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Project Offgrid - Garage Build, Part 2

In the last part, most of the trench work was buried back up and the GridBoss and FlexBoss21 were mounted on the wall. This post picks up where that left off — getting the remaining panels mounted, running EMT, terminating cable, and getting temporary power back into the garage so I can actually finish the job.

Garage Progress

Here is the original drawing —

Fusion 360 mockup of the garage wall with all four enclosures, conduit and panels laid out

And here is where the last post left off:

Garage wall after Part 1 — only the FlexBoss21 and GridBoss were mounted on the strut

Its time to get the other panels mounted, and get cable pulled.

Mounting Panels

Step 1 — acquire new panels.

New 200A main load center and the smaller 125A critical-loads subpanel staged on the floor

The left panel is an Eaton BR 200A outdoor 60-circuit load center with plug-on neutral.

Eaton BRP30B200RV25

The smaller panel on the right is the old critical-loads panel from my original solar project. It is a 12-slot, 125A outdoor-rated panel.

Mounting Main Panel

Looking at the main panel, it already had holes for screws.

Back of the 200A main panel showing the factory mounting holes

But they were slightly too small for the mounting hardware I was using.

Mounting bolt held next to a factory mounting hole, clearly too large to pass through

A quick pass with a step bit fixes that issue.

Cordless drill with a step bit enlarging the panel's mounting holes

Afterwards, I needed to mount the bottom. BUT, there aren't any holes intersecting with my existing unistrut. Shame.

Main panel hung from the top strut with no factory holes aligned to the lower strut rail

With a bit of help from the drill, I landed a few perfectly spaced holes.

Freshly drilled hole through the panel back, aligned with the lower strut rail

And now you can do pull-ups on this panel with absolutely zero concerns of it coming off of the wall. Seriously, I did.

Main panel fully mounted to the strut wall with the deadfront installed

Do make sure to remove the bonding screw...... unless this is intended to be your bonding location.

Close-up of the green bonding screw and the BR-style "bonding screw - when required" warning label

Mounting Subpanel

For the subpanel, I used the existing two holes near the top.

Then drilled a single hole in roughly the middle to mount the bottom. I added a washer to make sure there wouldn't be any issues with the screw pulling through.

Subpanel mounted with a washer at the lower screw point

And of course, I did verify I can successfully use the panel as gym equipment.

Per my drawing, spacing is exactly 1ft between all panels.

Tape measure between the main panel and subpanel showing exactly 12\" of spacing

With that, all of the panels are now mounted.

Connecting Garage Power

Ok, remember that part where I ran a trench through my garage's power line? Well, I need power in my garage to run tools, welders, etc. So before running all of the conduit, it is time to get power connected up in the garage.

New panel in shed

The panel in the shed was destroyed a bit after the trencher forcefully pulled the cable out.

Old shed subpanel with the feeder ripped out the bottom, case bent

Step 1 — disconnect everything.

Shed subpanel with all the branch circuits disconnected and pulled to the side

I found a small pipe fitting helps to release these locking MC connectors.

Small pipe coupling used as a tool to depress the locking tab on an MC cable connector

Out with the old panel.

Empty wall spot where the old shed subpanel used to live

Comparing with the new panel (left).

Old subpanel next to the new larger panel on the shop floor for size comparison

Mount the new panel. Use screws to secure.

New shed panel mounted to the wall with the new 2/2/2/4 feeder coming up through the bottom

Bend the 2/2/2/4 to fit.

2/2/2/4 feeder bent into a service loop inside the new shed panel

Start opening knockouts and installing connectors.

Hand pulling an MC whip through a new knockout in the shed panel

Wire everything up.

Shed panel with all branch circuits re-terminated on the bus

Wiring up the GridBoss

Since the 2/2/2/4 cable has already been pulled into the GridBoss, I just need to terminate it.

Open GridBoss with the feeder cables draped through, ready to be landed

I will be using the #1 smart port for my shop's electrical connection since it is rated for a 125A breaker. The #2 port is rated for 90A, and #3 and #4 are only rated for 60A.

After a bit of work, the shop feeder was terminated.

Inside the GridBoss with all of the Eaton breakers in place and the shop feeder landed on smart port #1

A 100A breaker is used for the time being.

For the time being, I used a temporary connection back to a 60A breaker on the existing panel. (Ignore the conduit — that is in the next section.)

Wider view of the GridBoss with the temporary feeder run over to the existing house panel

And.... let there be light. I can charge my Milwaukee batteries again!

Nighttime shot of the shop with all the lights on — power restored

Back to working on the garage.

Running Conduit

Time to start the fun part — installing conduit!

Wide shot of the garage wall with the first sweeps installed and conduit roughed in below each panel

I started by installing the 90-degree sweeps in the main locations.

Then I cut the first piece of conduit. I trimmed a few inches off of the elbow to get it perfectly level.

Torpedo level resting on top of the first cut piece of EMT, showing it dead level

Torpedo level across both runs of EMT confirming both are level and parallel

Then I did the same with the conduit between the main panel and GridBoss.

Conduit run between the main panel and GridBoss installed and squared up

Starting to look a little bit better, eh?

View of all three lower conduit runs in place, looking much cleaner

I needed a few short pieces of unistrut for securing the conduit to the wall. I used my Dewalt chopsaw for the task.

Dewalt abrasive chopsaw cutting short sections of unistrut on the driveway

And — the installed mounting brackets for the conduit, back to the unistrut.

Garage wall with all of the conduit secured to the wall via short strut sections and pipe clamps

Between GridBoss and FlexBoss

Since the FlexBoss was mounted slightly higher than the GridBoss, this made the process slightly more challenging to run nice, pretty conduit. After looking at the options, I decided to run the main conduit in through the rear.

