Stupid Electrical Questions

[Brian Holcombe]

Good morning gents.

I am awaiting a MM20 saw and in my evening hours I have been wiring the shop for it, along with a dust collector. I'm running separate conduits for each tool and, of course, separate breakers.

From what I have read the MM20 comes wired for an L6-30 Twist lock outlet, so I bought that outlet.

Am I correct in my understanding that what I need for this are two hots (red and black) and a ground (3 wire). I'm running individual wires through conduit, using 10ga copper.

I ran my wire with the mistaken assumption that I needed 4 wires, and so I have a white wire in the run, which now I believe I can simply cap off.

Is it a safe assumption that all 240v single phase tools that I purchase will be 3 wire?

I don't wire often, so sometimes it takes me a little while to get my bearings, so thank you for any help offered.

[Marc Burt]

Yes that's a safe assumption. Generally (very generally) speaking the only time you'll need 4 wire is something that has 110v run as well, like a stove with a 220 oven and 110 clock etc.

Also no need to run separate conduit. Both circuits can go in the same conduit so long as you don't exceed the full rate for the size conduit. That said, you're a better man than me pulling 10 gauge. I cuss like a sailor whenever I pull 12.

[John K Jordan]

Is it a safe assumption that all 240v single phase tools that I purchase will be 3 wire?

I can't speak for "all" 240v tools but all I have are 3-wire, jointer, tablesaw, bandsaw, lathe, air compressor, cyclone, welders, plasma cutter.

I believe some appliances such as clothes dryers use 4-wires, one a neutral, in order to run internal 110v control circuits.

I do all my own wiring but I am not an electrician (except in Mexico).

JKJ

[Ben Rivel]

Yep, all the 220v power tools I have come across were two hots and a ground.

[Brian Holcombe]

Thanks gents, much appreciated!

Yes that's a safe assumption. Generally (very generally) speaking the only time you'll need 4 wire is something that has 110v run as well, like a stove with a 220 oven and 110 clock etc.

Also no need to run separate conduit. Both circuits can go in the same conduit so long as you don't exceed the full rate for the size conduit. That said, you're a better man than me pulling 10 gauge. I cuss like a sailor whenever I pull 12.

It was one of those situations, where on the surface it appeared very easy, in reality not so much! I bought tight 90's for the corners at my ceiling, ugh...not fun.

[Mike Heidrick]

Do enough 10, 12 is a breeze.

[Ryan Mooney]

Thanks gents, much appreciated!



It was one of those situations, where on the surface it appeared very easy, in reality not so much! I bought tight 90's for the corners at my ceiling, ugh...not fun.

For those the generally recommended solution is to use boxes at the 90s and do the pull in stages (don't cut the wire, just pull in stages).

In fact there is a limit on the number of bends that are technically allowed without a pull box.

How many bends are allowed in conduit?

NEC 346-11: “There shall be no more than the equivalent of four quarter bends (360 degrees total) between pull points, e.g., conduit bodies and boxes.” TIA/EIA-569, 4.4.2.1: “No section of conduit shall be longer than 30m (100ft) or contain more than two 90 degree bends between pull points or pull boxes.

[Prashun Patel]

Are you certain it comes pre-wired with a plug? I just checked an older manual that implies that the MM20 comes with a short cord and junction box.

[Brian Holcombe]

For those the generally recommended solution is to use boxes at the 90s and do the pull in stages (don't cut the wire, just pull in stages).

In fact there is a limit on the number of bends that are technically allowed without a pull box.

How many bends are allowed in conduit?

NEC 346-11: “There shall be no more than the equivalent of four quarter bends (360 degrees total) between pull points, e.g., conduit bodies and boxes.” TIA/EIA-569, 4.4.2.1: “No section of conduit shall be longer than 30m (100ft) or contain more than two 90 degree bends between pull points or pull boxes.

Thanks for posting that up! I've been using pull elbows, which apparently negate this, but all things considered I've still be attempting to minimize how many corners I have.

Are you certain it comes pre-wired with a plug? I just checked an older manual that implies that the MM20 comes with a short cord and junction box.

I plan to leave my connection unwired until the saw arrives, but I read posts from Erik Loza saying they use L6-30's. If that is not the case, then I will terminate the cord with an L6-30, so that I can break the connection with ease if need be, but it will otherwise lock into place.

[Prashun Patel]

What DC did you get? Congrats by the way on your MM purchase. I know you have been eyeing it for a while. Your resaw elbow will thank you What blade did you purchase?

[Brian Holcombe]

Thank you! Haven't bought a DC yet, that will be soon and highest one on the list is V3000 from Oneida.

I bought a wood master CT 1" x 1.3T, and some sort of general use lenox bi-metal blade in 1" x 3t

I have a pile of wood waiting for resawing, so I'm excited.

[Ryan Mooney]

Thanks for posting that up! I've been using pull elbows, which apparently negate this, but all things considered I've still be attempting to minimize how many corners I have

Yeah minimal corners is always good

If you haven't found it yet the wire lubricant also makes pulling MUCH MUCH easier (and safer as you're less likely to stretch/break the sheathing).

http://www.homedepot.com/p/Klein-Too...1028/100660159

https://www.amazon.com/s/?ie=UTF8&ke...pull+lubricant

[Brian Holcombe]

Awesome! I will buy that for the next round.

Since we're on the topic of my problems, I will bring this up and hopefully one of you guys has experience this before and can offer a rememdy.

My electric box is set into the drywall, I'm running conduit on the outside of the drywall (interior of the room). What's the best method to break through and then enter the box? Should I run conduit behind the wall to the back of a junction box? Another method? I've also considered running flexible conduit behind the wall. Open to suggestions.

[Malcolm McLeod]

Awesome! I will buy that for the next round.

Since we're on the topic of my problems, I will bring this up and hopefully one of you guys has experience this before and can offer a rememdy.

My electric box is set into the drywall, I'm running conduit on the outside of the drywall (interior of the room). What's the best method to break through and then enter the box? Should I run conduit behind the wall to the back of a junction box? Another method? I've also considered running flexible conduit behind the wall. Open to suggestions.

I would be tempted to mount a 4x4 box on the surface of the drywall and use this as the origin point for the conduit runs. Punch a hole thru the back of the box into the drywall cavity that's common to your junction box (careful not to damage any existing wires). You can then fish your wires from the new box into the junction box and land them on appropriate beakers and ground lugs. You may also need to remove a knockout plug from the junction box on the side that faces your new 4x4 box. No need for conduit once inside the wall.

Another possible solution, instead of the 4x4 box, might be a pair of 'LB' fittings (one on each conduit run) that turn 90* into the wall, but serve as a relatively neat penetration into the wall cavity...?

Edit: I'd advise killing the main beaker when you get ready to stick anything metal into the junction box. Saves suddenly working in the dark!

[Brian Holcombe]

Thanks for the ideas!

I will certainly kill the breaker when working in the box. I'm brave....but not that brave.