Electrical Sub-Panel

[wh500special 2,262]

Man, I've been a posting juggernaut lately...

 

I have some questions for the electricians among us about installing a subpanel in my basement.

 

I want to install a 60-amp subpanel in my basement so I can run my tablesaw, dust collector, lathe, etc and not be dragging a bunch of individual circuits back to the other end of the house to the main panel.  My combined loads aren't that big, and I've decided that a 60A availability at the 240V sub will offer plenty of headroom for anything I might ever conceivably need.

 

I already own a 100A load center that matches the 200A main panel in my house.  I presume if I protect this 100A panel with a 60A breaker in the main that everything is fine.  The 100A main breaker in the sub panel would then just be a big on-off switch should I ever want to kill power to the rest of the circuits. 

 

Question 1:  Is it OK to mix and match like this? 

 

The run from my main panel including the up and down needed to reach the planned location for the sub is about 30' (+/-).  6-ga THHN in a conduit is probably what I'd use, but just looking for a sanity check on that sizing.

 

Question 2:  Is 6-gauge wire the right size to feed a 60A panel?

 

PVC conduit isn't something I've ever used, but it sure looks convenient.  I can use metal, but my bending skills aren't very good and I'm likely to generate some significant scrap in "oops" production as I try to steer around the HVAC unit that blocks my straight shot to the main panel.

 

Question 3 and 4:  Is PVC okay to use INSIDE the building?  I'll be hanging whatever conduit I pick from the bottom of my joists thru a storage area.

 

Grounding has me confused a bit.  I know that you cannot bond the ground and neutral in the subpanel.  No problem there.  But I'm seeing here and there on the net that a new requirement for driving a ground rod at a sub panel is in play.  And, should the ground conductor in the conduit be insulated or can it be bare.  I assume insulated.

 

Questions 5, 6, and 7:  Do I need to drive another ground rod?  And, does the ground wire in the conduit back to the main panel need to be insulated?  Should that ground also be a 6-ga or should it be lighter?

 

If I drive a ground rod, I have no interest in going through my basement floor so I don't have a leak path.  I'd like to avoid the new ground rod if possible.

 

Question 8:  Can these go anywhere, like thru a wall or something? 

 

Thanks in advance,

Steve

[JimD 3,347]

I've been out of the electrical contacting business since 2000, but I can tell you what we were doing then here in Ohio. Either up the breaker feeding your sub to 100 amps and the conductors to #2, or exchange the 100 amp breaker in the sub for a 60 amp breaker. It is not advisable to feed a main breaker in a sub with a breaker of lesser value. In fact, it would be advisable to install a main lug panel instead of a main beaker panel so there is only one main in the line. 6 gauge is the proper size for 60 amps, and pvc conduit is ok to use in the house. Do not bond the neutral conductor in the sub. The ground conductor can be bare, and a ground rod would not be required. If it is determined that a ground rod is needed I would drive the rod outside the house and run a #4 bare ground from the ground bar in the sub to the rod, exiting the house through the outside wall.

 

Keep in mind there have been four national electrical code revisions since 2000. I'm sure some more current advice will be coming shortly.

[Sparky-(Admin) 23,106]

I've been out of the electrical contracting field for about 3 years here in Connecticut but everything Jim said is good and correct advise.

Mike.............

[CRE1992 135]

I work for my Uncle's electrical company when I not at college. Everything he said seems good. Since you are in your basement, it does not need a grounding rod. If it was in another structure such as a detached garage or shed, you would.

 

If you basement is unfinished, you could always run SER they sell it in 6 wire by me at the local electrical warehouse. Just make sure to use the correct fittings and mount the sub panel securely. Typically to a piece of plywood that is painted black and bolted or tapconed to the wall.

Edited February 20, 2013 by CRE1992

[KC9KAS 4,744]

I think all the above info is correct.

I would tell you to look at the most up-to-date National Electrical Code, but reading code just about requires a Philadelphia Laywer.

[wh500special 2,262]

Thanks guys for the replies thus far.  I knew there were some electrical guys on this forum that have had to sift through the code, so figured I'd exploit your wisdom for my gain.

 

I'm not lazy, but reading through the code just wasn't as simple as I'd hoped.  And I have a better-than-basic knowledge of how to wire things, but making stuff follow the NEC always requires advice.

 

I hadn't considered using the bundles SER cables mostly because I fear someday someone else in my household might hang something on the wire bundle or compromise it in some other way.  And with a 60+ amp breaker "protecting" the bundle, I figure it would take an aweful lot of energy to blow open.

 

I've never used plastic conduit for anything other than outside work.  I didn't know if there would be restrictions inside since to me the codes aren't always elementary or intuitive.  It sure is cheap stuff, that's for sure.

 

i went ahead yesterday and mounted the box to the wall.  Other than some knockouts I removed for the wires being fed by the box, I haven't poked any big holes out yet, so can still do about anything to connect it to the main service.  Since I move at a glacial pace, it will probably be a few weeks before I bring power to the box.  So I still have time to think about things.

 

I have wired in a lot of stuff at work over the years, mostly 3-phase but don't need to do much at home.  Even simple hook ups seem to take forever for me.  I'm always amazed by you guys who do these things for a living at how fast and efficiently you can work.  While I'm still standing there trying to figure out what size wire to use, you've already run conduit and pulled wires.  While I'm staring at the diagram on a transformer trying to decide what terminals to use, you're doing final cleanup.  When I'm trying to strip the jacket off a SOW cord, you're already on to the next project.

 

I've always figured if I had to do it over again and pick a trade, it would probably be electrician.

 

Thanks for the help!

 

I'll be asking again hopefully this spring when Dad and I finally pipe power down the hill to his barn.

 

Steve