Electrical questions on using conduit

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This is Turtle.
Reply below and try to sort it out.

This is a bit of over kill here but your not paying for labor so go for it.
Now the wires run for the jointer & dust collector. i would just run one set of wires for the 230 volt service wire to the two of them and have a receptical for each. Both can share the wire / breaker as they both will be connected very near each other. Wire size / breaker size will have to be dealt with other than this talk.
Now the table saw and the planner in my opinion should have their own seperate service of 120 volts and have each a breaker by theirself. Planner one set of wires and breaker and a set of wires just for the table saw's 120 volt service.
You will have 2 service sets of wires for the table saw and Planner. Then one set of wires / breaker for the DC and Jointer with 2 recepticals. You will have 2 black wires / 1 green or nake ground wire to be joined at the 2 receptical. We have not cover wire size yet.

NO and NO
Now tring to figure out what set of wires go to each of the 120 volt services or equipment. you can paint one set of wires for one of the pieces of equipment with spray paint about 1 foot at the end to tell which is which. Now really it will not make much difference for your only going to have 2 blacks / 2 whites and 2 ground wires. The two whites and the ground at the switch box are going at the same place and then one black wire to each of the equipment. It don't take much to figure it out for there is only 3 wire for each and different colors to boot. Just get one black to each piece of equipment and the white & Ground to the receptical. To each piece of equipment you will have ground/common/ Black.

You will have 2 black wire , 2 white wires, and 2 Green or Nake ground wires. Then 1 Black [hot wire]/ 1 white [common ] / 1 Green or nake [ground wire ] will go to one piece of equipment and the other set left will go to the other. DON'T FORGET TO HAVE A GROUND WIRE TO EACH. It can be green or Nake wire.

We will have to cover the rating of the wire / breaker size by the way you run it and go by a wire chart for what you call derating the circuit or wire. I have wire charts to tell you what will fit in the conduit and what rating of the number of wire / amp draw of each / size of conduit. Tell me what way your going to run the wire like all in one or seperate conduits. If you like you can e-mail me and I can look up the wire rating verses the conduit size for you or post back here.
TURTLE
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maybe
I have started using that liquidtite flex conduit with the grey pvc outer jacket in a lot of places.
Still prefer the EMT type for the longer straight runs and that, but then I put inna handy box here and there and drop or go around a corner with the flex..........
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SVL



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The best overview of what you CAN LEGALLY do is the NEC itself. It is not exactly written for easy reading. Combine that with a good electrical supplies catalog (for example the Grainger catalog), to show you what is available and the costs of things, and you'll figure it out.
Note: I didn't suggest buying everything at Grainger ... just to use their catalog as a reference guide. Nothing wrong with Grainger, but the local Borg is cheaper.
In practice, there is only one option: EMT. The stronger conduits (IMC and rigid) are much harder to use, may require threading of the ends, and don't give you any real advantage (unless you intend to drive vehicles into the walls). The grey plastic conduits, which are glued, are quite brittle and will not survive long in something like a shop. And they are actually more expensive and more work to install than EMT; their advantage is that they are waterproof, but who cares. Blue smurf-tube (officially known as ENT, or Electric Nonmetallic Tubing) is so wimpy, you wouldn't catch me dead running AC power through it; plus I don't think its up to code for exposed work anyhow. It is suitable for low-voltage (computer and phone wiring) in non-exposed locations, and that's about it.
OK, I lied. There is a second option, but it is a little weird: Wiremold and some competitors make squarish raceways, that is usually clipped together out of a base (that you screw onto the wall) and a cover. You have to then use the matching outlet boxes. Advantages: A more finished look. And you can get the surface raceway prewired and pre-assembled with electrical outlets. Disadvantages: The smaller models have very little room for wire; the bigger ones look very bulky. EMT has a more industrial look; the surface-mount raceway always has the look of "retrofit in cheap construction" to it. EMT is probably strong (will sustain less cosmetic damage occasionally being hit when you swing a sheet of plywood around in the room). You can get a huge variety of EMT fittings and boxes for it at any hardware store, while only electrical distributors and mail-order have a good selection of fittings for surface-mount raceways. And the wiremold stuff is quite pricy (all these little $2 and $4 items add up quickly).

