code, for the depth of my trench. I did not want to bury 4' down; not in this ground which is very hard to dig in.

At different depths there are different requirements. At some depth there needs to be a gravel base beneath the conduit and a gravel cover before dirt can be used.

As for the original (rotted out)installation, that was done by the pool contractor back in 1978/79 , I don't know what the code was then but this contractor is still installing pools here in the Tucson area, if that means anything.

At any rate, the new conduit is buried, the wires pulled and all the lights, blowers and pump have been checked out. Just need to rewire the control panel and the job will be done before the day is out.