Installing a Generator Transfer Switch, Part 3: Wiring in the main

Almost there...

In order for this panel to act as a sub-panel, it has to get power from the main panel.  Because I ordered the TRC0603C, where the 06 means it has a 60amp breaker coming in from the main, I also had to install a 60 amp breaker in my main panel.  This also means I had to adequately size the wire from the main breaker to the sub-panel...

The feed wire...

According to the National Electric Code (NEC from here on out) 2008 Handbook, 6 ga wire should be large enough to handle the 30amps of current.  I went to Lowes and looked at their wire current and pricing page, which said it was only good for 55amps... after speaking with the sales associate there, they referred to a page copied from the NEC and agreed that I was safe.  My electrician here at work agreed with me, especially since I'm only going 6ft.  These guys also agree with my decision... hmm, they have a good bit of good articles!  I suggest you check it out.

The end of the wire...

Wiring it up...

With my wire ready to go, I first had to pick the cable clamp size I thought would work best for the wire I was working with.  I didn't find any great guides for choosing a size, but I decided to go with 3/4" clamps.  Next I had to remove the knock out in the sub-panel and the main panel.   

I highly recommend you turn off the main breaker before you remove the cover or  do any work in your main panel!  This will ensure you ALMOST can't electrocute yourself.  (Same thing applies once the sub-panel is hooked up).  Always check to make sure the wires or equipment you are working with are not energized! 

The main panel with the cover removed.  Seriously, don't touch the stuff circled in red, it can still shock you!

NOTE: If you want to wire in the sub-panel first, you can work with the main panel still energized... that way you can still turn on the lights to see what you are doing.  But remember, this is assuming you are not in the main panel, your generator is not feeding the sub-panel and the feed wire has not been hooked up to the main panel yet!

NOTE: Always kill the breaker feeding your feed wire to the sub-panel and unplug your generator before thinking about working on the sub-panel!

With the knock-out's removed and the cable clamps installed, I next had to feed the wire into the panel to get an estimate on how much I'll need to strip back the insulation.  Hint: Leave yourself a few extra inches!  Stripping the insulation works the same as it did when I wrote Installing a Generator Transfer Switch, Part 2: The Generator Feed Wire.  I like to use a Sharpie marker to mark the location on the insulation to strip it back to.

The TRC0603C Sub-panel.  EDIT: Those are POWER meters, not current.

REVIEW: Red and Black wires go to the breaker.  White goes to Neutral and the bare copper wire goes to ground.


With the main insulation stripped back, I put the wire back through the cable clamp and tightened it down.  From there, I routed the wire through the sub-panel to get an idea of how long each wire needed to be.  Trim all the wires to whatever length you desire and then trim the insulation back about an inch.  Give the bare wires a nice coating of the ox-guard (corrosion inhibitor) and clamp them down.

NOTE: In this instance, I clamped the Neutral (White) wire down using the main lug.  In the picture above, on the left hand neutral bar at the bottom is a hex nut.  I backed this out, put the wire in, and torqued the nut down.

The line-power feeding into the breaker, coming in from the bottom

You can see above that the red and black lines go to the breaker while the bare copper wire goes to the ground.  I already mentioned white going to neutral.  Also shown is the first circuit being run.  This one is going up to a terminal box where I'm splicing in a wire that isn't quite long enough to make the switch from the main panel to the new sub-panel.

But you can also see for this new circuit that black goes to the breaker, the white goes to the neutral bar and the bare copper wire goes to ground, just like in the main panel.  This is repeated for each circuit being wired.

Making progress...

One thing that I did, that I thought was a good idea, is use some wire labels I pulled out of the trash while working at a previous employer.  They would print labels and if the printer screwed up, they'd trash the whole batch.  Some of them never got printed... so I'm using a permanent marker to label my circuits and heat shrink the labels onto the wires.  This way if I ever need to go back and figure things out, it should be easier to do!

Heat shrinking a wire label... it's hard to do AND take a picture!

Everything was going along just great until I ran into some wires coming down from upstairs... they wouldn't reach my new box.  So after two trips to the hardware store, I ended up installing two junction boxes to fit all of my wire junctions inside, seen below.

The first junction box

These boxes are necessary any time you need to splice two wires together.  In this case, the upstairs bathrooms and bedrooms wouldn't reach in addition to a few from the main level, so there were a few splices to make.

Be sure to use the correct size wire nuts!

I learned a few things about junctions after I finished this up.  You don't need wire nuts on the ground wires... just take all of the ground wires and leave about 5inches extra length and twist them all together.  That could possibly save some money.  I also learned you can put as many wire splices into a box as you can safely fit... so don't splice off too much shielding, you want them inside the wire nut so they don't short out to another wire when you pack them in there like sardines!  You can read my previously article on splicing wires here: How to strip/splice wire.

The final product

THE INSPECTION...

So there you have it, the inspector came last night.  I passed my inspection with flying colors!

The only issue was that I had previously made a knee-jerk decision to use different wiring after everything was up and running and when the electrician came, he helped me put it back to how it had been done previously.  Everything worked awesome and now we are ready for A storm.

Notice I did not say "THE STORM"!

I don't think "THE STORM" will ever come, but little by little, day after day, eventually there will be a storm.  Now I'm a little bit more prepared for when a storm hits. 

Can you "Sleep when the wind blows"? (That was the first place I fount it posted, cant remember where I first heard it.)