Electrical questions on using conduit

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Hello,
I'd like to add some receptacles in my unfinished basement for using the space as a workshop, and my understanding is that I need to use conduit. I'm comfortable wiring circuits using NMB cable, but this will be my first time using conduit, so I have several questions.
1) My default idea is to use EMT, but there seems to be a confusing number of different types of raceways. Can anyone point me to a good overview of them?
2) My understanding is that is acceptable to use EMT as the equipment ground, but is it still a good idea to run a separate EGC? If I do so, I assume that I should bond every box to the EGC. Does it matter if the EGC is bare or green?
3) The wall is concrete for the first 4' and then a wood stud cripple wall covered in 1/2" sheer paneling. I don't have any experience fastening to concrete, what is the best way to go? It would be easier to attach to the sheer paneling, but I expect 4.5' is too high to be convenient for receptacles.
4) I'd like to run two 120V circuits. What are the pros and cons of having them share a neutral versus having separate neutrals? One appealing option is to use two duplex receptacles in each box, each fed from a different leg. I believe this requires a double pole breaker?
Thanks, Wayne
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I believe I've figured this one out--since the circuit will require GFCI protection, using a shared neutral would require an expensive 240V/120V GFCI breaker. So to use 120V GFCIs, I'll have to use separate neutrals.
Cheers, Wayne
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Wayne Whitney wrote:

You would not necessarily *have to* use separate neutrals. You could use separate GFCI's.
Bob
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Wayne Whitney wrote:

True. Here's why: Because you are in a basement, you'll need GFCIs. This means either a GFCI breaker (big $$$), or an outlet GFCI. But you want two circuits. This either means you get a 2-pole GFCI breaker (about $100), and then you can run a single neutral, or you use two outlet GFCIs. But if you use two outlet GFCIs, you can not merge the neutrals back together again.
In our case, we were forced to wire with a single neutral, because I wanted to use plugstrips (made by Wiremold), and those have a single neutral and two hots. So we were forced to use the $100 2-pole GFCI breaker. Compared to the other costs of finishing the whole basement, and building the woodshop, the cost of the breaker is insignificant.

Yes, but you can only use the separate neutral until you get to the first GFCI in the daisy-chain. After the GFCI (that is, on the load side of the GFCI), you can't merge the neutrals back together. If you try, the GFCIs will trip all the time. So the suggestion of a single neutral with cheap outlet-style GFCIs only works if you never use the load side of the GFCIs. And if you want to have lots of outlets, the GFCIs will add up.
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_firstname_@lr_dot_los-gatos_dot_ca.us wrote:

OK. But if you have a separate GFCI receptacle for every receptacle, i.e. you never you the LOAD screws on the GFCI receptacles, then you could get away with a shared neutral? Of course, all those GFCI receptacles quickly add up to the cost of a GFCI breaker.
Cheers, Wayne
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Wayne Whitney wrote:

Actually, you can use the LOAD terminals, but it can get confusing pretty fast so it's not necessarily a good idea -- you can't have a shared neutral on the LOAD side of any device. I can think of a good example where you might want to do this. Lets say you want two new 20A 120V circuits in your garage, and your garage is 100 feet from your breaker box. To reduce the voltage drop when you're operating 2 heavy loads at once, run 12-3 cable to the first double-gang outlet box and install 2 GFCI outlets. Run half the outlets in the garage from the load side of one GFCI and the other half from the load of the other GFCI. You have to run separate neutral wires from this point on.
Bob
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Completely agree. Oh, and in addition, you might want to run 10-3 cable to feed the garage (copper is expensive, but still cheaper than the aggravation of having an annoyingly substandard electrical system, for the next 30 years).
As an example: A few circuits in the my basement shop are being run with 8-3 cable, even though they are just 220V 30A circuits. It's just that for the largest power users (the table saw I want to buy eventually), I want to have spare capacity and no voltage losses.
Our basement will have three 110V outlet circuits. One feeds most of the rooms except the shop. It goes from the panel to a GFCI outlet right next to the panel, and from there on only to regular outlets (one long daisy chain, so there is no confusion). The other two come off a 2-pole GFCI breaker (mucho bucks), and feed a 2-circuit Wiremold plugmold strip that covers most of the walls in the shop, all wired with 12-3 cable.
I just hope that the various building inspectors agree with our opinions.
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There's one other factor I haven't seen mentioned in this thread. As I understand it, you're only allowed to share a neutral between two circuits that are on different phases.
Greg Guarino
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...

