poke holes in my electrical plan please

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poke holes in my electrical plan please - mound - 09-21-2021

I had another thread specifically about two 220v circuits in conduit.. I think that ran its course, so now I'll start this thread for my complete plan.

For those of you electrician types that want to play along and sanity check my amateur efforts, here's what I've come up with for my shop (garage) wiring.
(I've had to link to externally hosted images as WoodNet isn't letting me attach anything for some reason)

[Image: vHh5Sky.png]

Basically the plan is to create a 3/4" EMT raceway up near the ceiling with 6 drop-points.

Each gray box numbered 1-6 is a 4x4x2 box. The thicker black lines labeled A-F are the 3/4" EMT and the thinner unlabeled black lines are 1/2" EMT for the drops.

Anything "below" the boxes on the diagram is on the wall, anything above is on the ceiling.

Each non-gray color represents an individual circuit.

The purple/blue are a pair of "general purpose" 110/20 circuits. This pair of circuits will go the entire run and drops are to a 2-gang box with both a black and white receptacle indicating which is which.

One light circuit can be tapped off any box, but I'll tap it in 3 spots for layout reasons (it's a busy ceiling with large I-Beams in the way). I've only included one light circuit as the shop (garage) itself already has a light circuit fed from the house.

One 220/20 circuit (green) powers both the table saw and jointer.

The 110/20 dust collector gets its own (yellow) as does the 110/20 air-cleaner (red) and the 220/30 heater (orange)

All 20amp circuits fed with 12g THHN , the 30amp heater fed with 10g THHN , and the dedicated ground wire inside the whole EMT run will be 10g green THHN. (though I will do some more research into using the EMT itself for grounding as was suggested in the old thread.)

I labeled each conduit section (A-F) and each box (1-6) so that I could try to put together a matrix of how many of each size wire is passing through or splicing at each point so I could do fill calculations and check for needed ampacity adjustments using these online tools:

Conduit Fill Calculator (https://www.southwire.com/calculator-conduit)
Box Fill Calculator (https://www.constructionmonkey.com/calculations/electrical/boxfill)
Ampacity Calculator (https://www.cerrowire.com/products/resources/tables-calculators/ampacity-calculator/)

I think I counted everything right and came up with this matrix which shows how many of each sized grounded and non-grounded conductors are inside each section of conduit or inside (spliced/passing through) each box. This is what I came up with, and it looks like I can use a 4 11/16" sq. X 2 1/8" box (42 square inches) as that's well above the minimum box volume for each spot and none of the fill percentages exceeded 40%. I also didn't find any need to adjust wire sizes for ampacity (again, sanity check me please!)

Diagram of drop-points (1-6) and conduit sections (A-F):

[Image: 134Dy3a.png]

edit: where the 220v tablesaw/jointer are, I'll put them before the general purpose pair of 110's so that their conductors don't need to pass through. The drawing makes it look like they'd be after in the wire feed.

edit2: Brainstorming a simpler idea that may be much more flexible.. Rather than "calling out" specifically the air cleaner & dust collector since I know I want them to be able to run at the same time as other things, if I instead just make 3 "generic" individual 110v circuits and two "generic" 220v circuits, then just run them all to each location, so that no matter where I am, I have close access to any of them in any combination.. If one thing's for sure it's that my layout is going to evolve over time.. What would that look like, a 4-gang box holding 3 110v receptacles and 1 240v receptacle?

thanks for any comments!

RE: poke holes in my electrical plan please - ajkoontz - 09-21-2021

I'm not an electrician by any stretch but I wanted to comment that I like the outlet drops in the ceiling idea. Not as elaborate as your plan, but I put a bunch of outlets in my garage (shop) ceiling and would recommend this to anyone on the fence about putting outlets in the ceiling.

RE: poke holes in my electrical plan please - mound - 09-21-2021

(09-21-2021, 01:26 PM)ajkoontz Wrote: I'm not an electrician by any stretch but I wanted to comment that I like the outlet drops in the ceiling idea. Not as elaborate as your plan, but I put a bunch of outlets in my garage (shop) ceiling and would recommend this to anyone on the fence about putting outlets in the ceiling.

Yah it's nice to be able to plug something in directly overhead rather than trying to drape extension cords somewhere.

RE: poke holes in my electrical plan please - MstrCarpenter - 09-21-2021

What would that look like, a 4-gang box holding 3 110v receptacles and 1 240v receptacle?

I'm not sure that how it looks is important. I can tell you that the cover plate is going to be tough to find. I think I would do a 4"x4" with two duplex (three circuits) connected with a short piece of EMT to another 4"x4" for the 240v would be easier to source parts. I'm not the person to check box fill requirements but I think you're pushing it with one box.

Also, I think the price difference for 1" EMT is less than the additional effort required when you have to install another circuit.

RE: poke holes in my electrical plan please - mound - 09-22-2021

(09-21-2021, 10:08 PM)MstrCarpenter Wrote: What would that look like, a 4-gang box holding 3 110v receptacles and 1 240v receptacle?

