Load Center for "new" shop

[John K Jordan]

Now - I have peace of mind, will have plenty of headroom, and my voltage drop will be under 2%.

We're on the same wavelength! I did the calculations for my shop and sized the copper for a voltage drop just over 1%. They laughed at me for going "oversize" according to some, but I'm happy. My run is about 250', underground in conduit. Fortunately, I was able to do all the dirt and electrical work myself. I also buried ethernet cable in another conduit and ran a spare 2" conduit, empty except for a rope inside. Who knows.... A few months ago I had a 650' aluminum direct burial line suddenly fail so I replaced it with copper in conduit with 60 amp breakers, way more capacity than I need - it will feed a planned equipment shed with modest electrical requirements - lights, air compressor. small welder.

JKJ

[Tom Bender]

John's comment on drawings is important. If you are not working on drawings it's time to start. List the circuit number on each box on the drawing and on the finished box cover.

[Kevin Goss]

Keep in mind, you could go with a square d Homeline panel, and many allow for "tandem" breakers, such as this item # from home depot # H2448M100PVPSG . it's a 24 space panel that allows for 48 circuits. It comes with a few standard breakers and then you can add the tandem breakers which cost just slightly more than regular space breakers, but unlike the high priced 2-20 amp tandem breakers like many are used to with regular QO panels, Homeline sells single pole outter breakers with a 2 pole inner breaker as well. It's pretty nice stuff and doesn't cost much.

if you want to use the conduit as a ground I would recommend using set screw couplings. I just see way too many compression fittings come lose. but as long as they are installed well and the conduit is supported very well it shouldn't be an issue. But in my own place i'd just do 4 circuits per 3/4 conduit and pull 1 ground in each conduit to be assured. a spool of 500' #12 ground is less than $50. For myself i would buy the load center at a big box store and the fittings and wire at a electrical supply house. but i'd send the supply house your full order and ask for a quote and compare. sometimes it's a huge difference. in the last year our supply house conduit for 3/4 has gone up to about $7 /stick when it's $4.50 /stick at lowes. so shop around

[John Pariseau]

Keep in mind, you could go with a square d Homeline panel, and many allow for "tandem" breakers, such as this item # from home depot # H2448M100PVPSG . it's a 24 space panel that allows for 48 circuits. It comes with a few standard breakers and then you can add the tandem breakers which cost just slightly more than regular space breakers, but unlike the high priced 2-20 amp tandem breakers like many are used to with regular QO panels, Homeline sells single pole outter breakers with a 2 pole inner breaker as well. It's pretty nice stuff and doesn't cost much.

if you want to use the conduit as a ground I would recommend using set screw couplings. I just see way too many compression fittings come lose. but as long as they are installed well and the conduit is supported very well it shouldn't be an issue. But in my own place i'd just do 4 circuits per 3/4 conduit and pull 1 ground in each conduit to be assured. a spool of 500' #12 ground is less than $50. For myself i would buy the load center at a big box store and the fittings and wire at a electrical supply house. but i'd send the supply house your full order and ask for a quote and compare. sometimes it's a huge difference. in the last year our supply house conduit for 3/4 has gone up to about $7 /stick when it's $4.50 /stick at lowes. so shop around

I'll look into those breakers, and will pull a dedicated ground wire. I like the look of the compression fittings, less "busy" visually, but will ensure I tighten them well. Watching online EMT videos the installer all warn to tighten well - and that people usually don't tighten them enough.

As for wire/conduit - thanks for the tip. I've found the local Mc-Mc to have the best wire prices around, their conduit is a bit more expensive than the big box stores but they offer free delivery.