Let's see. One extra roll of 12-gauge THHN at Home Despot: $5.
For 8 of the 10 outlets you install, use a $7 GFCI instead of a $1 outlet (you need the first two GFCIs anyhow).
You do the math (you are in the math department after all, I'm just a physicist who is already burned out and trying to prevent getting himself electrically fried in addition).
By the way, given your location, I recommend that you do your parts shopping at the Lowe's in Union City, or at Orchard Supply. They seem to be much better organized than the Home Depot's around the Bay Area. Matter-of-fact, today I gave up on a trip to the Capitol Expressway Home Depot, because half the stuff I needed couldn't be found, and the checkout line for the only register that was open wrapped halfway around the building. I'll drive to Gilroy or Union City for Lowe's instead, get the stuff at OSH (more $$$ but less chaos), or frequent the local hardware store.
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Doug Miller wrote:

It can if you do it right. It won't work if you need a GFCI protected 240V device. Otherwise, you can even mix 240V unprotected outlets and 120V GFCI outlets and 120V-outlets-connected-to-the-GFCI-load-screws, all on one edison circuit. (it may not meet local codes to mix 120V and 240V outlets on a branch circuit, but that's not the point.)
As long as the only return path for the hot LOAD wire of a GFCI is back to the neutral LOAD screw of the same device, it will work. The GFCI will not even know it is sharing a neutral LINE wire.
Bob
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This is Turtle.
Reply below ----- I only run EMT on HVAC systems and a electricians here maybe able to answer better.

I think you confussing me here now. I only know of 2 types of races ways. 1) Indy 500 Race Way 2) Electrical Race way. A Race Way is a shelf made for wires or conduit, covered electric route for wires , or a bunch of wires in conduit run together to be neat and look good. I really only know one type of race way as far as you looking up the conduit verses the wires to put in it or the rating of the wire. Now you can have the wires out of coduit or in conduit in a race way but you just rate the wire in free air or in conduit and the race ways it just the holder for the conduit or the wire.
Just rate and figure everything in EMT and forget the race way thought.

In a residentiual job like your. The Ground can be green or the Nake ground can be used. I don't know of any requirement to tie the ground to the EMT but let the EMT be it's own grounds. I don't know about using the EMT as the ground but in commercial it is a NO NO. I don't think I would do that.

Get you a box of Wall Ackor set and drill hole in concrete with the bit supplied with it and put in a wall ankor and the clamp it with a screw [ supplied with the kit ] to put a EMT wall clamp to hold the EMT. This is not a big deal at all and a wall ankor kits cost about $6.00 for a 100 Ankors, 100 screws, and one drill bit for concrete. You can put the EMT where ever you want with the kit and conduit.

Your making a mountain out of a mole hill here.
Everything [ receptical wise ] that is tied to 1 -- single 120 volt service breaker can share the Hot , Neutral, and ground.
You don't need a double pole breaker for anything here.

Now you have left out here the most important thing of all. What are you wanting to run or plug into these receptical and what will be the amp draw of them? Do you want 2 circuits with 2 breakers or all on one circuit ? You head of the game here by doing the wiring and have no ideal of what it will need as wire or conduit needed. Alway tell or know what you want to supply with power before running power to it and then finmd out you don't have the circuit big enough to supply the load. Let us know what you want to power up before wiring begins.
TURTLE
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OK, I guess I used the wrong term, I meant to say "different types of conduits". Sounds like EMT with THHN wire is the way to go, I was just curious about the alternatives.

Yes, that's true, I was trying to get a handle on EMT before I got to the details. Thanks for the responses.
Here my situation: the main loads will be a table saw (15 amp 120V universal motor), planer (15 amp 120V universal motor), dust collector (8 amp 240V induction motor) and jointer (6 amp 240V induction motor). [BTW, both the DC and jointer claim to 1 HP. Is the jointer motor really 25% more efficient?] There will also be a 120V air compressor and miscellaneous portable tools.
I was planning on 1 240V 20 amp circuit and 2 120V 20 amp circuits, because other than the dust collector, I'll mostly be using these tools one at a time. I'm happy to have the jointer next to the dust collector, so they can share a duplex receptacle. My planned physical layout is this, along a 20' wall:
Quad 120    Quad 120    Quad 120    Electrical Panel         Duplex 240
My preference would be for each quad 120 to be two duplexes on separate circuits. I'm a little confused about running multiple circuits in the same conduit. Namely:
Are there any rules that if multiple circuits are in the same conduit or box, they have to be shut off by the same breaker? Is there anything special about having a wire run through a box without being tapped?
If I run 2 separate 120V circuits in one conduit, do I end up with two white wires and two black wires? Or am I supposed to use different colors for each wire?
If I run all three circuits in one conduit, then that's 6 conductors plus ground. Do I have to derate the conductors, and does that mean using #10 gauge THHN for a 20 amp circuit?
Thanks, Wayne
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One of these days, you will go to a good tool store (I suggest CB tool in San Jose, but the place in Alameda isn't half bad either). You will come home with a 3HP Unisaw, General or Powermatic in your truck. At that point, you'll need a 240V 30A circuit. And you'll be kicking yourself for not providing one.
Suggestion: Wire the 240V outlets with 10-3 cable. It is quite a pain to wire with, but will save your sanity in the long run. You can continue to use a 20A breaker and 20A outlets, just use heavier wire as insurance for the future. As mentioned before, I went further overboard, and used 8-3, which is quite a pain to use (I'm dreaming of a General 650 with a 5HP motor).

