Tag Archives: greenfield cable

2014/08/24 (N) The Critical Path

The current “critical path” on the garage/HVAC project is the east wall of the garage which has to be finished before Darryll returns.  Although not as pressing as the drywall work, our first task after breakfast was to (finally) connect the separate ground wire from the garage sub-panel to the house main electrical panel and remove the bonding screw that tied the grounds and neutrals together in the sub-panel.  That took about an hour, but that was because it was work that had to be done carefully as the main panel was energized while I was working on it.

With the ground wire taken care of we sanded drywall compound on the east garage wall.  We wiped the dust off with a slightly damp sponge and I applied the next coat of drywall compound.

We then worked on wiring.  I finally decided on the locations for the two furnace switches, each of which had to be within three feet of their respective units.  I decided to locate the switch for the library HVAC unit on the new wall opposite (20″) and above (16″) the cable entry hole in the side of the furnace.  The switch will be in an outdoor rated surface mount junction box with the supply cable entering from the rear.  I had already run the cable into the middle wall cavity and had to drill a hole through one of the studs to get the cable where I needed it to be.

I decided to locate the on/off switch for the ceiling mounted garage furnace on the ceiling about a foot to the right of the right rear corner, again using an outdoor rated surface mount junction box.  The dedicated 15A cable was already routed to that general area so we just had to move it to the new location.

We also had to install the wiring for the thermostats.  Darryll brought a large reel of 4-conductor, 18 AWG thermostat cable, so we had the material we needed.  I was studying the installation instructions for the thermostats and it appeared that they needed 24 VAC to operate.  I called Darryll and left a message regarding this.  He called back fairly quickly and told me we did not need transformers as they were already in each of the furnaces.  He also left me know he would be back on Wednesday morning.

With the transformer question answered we were able to proceed with the cable installation.  The thermostat for the garage furnace will mount on the outside of the west wall of the new utility closet, so we had to run thermostat wire from that location through the attic to the ceiling mounted switch box.  The thermostat for the library HVAC unit will mount on the wall to the right of the door into the garage and above the return air register/duct, so we also had to run thermostat wire from there through the garage attic and over to the location of the on/off switch in the utility closet.  I worked in the attic while Linda worked in the garage.

We took a break for lunch and then started installing insulation in the utility closet walls.  We got one staple installed and discovered that we were out of staples.  That meant a trip to Lowe’s.  Lowes’s is about six miles driving distance and we prefer not to go for just one small thing, so we made a list.  The Arrow staple gun takes T50 staples.  The surface mount junction boxes have several threaded holes into which you can screw different clamps depending on how the cable is connected.  I planned to use flexible armored cable, sometimes referred to as “greenfield”, to bring 120VAC power to the furnaces.  Lowe’s had 6′ lengths of armored cable with an extra foot of wire on each end.  I needed a little more than 36″ for the library furnace and a little less than 36″ for the garage furnace, so that worked out nicely.  The guy in the electrical department got me set up with the right clamps for the ends called saddle connectors.

When I got home, I discovered that I had bought brads rather than staples, so Linda headed back to Lowe’s to return the brads and buy the staples.  While she was gone I pulled the wires out of the armored cable and cut the armor into two pieces.  I fed the wires back through the shorter piece and connected it between the garage furnace and the switch box.  Linda got back before I could complete the cable for the other furnace, so I set it aside to finish later.

With a good supply of staples we insulated the west wall of the utility closet and the space above the door on the south wall.  We then installed drywall over those same areas.  We had to notch around the flue pipe and the black iron gas pipe, but we measured carefully (and twice) and the panel fit just right.  We applied fiberglass tape to the one vertical seam, and prepared a length of corner bead for the outside corner at the junction of the two walls.  Linda prepared dinner while I applied joint compound to the seam and screw dimples.  I mudded the corner, pressed the corner bead in place, and then mudded over it lightly.  I then did some touch up sanding on the east garage wall and applied what I hoped would be a final coat of drywall compound.

I finished just in time to clean up and have dinner; vegan Pad Thai made from scratch.  A small glass of the 2009 Egri Merlot and some lemon melon later for dessert put a nice cap on a very productive day.