I used a 45-degree PVC elbow just to vet the idea.

45-degree PVC elbow held in place between the GridBoss and FlexBoss as a sanity check on the routing

PVC 45 mocked up in the actual run between the GridBoss and FlexBoss21

Then I measured to cut the real conduit.

Tape measure stretched between the GridBoss and FlexBoss to size the EMT cut

I used my pipe bender to put a SLIGHT angle on the new conduit.

Hand pipe bender on a section of EMT, putting a shallow offset bend in it

Which lined up nearly perfectly.

Slightly-bent EMT held in position between the two enclosures, aligned with both hubs

Afterwards I installed the connectors and tightened everything down.

Finished EMT run between the GridBoss and FlexBoss with compression connectors installed

Pulling Cable

Cable Used

With all of the panels connected, it was time to start pulling some cable.

For the subpanel, which is behind a 100A breaker, I went with 2 AWG copper THHN, which is rated for 115A. I also used this cable for wiring the inverter.

Coils of 2 AWG red/white/black copper THHN and green ground wire laid out on the shop floor

I ordered around 45 feet total (red, white & black).

Nassau - 2 AWG Copper THHN/THWN-2

Note — not affiliated with Nassau.

For the 200A main panel, I ordered 25ft of 4/0-4/0-2/0-4 feeder cable.

Nassau - 4/0-4/0-2/0-4 Aluminum Mobile Home Feeder Cable

While I vastly prefer using copper, aluminum saves a good chunk of money here.

Pulling Cable

For the most part, pulling the cable was not too bad. I used cable lube to make this job quite a bit easier.

Quart bottle of Gardner Super Slick cable pulling lubricant held in front of the open main panel

Amazon - Gardner Super-Slick Cable Lube1

After putting a good amount of lube into the conduit, even the massive 4/0 cable pulled pretty easily.

4/0 aluminum mobile-home feeder cable pulled through the conduit into the main panel

Aluminum conductors — use anti-oxidant

Since the 4/0 feeder is aluminum, the terminations need anti-oxidant compound (Noalox / Penetrox / equivalent) on the conductor strands before torquing them into the lugs. Bare aluminum oxidizes the moment it hits air, and that oxide layer is a resistor — the connection heats up, the lug loosens, and eventually you get a fire.

The fun part is getting the cable bent into place. That is a workout.

4/0 cable bent and dressed into the main panel terminations

While my pipe cutter doesn't work the best for cutting pipe, it works extremely well for cutting through this thick cable.

Ratcheting PVC pipe cutter being used to cleanly cut a section of 4/0 cable

After getting mostly everything bent into place for the main panel and subpanel, it looked like this:

Main panel and subpanel both wired up, feeders dressed and landed on the buses

Info

Ignore the temporary circuit running to the subpanel — its powering the mini-split here in my office, since the old panel is out of room.

It will be cleaned up and done correctly soon enough.

I found a short section of PVC pipe and a big wrench helps to bend the cable better.

For the GridBoss side, the wiring is nearly completed. The only items left to do in here are to disconnect the incoming main power and move the conduit to instead run into the GridBoss, and to run ethernet/communications cables.

For the FlexBoss21, I pulled the cable through the rear. Don't forget to add an EGC!

FlexBoss21 opened up with the red/white/black 2 AWG conductors pulled in from below, stripped and ready to land

FlexBoss21 with the 2 AWG THHN feeder pulled in through the rear knockout and landed on the input lugs

When used with the GridBoss, nothing should be connected to the load port.

Info

Notice, nothing is connected to the non-backup loads port.

My intention is to be able to run FULLY off-grid if desired. The non-backup port is ONLY active with either a grid or generator connection.

That is not desired for this installation.

Originally, I planned on using the subpanel as a "more critical" loads panel. Instead, I am now planning to use it as a load-shedding panel — when power is out and batteries start to run low, the GridBoss can switch off the entire panel to save energy.

You may also notice the small 1" conduit running out the bottom of the FlexBoss21, going to the GridBoss. This is for low-voltage communications cables.

Finishing Exterior Conduit

Almost forgot to add this section!

When we left off from the last part, the exterior of the house looked... roughly like this:

Exterior wall by the mini-split with only the original 1.5" EMT run to the shop in place

I went ahead and ran 1" conduit for the PV wiring, to the right of the existing 1.5" conduit for the shed power wire.

1" PV conduit added to the right of the existing 1.5" shop feeder conduit

For the rest of the cables, after kicking around a few ideas, I decided to toss it all into a piece of 2" conduit hanging low on the wall.

All of the exterior conduit roughed in along the stone wall — PV, shop feeder, and the new low 2" run for comms/etc

After drilling the hole, I attached a pipe connector and screwed it down tight, with lots of silicone to prevent water from seeping inside the house.

Close-up of the 2" PVC fitting tucked tight against the wall, sealed with silicone

And, voila, a piece of conduit. Just need to cement everything together now.

A few hours later....

All done! And the hole has been mostly covered back up.

Exterior at dusk — finished conduit run along the wall, ground rod and old disconnected conduit removed

While the image is dark, you may notice there are a few things missing. The grounding rod which was previously installed here was not used at all — the main grounding connector for my house is at the pole.

So I removed this one. I also found the conduit running down the side of the house was disconnected and not in use, so I removed that as well.

For the interior side, nothing special here.

Interior side of the wall showing the incoming feeders landed on the existing panel

I came out the next day, added some sand, and placed a big rock in the middle to help clean this area up a bit.

Tidied-up exterior with fresh sand and a large flat rock placed beneath the conduit run

This area is very close to being done — there is still more work to do here in the future. I need to add an exterior rapid-shutdown switch, AND redo/re-route the existing incoming power cable into the GridBoss.

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