No. Just run it through. Technically, there is no need to leave extra slack. If the box isn't very crowded, I like to make a loop in wires that just run through; so far I've never needed to use that loop, so this is probably a waste of time.

Yes, you get two blacks and two whites. This is a bit confusing, so I like to use a Sharpie and put red or green or blue marking on the wire, at the ends. Or make a flag with white electrical tape, and write a description on it. This is not code necessary. I've seen one industrial installation being done by professionals, and they didn't bother marking any of the wires (takes too much time). On the other hand, they installed everything right the first time, they had wire tracing tools to identify the ends, and they don't tinker endlessly with their installation. YMMV.
For the hot conductors, you could buy red (and blue and mauve and ...) wire. Unfortunately, for the neutral conductors, you have to use something that is mostly white. In principle, white wire with a colored stripe exists, but I've never seen it for sale (other than in industrial quantities).

Yes, you have to derate the conductors. I just went down to the building site in the basement (also known as the desaster area), and got the NEC. Article 310, table 310-19, note 8: You have to derate to 80% for 4-6 current-carrying conductors, and to 70% for 7-9. But, don't despair: The allowable ampacity of 12 gauge THHN wire is either 25A or 30A (depending on whether the things you attach at the end of the wire are rated to 60 degrees or 90 degrees C). And 80% of 25A is 20A, so you can continue to use 12 gauge wire. If you have 7-9 conductors, I find the code confusing (not clear whether the 70% rule applies to the 90 degree rating, because the conductors have been separated by the time they are attached to 60 degree rated things like breakers and outlets).
And you don't count the grounding conductor, and you maybe don't count the neutral conductor (note 10 to the same table says that it doesn't need to be counted, but only if the neutral carries only the unbalanced current, and there are no nonlinear loads, so I wouldn't chance it).
By the way, with 6 conductors plus ground (of which some might end up being 10 gauge), I would go to 3/4" conduit. 1/2" conduit would probably be legal (it can technically handle nine 12-gauge conductors), but installing it would be a royal pain. And nearly all outlet boxes have both 1/2" and 3/4" knockouts, so it is easy.
And: Finding a copy of the NEC (could be slightly outdated version) at a used bookstore is an excellent idea.
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Theres no reason to identify the neutral conductors, these all attach to the same bussbar in the breaker panel anyways.
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IIRC, the OP mentioned he would only be running 2 outlets, with one or perhaps two neutrals.
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_firstname_@lr_dot_los-gatos_dot_ca.us wrote:

What's the place in Alameda?

OK, if I use 3/4" EMT and have 6 #12 THHN conductors plus ground in it, and I want to pull out two #12 conductors and replace them with #10 or #8, how hard would that be? My entire conduit run is a straight 15 feet, it should be a relatively simple install (once I figure out all the nuances of conduit).
You're point is a good one, I just need to balance it against my expectation that I would move out of the basement before buying any hefty equipment.

Thanks very much!
Cheers, Wayne
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The Japan Woodworker, 1731 Clement Ave, Alameda. Specializes in Japanese hand tools (I'm beginning to salivite just thinking about them), but also has a good selection of big machines.

Through 15 feet of straight conduit: trivial. Even if there are other conductors already in place. Probably don't even need a fish tape, just push the wire through (maybe get a piece of solid wire to use as a fish, then use it to pull stranded wire through). If you had said "50 feet of 1/2" conduit, with 3 ninety-degree bends, already stuffed", I would have said: Hard but doable (you'll have skinned knuckles afterwards).
Our worst experience with this was pulling three 2/0 conductors (about 1/2" of copper each, for a 200A service) through about 70 feet of 1 1/2" conduit, with a few bends. We ended up with one person pushing like mad, and filling the conduit with wire pulling lubricant, and the second person using their full 200 lbs weight as a gravity operated human winch. Took all afternoon, and afterwards all our hands were a big mess. It is very hard to hold on to wire that has been smeared with lubricant, so you keep sliding off, and hitting the sharp metal edges. Much fun. Should have used 2 inch conduit instead.
Good luck!
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Emt is the easiest and most efficient way to go.

No. The only time a breaker has to be common tripped with another is when the 2 circuits are connected to the same device YOKE.
IOW - a 220v receptacle is on one yoke. It's breaker must have a common trip.
A duplex receptacle split into 2 circuits by removing the jumper tab would be considered 2 circuits on one yoke, and the breakers would have to common trip.
A combination device at your back door, with 2 switches on it both on the same yoke, one fed by one circuit for the back door light and the other for the power to your backyard shed which is on it's own circuit, would have to be common trip.

Nope just pass it through.

In residential both hots can be black, but you could use a black for one circuit and a red or blur for the other if you desire.
You will have 2 neutrals and they must be white.

No.

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