Would you trust your life to sheetmetal? Even worse, would you trust your life to using iron (that rusts!) as a conductor?
Here's my policy: I always run a separate ground conductor for outlet circuits; not necessarily for lighting circuits (where there is very little chance of touching energized circuits). This is overkill from a NEC and code point of view, but I like it.
You need to eventually bond every box and every bit of metal conduit to the ground conductor. But they don't all need to be bonded directly to the copper grounding conductor. I like to always bond the boxes that are reachable, with a dedicated ground pigtail (not by using the metal-to-metal contact from the outlet strap). Also, if a grounding conductor runs through a box, it is easy to loop it around the grounding screw once, so many boxes get grounded for free. But for boxes that are not normally reachable (like the one at the top of the conduit, out of reach), and the conduit itself, I'm happy to rely on the metal-to-metal contact of box to conduit for grounding (as long as a significant fraction of the boxes are bonded). None of this dedicated grounding is required by code (AFAIK), but it makes me feel better.
If you are pulling dedicated wire (typically THHN), it is actually easier to pull green insulated wire - it seems to slide better. I only use bare copper conductors if the wire in the conduit is the long stripped end of a Romex (NM-B) cable. Also, I always worry about having uninsulated wires in outlet boxes. What if they get bent wrong, and touch the exposed hot or neutral screw at the side of an outlet? This could cause hard-to-debug intermittent shorts or ground faults. I'm nervous enough as it is when using NM-B, so I try to avoid it when using conduit.

Actually, I've been told that in a shop area, it is convenient to have outlets relatively high (above the benches and worktables). So I have planned a continuous ring of Wiremold plugstrips along the wall at 4' height. The 220V outlets (for bigger machinery) and a few extra 110V outlets are at the usual 16" height. Other people, other styles, and other usage patterns might have different opinions.
Here is another question: If you can hide all your wiring in the stud wall (above 4' height), then you probably don't need conduit at all. As far as I know, the only reason conduit is typically required in a basement is that you can't run NM-B in exposed locations, and basements are typically concrete or block walls, which forces you into exposed wiring. This might save you lots of work.
Lastly, how to attach things to concrete: This is really easy: Make holes in the concrete, and use plastic anchor. The problem is that in practice this is hard and expensive. First, it is a tad hard to get really good plastic anchors in the US. The typical red conical ones are quite wimpy and unreliable. I like using the "Fischer" brand grey plastic anchors from Germany, which are considerable stronger and more reliable, but those you'll have to get mailed to you by friends in Germany (or oder them from Amazon.de, and pay horrendous shipping charges). And then you'll have to get the matching metric drill bits. Second problem is how to make all the little holes (typically 1/4" or 5/16" holes for plastic anchors. The easy but comfortable solution is to buy a pneumatic drill hammer; they are made by Bosch, Milwaukee, Hitachi and so on, and start at about $200. They always have SDS or spline attachments for the drill bits. The nasty but cheap option is to buy a hammer drill, which uses a normal chuck. Drilling holes with a hammer drill is very annoying (it rattles your arm, and makes terrible noises). Using masonry bits in a non-hammer drill is a non-starter; with lots of patience you can make a hole or two, but it is pointless for mass production.
Good luck! We're in the middle of our basement finishing project. Fortunately, because we are adding a lot of stud walls, nearly all the wiring is NM-B inside the walls.
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Thanks for the lengthy response! A couple comments:
_firstname_@lr_dot_los-gatos_dot_ca.us wrote:

Good point.

I was under the impression that it is not OK to make a connection between a screw and a wire by wrapping the wire around it like that. Perhaps I am mistaken, or there is an exception for the EGC?

Thanks for the tip. BTW, when would I want to use something other than THHN?

OK, I lied a bit. The concrete wall in question starts off at 62" high and steps down to 56". I am planning to put my outlets at 48" high, so that forces me to anchor into the concrete.
Now, at the top of the concrete wall, there is a 3.5" ledge, then 1/2" plywood shear panels I recently installed, then an insulated cripple stud wall. I didn't want to put anything in the cripple wall as I expect the shear panels should be not be cut. I could fir out the cripple wall and run NM-B horizontally at a height of 72", say, and then drop down to metal boxes at 48" high with conduit stubs. Is that any easier than a single horizontal conduit run at 48" high? I would imagine it wouldn't be.
Cheers, Wayne
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Tell me more about that. If that's really true, I'll have to redo a lot of boxes before the building inspector shows up. I'll check into it.

Inside conduit, in practice, never. The only single-conductor wire that is commonly sold is THHN. And the wire inside NM-B is also de-facto THHN (even though it is not labeled such, it has to be rated to 90 degrees). Clearly, extension cords, outdoor underground feeders, and machine tools are a different story.