[Bobby Robbinett]

I second the notion for getting a SquareD homeline load center. I just bought one myself in the 100amp 20/40 configuration. I can get double pole 20a and 30a breakers locally at Lowe’s for under $10ea and 15a single pole breakers for under $5ea. That is a bargain! I bought this to use as a sub panel in my shop. It feeds off the main panel in my shop with #1 aluminum wire and works great. I would suggest giving some thought to using Mc cable instead of the typical yellow stuff and conduit. I am doing the new lines in my shop with 12/2mc which has the conduit sort of built in for lack of a better term. I am going to use steel outlet boxes with the Mc lines attached with what ever fittings are appropriate. I will use 1/2” pipe hangers to secure the 12/2mc around to various locations in my shop. Very easy to install and saves a bit of time and money on conduit and such.

[John Pariseau]

Load center arrived! I'm not ready to mount it, but am getting close and trying to evaluate my options.

This is where I brought up the electrical through the foundation - 2 - 2", 1 - 3", 1 - 1"?

3" is for my main power
2" for an outlet on the outside
2" for network cable (fiber or otherwise)
1"? for my ground wire

Do I just use 3/4" ply behind the load center or should I use plywood plus a fire resistant material like durock/drywall? I have some durrock left over, but if it's overkill I'll just mount a piece of plywood.

[Jim Becker]

The load center can mount directly to the plywood.

[Frank Pratt]

Put insulation behind the backer board to prevent condensation in the back of the panel during cold weather. The local AHJ may require it.

[John Pariseau]

Put insulation behind the backer board to prevent condensation in the back of the panel during cold weather. The local AHJ may require it.

So... I have R20 in the walls, intend to heat in the winter (probably not this year anymore, COVID kinda messed up my plans) - would this change things?

[Jim Becker]

So... I have R20 in the walls, intend to heat in the winter (probably not this year anymore, COVID kinda messed up my plans) - would this change things?

I would think that if the wall is insulated, then you're good to go. The photo up above in post 21 doesn't show any evidence of insulation...

[John Pariseau]

I would think that if the wall is insulated, then you're good to go. The photo up above in post 21 doesn't show any evidence of insulation...

Yeah... I did what some call "wrap and strap" - insulation on the outside. Not very common, more or less a homemade SIP.

[John Pariseau]

If I could get some advice on one more thing, would appreciate it. The middle tube is for my main conductors - it is 3". I oversized this tube - I only need a 1-1/4" dia pipe.

The load center has up to a 2-1/4" diameter punchout.

Basically, what should I do:

1) buy a PVC 3" to 1-1/4" reducer, then use a 1-1/4" PVC threaded offset to attached it to the load center

or

2) cut off most of the pipe, buy a PVC 3" to threaded 1-1/4" reducer, and run rigid up to the load center, with a rigid 1-1/4" offset

I'd prefer #2 - I don't like the idea of the conductors in a potentially flammable tube, but perhaps I'm overthinking things (again). Would there be any code implications with this, since I'd be mixing conduit materials?

[Jim Becker]

I'd take that 3" conduit right to the panel in the size it is to preserve the space capability and use the 2.25" punch-out with appropriate fittings to get it connected. Dropping the diameter to 1.25" down and away from the panel puts a potential bottleneck/challenge for pulling due to friction, etc. IMHO.

[Ron Selzer]

you are not allowed by code to reduce the size of the conduit until it terminates. You can terminate it where it is in a junction box and then come out of the junction box to your panel with a different size conduit, in your case the 1 1/4" you want to use as long as it is big enough for the conductors in it. The junction box cover must be accessible when done. You can put an access panel in a finished wall for accessibility.
Your wire would pull straight thru the junction box with no breaks to the electric panel
good luck
Ron

pvc electrical conduit is good all the way to the panel, unless it is located where it is subject to physical damage, then it needs some type of protection installed. IF metal conduit is installed to the panel, then it needs to be bonded to the panel, not hard to do, just one additional thing to do.

[Paul F Franklin]

Or enlarge the hole in the panel to take the connector for the 3" pipe. The knock-outs are a convenience; but you are not limited to using only the provided knock-outs. A greenlee punch is the easiest tool to use for this, but a jig saw with a metal cutting blade would do in a pinch.