Underground conduit to Garage

nobleea · 19-06-2012, 04:50 PM

We are rebuilding a detached garage and I want to run the cable and TV in an underground conduit. We will also be running a separate conduit for power back to the garage from house. I know it has to be 3' deep or more.
What about conduit expansion joints? Are these required at surface? From what I have seen in other installations, it is not, but wanted to check.

This will be 3/4" conduit for both.

lat · 19-06-2012, 05:32 PM

When I upgraded our electrical, I had an electrician install a mast on the garage with the main panel in the garage, and then run phone, cable and power underground from the garage to the house. They just used underground grade cables with no conduit. No problems 3 years later...

sundance · 19-06-2012, 09:27 PM

A good idea is to lay a treated 2x4 above the cable in the trench, this way if somebody is shoveling they will hit the 2x4 1st without damaging the wire.

Not sure about expansion joints though. On a short run the conduit itself shouldn't expand or contract too much, however the frost could heave it.

SP59 · 19-06-2012, 10:47 PM

You don't have to dig a trench three feet deep. 18 inches for protected cable or 24 inches for unprotected cable. The city may want to inspect your trench. (If the trench isn't running under vehicular traffic)

source: http://www.capp.ca/getdoc.aspx?DocId=146773&DT=PDF

sundance · 20-06-2012, 07:44 AM

They also have warning tape that is typically installed 1/2 way between the ground and the wires, but a 2x4 is cheaper and will stop a shovel nicely. Sure you might know where the wire is, but when you sell the house then that knowledge is probably lost.
http://www.seton.ca/tapes/undergroun...king-tape.html

lat · 20-06-2012, 08:06 AM

We used warning tape. The electrician recommended having the tape poke out just a bit where it comes up and into the house, so that people know that it is there.

JJMorrocco · 20-06-2012, 08:18 AM

When my dad built his garage some 30 years ago, he laid a 3" pvc pipe from the garage to the house direct into the basement. In the conduit he put hot and cold water lines, as well as telephone, and intercom ( I think his power is separate). This conduit came in very handy when he added an alarm to his garage as well years later when we also had cable satellite dish(es) added. Don't forget to leave a piece of string in the line to pull additional lines later on.

nobleea · 20-06-2012, 08:47 AM

Quote:

Originally Posted by SP59

You don't have to dig a trench three feet deep. 18 inches for protected cable or 24 inches for unprotected cable. The city may want to inspect your trench. (If the trench isn't running under vehicular traffic)

source: http://www.capp.ca/getdoc.aspx?DocId=146773&DT=PDF

I don't think that link is valid for residential electric.

This link from Epcor says between 900-1200mm below grade (sec 2.03)
http://corp.epcor.com/SiteCollection...esidential.pdf

Yes, as part of the electrical permit, the city wants to inspect the conduit in the trench before it is backfilled.

SP59 · 20-06-2012, 11:34 PM

That link from Epcor seems to be for service from the street to a property vs. service from say a residence to a detached garage.

19-06-2012, 04:50 PM	#1
nobleea Addicted to C2E Join Date: Apr 2007 Location: Edmonton	Underground conduit to Garage We are rebuilding a detached garage and I want to run the cable and TV in an underground conduit. We will also be running a separate conduit for power back to the garage from house. I know it has to be 3' deep or more. What about conduit expansion joints? Are these required at surface? From what I have seen in other installations, it is not, but wanted to check. This will be 3/4" conduit for both. Last edited by nobleea; 19-06-2012 at 05:34 PM..

19-06-2012, 05:32 PM	#2
lat Addicted to C2E Join Date: Jan 2007	When I upgraded our electrical, I had an electrician install a mast on the garage with the main panel in the garage, and then run phone, cable and power underground from the garage to the house. They just used underground grade cables with no conduit. No problems 3 years later... __________________ done.

19-06-2012, 10:47 PM	#4
SP59 Partially Addicted to C2E Join Date: Jan 2012 Location: Sherwood park	You don't have to dig a trench three feet deep. 18 inches for protected cable or 24 inches for unprotected cable. The city may want to inspect your trench. (If the trench isn't running under vehicular traffic) source: http://www.capp.ca/getdoc.aspx?DocId=146773&DT=PDF Last edited by SP59; 19-06-2012 at 11:05 PM.. Reason: ad bracketed material and source

20-06-2012, 08:06 AM	#6
lat Addicted to C2E Join Date: Jan 2007	We used warning tape. The electrician recommended having the tape poke out just a bit where it comes up and into the house, so that people know that it is there. __________________ done.

19-06-2012, 09:27 PM	#3
sundance Addicted to C2E Join Date: Mar 2007 Location: City of Champions	A good idea is to lay a treated 2x4 above the cable in the trench, this way if somebody is shoveling they will hit the 2x4 1st without damaging the wire. Not sure about expansion joints though. On a short run the conduit itself shouldn't expand or contract too much, however the frost could heave it.

20-06-2012, 07:44 AM	#5
sundance Addicted to C2E Join Date: Mar 2007 Location: City of Champions	They also have warning tape that is typically installed 1/2 way between the ground and the wires, but a 2x4 is cheaper and will stop a shovel nicely. Sure you might know where the wire is, but when you sell the house then that knowledge is probably lost. http://www.seton.ca/tapes/undergroun...king-tape.html

20-06-2012, 08:18 AM	#7
JJMorrocco Addicted to C2E Join Date: Apr 2008	When my dad built his garage some 30 years ago, he laid a 3" pvc pipe from the garage to the house direct into the basement. In the conduit he put hot and cold water lines, as well as telephone, and intercom ( I think his power is separate). This conduit came in very handy when he added an alarm to his garage as well years later when we also had cable satellite dish(es) added. Don't forget to leave a piece of string in the line to pull additional lines later on.

20-06-2012, 11:34 PM	#9
SP59 Partially Addicted to C2E Join Date: Jan 2012 Location: Sherwood park	That link from Epcor seems to be for service from the street to a property vs. service from say a residence to a detached garage.