Looks like more work to me: You have to build all the furring or soffit to hide then NM-B in, then you have to cut and connect all the conduit stubs, and you still have to worry about getting the NM-B in and out of the conduit (easiest way is to put a small handy-box there). You would end up with way more pieces, and need more wire.
By the way, several posters mentioned Tapcon screws. I've used them for things like hanging shelving. But when I pulled my permit, the chief inspector (Santa Cruz county) said that even though the Tapcons are rated for structural use, and have ICBO evaluation reports, the building inspectors hate seeing them, because the tend to wiggle loose if you hit them a few times, or if something connected to them vibrates. So I have avoided them where it matters - just to avoid trouble with the inspector, and switched to plastic anchors (for non-structural things, like electrical boxes and plumbing) and steel anchors (for all structural stuff). This might be a general statement, or it might just be one inspectors pet peeve, don't know.
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_firstname_@lr_dot_los-gatos_dot_ca.us wrote:

Well, I am far from an authority, so don't take my word on it, but I would be curious to know what you find out. I think what I had read was not to loop conductors around a screw terminal on a device (receptacle, switch, and so on). But even if that's true, looping the EGC around a ground screw may be fine.
Cheers, Wayne
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EMT is probably superior, but your inspector will probably not require it. My shop has NMD along the bottom of joists, plus short stubs of PVC to the outlet boxes. All surface mounted.
The NMD along the bottom of joists is acceptable because there's lathe there protecting it (for later installation of drywall on the ceiling).

Don't rely on the EMT for equipment ground. The NEC apparently permits it in residential, but our codes forbid it. Green or bare.

It wasn't in my shop.

I did this slightly different. I sent over three shared neutral four wire circuits. Each supplies two outlet boxes, each box has one duplex (but split) receptacle. No circuit supplies two adjacent boxes. A total of 12 outlets, each 120V circuit supplies only two, not on the same box.
Oodles of power. Six circuits tho ;-) No GFCI. I'd have to use dual GFCIs here.
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I've only used EMT, and only 1/2" at that. It's reasonably easy to work with, but as with anything else, there's a learning curve. In fact, it's the "curves" that require the "learning".
I've seen installations where people used elbows and offset couplers instead of bending the pipe. In fact, I had to run wire through such an installation once. It was a real pain in the neck to thread the wire through. You have to open each elbow in the run.
A conduit bender lets you form nice smooth curves, once you get the hang of it. For me the hardest part was learning to get the offset bend (a small "jog" in the conduit that brings it a little away from the wall as it goes into a box) to face in the correct direction. Buy more conduit than you need to account for errors.
You'll also need a rattail file small enough to smooth out the inside edge of the conduit pieces. Otherwise the wire insulation can be damaged by the sharp edge.
Other people on this thread have suggested running larger wire for possible future needs. That may be a good idea, but you should probably get yourself a good book or other reference to let you know how many of what gage wire are permissible in the size conduit you choose. Or, preferably, how to choose the right size for the wires you intend to install.

I think that electricians tend to use Tapcon screws. They are probably a little less work than the plastic anchors I usually use.
Greg Guarino
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EMT and surface mount boxes.

I use green, except in large (#6 or larger) gauges. EGC isn't required, but is a good idea.

Tapcon screws. If you plan on doing a bunch of fastening of things, a hammer drill makes short work of it. If you get a box of 100 Tapcon fasteners, they come with the drill bit.
You'll be able to attach other stuff to the concrete walls with this as well.

You've come across the reasons. I'll suggest stranded wire, as it is easier to work with, and prevents the usage of el-cheapo back wired outlets.
Since you can buy wire by the foot at the borg, I suggest color coding the wires, different colors for each circuit.
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On Tue, 21 Sep 2004 18:03:18 -0700, Wayne Whitney wrote

