poke holes in my electrical plan please
#21
Yes it does, but box and conduit fill aren't an issue. There's only the one 20A 240V circuit plus one 20A 120V circuit in there, with no sharing of conductors other than the EGC.
Tom

“This place smells like that odd combination of flop sweat, hopelessness, aaaand feet"
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#22
(09-22-2021, 01:13 PM)TDKPE Wrote: Yes it does, but box and conduit fill aren't an issue.  There's only the one 20A 240V circuit plus one 20A 120V circuit in there, with no sharing of conductors other than the EGC.

Thanks!

I've been looking through the Grainger catalog.. 
Should I go with all galvanized steel for the garage shop?  they also have steel (not galvanized) and galvanized zinc.
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#23
(09-22-2021, 09:21 AM)mound Wrote: 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?
In most box fill tables and calculations, all grounds are counted as one conductor, the largest one. Almost all common devices are counted as two conductors. If you connect , say, three conductors and add a short piece to supply a receptacle, that wire with both ends within the box is not counted. If you mount a fixture that has pigtails for connections, they don't count either if they're smaller than 16ga., but there is mention of a "domed base" in the NEC. Wire-nuts, lock-nuts, and bushings on your connectors don't count either. However; if the connector or clamp is inside the box, that counts as one conductor based on the largest conductor in the box. (In your application, I don't think it applies.) There has been discussion on how far EMT can span without support. More specifically, is if a "support" is needed if it's only 6" long, and/or does it need to be "secured". Just to make it really confusing the NEC has an exception for "fastening". Bottom line. Do the best you can to follow the code, neat and professional looking, (yes, appearance counts with electrical) and be nice to the Electrical Inspector.
Sign at N.E. Vocational School Cabinetmaking Shop 1976, "Free knowledge given daily... Bring your own container"
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#24
(09-23-2021, 09:42 PM)MstrCarpenter Wrote: In most box fill tables and calculations, all grounds are counted as one conductor, the largest one. Almost all common devices are counted as two conductors. If you connect , say, three conductors and add a short piece to supply a receptacle, that wire with both ends within the box is not counted. If you mount a fixture that has pigtails for connections, they don't count either if they're smaller than 16ga., but there is mention of a "domed base" in the NEC. Wire-nuts, lock-nuts, and bushings on your connectors don't count either. However; if the connector or clamp is inside the box, that counts as one conductor based on the largest conductor in the box. (In your application, I don't think it applies.) There has been discussion on how far EMT can span without support. More specifically, is if a "support" is needed if it's only 6" long, and/or does it need to be "secured". Just to make it really confusing the NEC has an exception for "fastening". Bottom line. Do the best you can to follow the code, neat and professional looking, (yes, appearance counts with electrical) and be nice to the Electrical Inspector.

Thanks! This volume calculation makes more sense when I think of it in terms of heat rather than occupied space. 

side question, I've got some parts on hand, a couple of those 4-11/16 square x2-1/8 (the larger size) boxes for the upper raceway, and was hoping to drop 1/2" EMT from them to supply the wall mounted outlets. 

It seems all of the knockout tabs on that box are too big for the 1/2" conduit fittings... am I missing something?


edit: also, to the box fill calculation, just to clarify.. say there is a 120v circuit running through the box (2 conductors).. That circuit is split to proceed down the line, as well as up and down.. So one circuit entering, and splitting three ways. Does that count as 8 splices?
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#25
<p>Use conduit reducing washers to change from a 3/4" to 1/2" ,&nbsp; one inside of box and one outside of box. &nbsp; <a href="https://www.homedepot.com/p/Halex-3-4-in-x-1-2-in-Rigid-Conduit-Reducing-Washers-4-Pack-26820/100177505">Link </a>&nbsp;&nbsp; Roly<br></p>
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#26
(09-24-2021, 09:05 AM)Roly Wrote: <p>Use conduit reducing washers to change from a 3/4" to 1/2" ,&nbsp; one inside of box and one outside of box. &nbsp; <a href="https://www.homedepot.com/p/Halex-3-4-in-x-1-2-in-Rigid-Conduit-Reducing-Washers-4-Pack-26820/100177505">Link </a>&nbsp;&nbsp; Roly<br></p>

Perfect. thanks!
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#27
(09-22-2021, 08:26 AM)srv52761 Wrote: The covers on tdkpe&nbsp;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.

I've got all my parts gathered and laid out on a big table to organize the install.   All the boxes and covers I got look like the ones TDKPE showed earlier and you wrote about.  I started asking myself, well if I'm using a dedicated ground wire, that means I should use it "across the board" as if the whole system were being done in PVC and plastic. Right? That would mean bonding the ground wire to the box, and the box to the green screw on each receptacle (or is that overkill?)... With #10 wire..  As I started thinking about all that extra wire and wasted space and time, in this otherwise sea of metal tightly connected to each other, I'm thinking maybe you're right that in my home shop where the connections won't be falling apart, abused and ignored, if NEC says an all metal system is a good ground, I should trust that.

If I go that way, there would be literally no green or bare ground wire anywhere in the system?

Which brings me to a comment you made in the older thread;

(09-20-2021, 01:04 PM)srv52761 Wrote: Don't be so quick to dispatch the idea of using the conduit as your ground.  Do some more research.  Mike Holt's forum is well respected among electricians, engineers, and inspectors.  Studies have demonstrated conduit, including EMT,  sized appropriately for the conductors as a ground is superior to copper wire.

How does one determine if the EMT is "sized appropriately for the conductors" ?   All but one of my circuits are 20amp (#12 conductors), one is 30amp (#10 conductors) and I was going to use 3/4" EMT for the raceway and 1/2" EMT for the drops.  Is this sized appropriately?

Thanks!
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#28
<p>
(09-24-2021, 06:48 AM)mound Wrote: edit: also, to the box fill calculation, just to clarify.. say there is a 120v circuit running through the box (2 conductors).. That circuit is split to proceed down the line, as well as up and down.. So one circuit entering, and splitting three ways. Does that count as 8 splices?
<br></p><p>If I'm picturing what you're describing, you're splicing off a running or pass-through circuit to add a drop.&nbsp; That's 6 conductors entering the box.&nbsp; It would only count as two conductors if there was no splice, but since it's cut and spliced to a drop, it's six.&nbsp; 12 gauge counts as 2.25 cubic inches, so that's 13.5 ci not counting devices, internal clamps (none if using EMT), and an EGC which is only counted once.<br></p>
Tom

“This place smells like that odd combination of flop sweat, hopelessness, aaaand feet"
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#29
(09-24-2021, 10:48 AM)TDKPE Wrote: If I'm picturing what you're describing, you're splicing off a running or pass-through circuit to add a drop.
That's 6 conductors entering the box. It would only count as two conductors if there was no splice, but since it's cut and spliced to a drop, it's six. 12 gauge counts as 2.25 cubic inches, so that's 13.5 ci not counting devices, internal clamps (none if using EMT), and an EGC which is only counted once.</p>

Yes you're picturing what I'm describing correctly, except it's 2 "drops" at each point, not 1. (one down the wall, the other up and across the ceiling) - so that makes it 8 splices, not 6, correct?
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#30
Basically I'm hoping to achieve a raceway with "drops" like this in series:

   

I'm probably suffering from analysis paralyses over "splice count".

Each color is its own circuit, all are using #12 solid. 
 
If I assign 2 splices to each circuit, that's 12 splices.  But those are for going up and down.  I have to also splice in to keep going right. Does that add in 12 more splices?
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