water infiltration in conduits in basement slab

[delkis]

i thought you might want to hear about this issue it is very interesting.

this is in a school-conduits imbedded in the slab were filled with water and the current carrying conductors inside the conduits were submerge in water. at times the water level is high and spilled from the conduits below the electric panels into the switchboard room, causing hazardous water condition in the area. also the conductors which were not rated as submersible may have been damaged and deteriorated in water.

we are going to replace all conduit/wiring and run overhead

 

[don_resqcapt19]

Re: water infiltration in conduits in basement slab

At least 90% of the below grade conduits that I have seen are filled with water for at least part of the conduit run. I have not seen any problems caused by the use of normal wet location wire in these water filled conduits.
Don

 

[delkis]

Re: water infiltration in conduits in basement slab

there have been incident of arching and partial power outages

 

[don_resqcapt19]

Re: water infiltration in conduits in basement slab

Most likely caused by a combination of insulation damge when the wire was installed and the water.
Don

 

[jrdsg]

Re: water infiltration in conduits in basement slab

don is right, buried pipe almost always fills with water. often before you get to pull through it.

 

[iwire]

Re: water infiltration in conduits in basement slab

buried pipe almost always fills with water. often before you get to pull through it.

Yes that is how it is in this area also, and as Don has said it seems to work fine if the insulation was not damaged on the install.

Along this line Rhode Island will not allow any fire alarm conductors to be run underground other than the municipal Master box wires.

The filling with water before pulling can be a problem for us once winter comes, more than once we have had the water freeze up and prevent conductor installation.

 

[pierre]

Re: water infiltration in conduits in basement slab

A funny story

As an apprentice years ago I was asked to sit in the phone closet with a two way radio. The 4 in. pipes had water that was frozen and it was bitterly cold out. The run was about 500 feet. I was to listen for any sound while they were using a truck mounted compressor to try and blow out the lines. They were desperate to install the phone lines and the pipe had frozen.
I got bored quickly while waiting and was not paying close attention. All of a sudden I hear this strange noise and at first was not sure where it was coming from. As soon as I realized it was the sound of the compressed air, water and frozen ice, I tried to get out of the room. But.. I was not fast enough. The ice and water came gushing out of the pipe at a great speed and hit the ceiling spraying all over me.

Pierre