Wayne,
If NM is allowed as a wiring method in your jurisdiction, then it can generally be used for exposed work in an unfinished residential basement, but not where it could be subject to damage. You can protect it with running boards, or sleeve it in conduit as necessary. However, for a workshop, IMHO, you're wise to consider another wiring method. It will make for a safer and more workman-like installation. In answer to your questions
1) In addition to EMT, the common raceway types are Rigid, Intermediate Metal Conduit (IMC), Rigid Non-Metallic Conduit (NMC), Flexible Metal Conduit (FMC or Flex), Armored Cable (AC) and Metal-Clad Cable (MC).
Rigid and IMC are heavywall aluminum or steel pipe used in various hazardous locations or where subject to extreme damage. They are difficult to bend and install and are over-kill for your proposed application.
NMC is a gray PVC pipe available in Schedule 40 or Schedule 80 wall thickness. It is joined by solvent cement and is relatively easy to install. It must be fastened within 3' of each box and every 10' otherwise. There is an assorment of boxes and fittings available in PVC which solvent weld to the pipe, or you can use conventional metal boxes and attach the pipe with a male threaded adaptor and lockring. NMC obviously does not provide a grounding path.
Flex is made of an interlocking spiral of aluminum or steel strip. It is relatively easy to install but difficult to fish. It must be fastened within 12" of each box and every 4 1/2' feet, but for a neat installation it is usually supported at much closer intervals. It provides a grounding path if the conduit and fittings are listed for grounding, otherwise it may only be used as the EGC where the ground return path does not exceed 6'.
AC and MC look like flex but come as an assembly with conductors installed. They are available with different conductor combinations: 14-2, 14-3, 12-2, 12-3 are commonly available. AC does not include a grounding conductor, instead it has an internal bonding strip which is folded back and clamped in each fitting to assure the ground path. MC includes an insulated grounding conductor. Both types provide a grounding path. AC must be supported like Flex but MC may be supported at 6' intervals. AC must have plastic "anti-short" bushings installed in the cut ends where they attach to a clamp or fitting.
I personally like using EMT, but installing it can be tedious. Bending becomes easy after 10 years of practice, but initially there's a lot of wasted pipe. You probably should consider NMC or MC as your wiring method.
For two circuits of #12 THHN conductors, 1/2" NMC, EMT, or Flex will be comfortably adequate.
2) Yes, EMT is acceptable as the EGC, but it provides a better ground return path to include a bare or insulated grounding conductor. And yes, every box must be bonded, generally by looping one of the EGC's around the grounding screw before nutting the EGC's together. If you don't run an EGC, then any receptacle's ground terminal must be pigtailed to the box, unless the receptacle is identified as suitable for grounding through the box-mounting screws. Even then it's good practice to pigtail them - it guarantees the ground path even if the mounting screws are loosened or removed.
3) To anchor to concrete, you'll need a percussion (hammer) drill and a suitable bit. You can use a regulary rotary drill and masonry bit, but the drilling will be tedious. You can use metal anchors and screws or masonry screws alone (Tapcons). I prefer the Tapcons. They're expensive, but save time and make a very firm connection. I buy them in bulk, but I've seen them in boxes of 100 with the appropriate bit included. 3/16" x 1 1/4" would be the right size for box and conduit straps. They have combination hex and phillips heads. Use a hex drive for installation - it takes a bit of torque.
4) For a home workshop, two 20 Amp receptacle circuits for plug and cord tools sounds like a good plan. Running both circuits to each quad box and splitting the receptacles between them is also good design. This plan also allows you to install a 220V receptacle in any box, if you should eventually need that.
You do not need a double pole CB just because there are two circuits in each box, even if you use a multiwire (Edison) circuit with a shared neutral. If you do have a 220V receptacle in the circuit, or split a single duplex between the circuits (ie: two circuits feeding a device on the same yoke), then you need a double-pole CB. However, there's nothing to prevent you from using a double-pole and it's not a bad idea.
As to multiwire branch circuits: I happen to like them, they save copper and help with box and conduit fill. However, they have the drawback that if the neutral becomes disconnected, and you have devices plugged-in to both circuits, the connected devices will be "two-twentied". Just make your neutral connections carefully, particularly at the panelboard neutral bus.
The other drawback to Edison circuits is that GFCI receptacles will not work on them. In a residential basement, you should be using GFCI protection. You can only run the common neutral to the first pair of GFCI's - from then on the neutrals must be split. On the subject of GFCI's: The most economical design is to use a pair of them in the first box and then use their Load terminals to feed conventional duplexes in all the other boxes. This protects the downstream receptacles, and costs much less than GFCI CB's. However, if you want to install a 220V receptacle anywhere "after" the GFCI's, this won't work. In that case, you'll need a 110/220V GFCI CB to protect the circuit.
One additional thing to consider for a workshop is whether you should run a feeder to a "sub-panel" in the shop, and then run your branch circuits from there. If you think you might eventually expand this installation with additional circuits, it might not be a bad idea, particularly if it's a long run to the main panel.
I should probably give you the standard caution about contacting the "authority having jurisdiction" for the specific requirements in your area, pulling a permit, inspection etc. Nonetheless, I'm aware that sometimes electrical work is done without this legal requirement, and sometimes it's even safe and workman-like. Do some reading on the proper installation for the wiring method you choose. There are plenty of good books on home wiring. The place to learn is definitely not Home Depot. Be wary of advice in this NG as well (including mine for that matter). There's a lot of scary misinformation posted on electrical questions...
Good Luck,
Kenneth
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