I'm not sure that how it looks is important. I can tell you that the cover plate is going to be tough to find. I think I would do a 4"x4" with two duplex (three circuits) connected with a short piece of EMT to another 4"x4" for the 240v would be easier to source parts. I'm not the person to check box fill requirements but I think you're pushing it with one box.

Also, I think the price difference for 1" EMT is less than the additional effort required when you have to install another circuit.

Sorry wasn't using "look like" in an aesthetic sense, more of a "what enclosure would I get to put them all side by side"
I think you're right, put the 220 and 110 in their own boxes separated by a horizontal length of conduit.

So you're thinking, despite 3/4" fitting it all, go with 1" anyway just for expansion? Sounds good to me.

RE: poke holes in my electrical plan please - TDKPE - 09-22-2021

(09-21-2021, 10:08 PM)MstrCarpenter Wrote: I think I would do a 4"x4" with two duplex (three circuits) connected with a short piece of EMT to another 4"x4" for the 240v would be easier to source parts.

That's what I did, all around the shop walls.  Some boxes have two duplex outlets, others only a single, but I can easily add another to those with singles if I need to.  Keeps box fill down and avoids needing a box extender.  I also only have one 120V circuit around the perimeter, but my shop is very small, and a cord from a utility bench receptacle which is on a different 20A circuit is no big deal since it's only a few feet away.  And I often plug small tools like sanders into a ceiling light receptacle, as there are a couple of empty ones up there and the ceiling is very low (basement).[attachment=37804]

RE: poke holes in my electrical plan please - srv52761 - 09-22-2021

(09-22-2021, 07:40 AM)TDKPE Wrote: That's what I did, all around the shop walls.  Some boxes have two duplex outlets, others only a single, but I can easily add another to those with singles if I need to.  Keeps box fill down and avoids needing a box extender.  I also only have one 120V circuit around the perimeter, but my shop is very small, and a cord from a utility bench receptacle which is on a different 20A circuit is no big deal since it's only a few feet away.  And I often plug small tools like sanders into a ceiling light receptacle, as there are a couple of empty ones up there and the ceiling is very low (basement).

The covers on tdkpe boxes are approved for grounding your devices if you decide to go that route.  Notice the corners where the covers contact the box have been flattened, and the devices are attached to the cover in at least two points.  That middle screw on the 120v outlet is redundant, or can be a one screw attachment if you are running a separate equipment ground anyway; but filling it makes for a more professional looking install.  Always looks tacky to leave screw holes empty. Included with the cover is usually some serrated nuts, as the device is to be semi-permanent to the cover.  They also add about 8- cubic inches to your box volume. To save some time, they make a box to box fitting. [attachment=37805]

RE: poke holes in my electrical plan please - mound - 09-22-2021

Thank you both.

So TDKPE's setup could allow for the EMT itself to act as ground.. But I think he said he prefers a dedicated ground wire, so presumably his devices being in contact with the approved covers with the flat corners, is itself redundant?

Still up in the air about using the EMT as ground vs. including a wire.. If a dedicated #10 equipment ground wire were included, and in each drop-point it splices out to the next things in line (say, 3 directions, up to the ceiling, down the wall and donwstream to the next drop), that's four #10 ground wires "entering the box" (even though some are "entering" and some are "exiting" in my mind) so does that count as "4 #10 splices" in the box fill calculator? or is the ground treated differently and counted just once? (is it a "space" thing or a "heat" thing?)

I like those covers that add volume! Covers like that (without any openings) would be nice on the 4x4 drop points I think if I get close on box-fill

edit: If the box fill calculation is about heat dissipation, how to "calculate for" the volume needed for wire nuts where things are spliced? How can I know how many wire nuts I can fit to support the splices that otherwise the box fill calculator says is ok?

RE: poke holes in my electrical plan please - TDKPE - 09-22-2021

<blockquote>
But I think he said he prefers a dedicated ground wire

. . . </blockquote>That comes from a lifetime of being in places where the conduit and wiring gets beat up and nobody does anything about it.  Break the continuity, and you can have an open ground.  These are buildings put up during WWI for steel fabrication, boiler making, etc., and some of the surface wiring in there, which admittedly is newer than that but still old, takes a beating for decades, often with devices hanging out of them, and bent and broken conduit and joints.  That's where why hesitation comes from, though that would never happen in my own shop or yours.

RE: poke holes in my electrical plan please - mound - 09-22-2021

(09-22-2021, 11:42 AM)TDKPE Wrote: <blockquote>
But I think he said he prefers a dedicated ground wire

. . . </blockquote>That comes from a lifetime of being in places where the conduit and wiring gets beat up and nobody does anything about it.  Break the continuity, and you can have an open ground.  These are buildings put up during WWI for steel fabrication, boiler making, etc., and some of the surface wiring in there, which admittedly is newer than that but still old, takes a beating for decades, often with devices hanging out of them, and bent and broken conduit and joints.  That's where why hesitation comes from, though that would never happen in my own shop or yours.

Gotcha.. Does your setup you showed a picture of include a ground wire?