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I recently purchased a MBAND18BX2203, Laguna Tools 18|Bx 3HP 220V 18" Bandsaw and need to wire a 220 Volt outlet.

I think I know what I need to do, but I have one question: I was confused by the breaker since the saw was described as one phase (specifically, the spec sheet says: "3HP, 220V, 1 Ph. 12 Amp."), but the breaker I selected will connect to both leads, each at 180 degree offset in phase. I am guessing that this ensures that one of the 110/120 volt connections is active at any one time, but wouldn't this make the wiring 2-phase?

Just to verify, the rest of the setup below:

Wiring diagram: enter image description here

The 18BX2203 has a 3 HP 220 volt 1 phase Leeson motor. I have residential 2 phase wiring and was confused if I needed to some each 120 from the same phase or from different phases.

The manual recommended that I connect the bandsaw to a 15 amp breaker but I wanted to provide myself some additional margin for a future tool but was also aware that tools use more power on startup. I initially was going to use 12/2 wire, but I decided on schedule 40 conduit with Thermoplastic High Heat-resistant Nylon-coated THHN wire.

Another question I had was the number of wires connecting to the outlet. I initially thought I would need to have 4 wires (a 12/3 wire), both a neutral and a ground in addition to two hot wires. After thinking about it a little bit, it made sense two use three wires total, since I was setting up a dedicated circuit and the ground and the neutral would be the same wire

Receptacle

The bandsaw came pre-wired with a 220V 3-pin plug. I used this page to make sure I used the correct outlet. One of the decisions I had to make was if I wanted to use a twist lock plug, but I didn't consider the benefit worth the extra work to re-wire the saw.

I decided on 20 Amp Commercial Grade Double-Pole Single Outlet, White which has two connections for hot and one ground wire.

Breaker

I think the 20 Amp Double-Pole Type QP Circuit Breaker will work if I connect the red and black to each of the 20 amps (but does this make it 40 amps)?

breaker

Wire

In setting up a 20-amp circuit, I had to make sure this worked with my setup. Per the table in the manual, I need at least 14 guage wire, so I went with 12 guage which I needed for the 20-amp breaker anyway.

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Our power into US houses is 240V single-phase, with a center tap. The center tap is called neutral. This is called "Split-phase" since you can grab the outer "phase" wires (hot-hot) or grab one phase and neutral for half the voltage.

If you're wondering, this was Edison's idea when power was DC.

The plug you need on the saw is a NEMA 6-15. It is literally in the drawing (you are seeing a side view).

enter image description here src

The socket you should install is a NEMA 6-15 or NEMA 6-20. Note the family resemblance.

enter image description here

Due to an exception in NEC, you are allowed to plug 15A-plugged loads into either a 15A or 20A circuit. Further, a 20A circuit is allowed to have 15A sockets on it (as long as there are 2 or more sockets, e.g. the above NEMA 6-15 will suffice).

  • If you cable this with /3 cable, simply cap off the neutral.
  • If you cable it with /2 cable, you MUST use tape etc. to re-mark the white wire to indicate that it is a hot.
  • If you use individual THHN wires, you MUST use a hot color (black brown red orange yellow pink blue purple) for the 2nd hot. Both hots CAN be the same color, in fact, I recommend it. There's no useful purpose in distinguishing them from each other, but with up to 4 circuits allowed in conduit, you want to distinguish them from other circuits.

For instance suppose you have a 120V and two 240V circuits in a conduit. The wire colors are blue white red red orange orange. Which ones are which? Easy. Orange-orange is a 240V circuit. Red-red is another. What's left?

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    For safety I would strongly recommend NOT using push-in outlets and plugs in a shop environment. The safest way possible is to put all the outlets on the ceiling using twist lock and drop the cables down to the tools so that you do not have cords on the floor to stumble over. Saws like a bandsaw often need to be used in the center of the room due to the work being large and needing clearance for it and it is VERY convenient to be able to walk 360 degrees around the tool without stepping on a cord. – Ted Mittelstaedt Nov 29 '20 at 20:05
  • How could Edison have had the idea for a center-tapped transformer when power was DC, if transformers don't work for DC? – Phil Frost Nov 29 '20 at 22:38
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    @PhilFrost Because Edison was generating the DC that way. Splitting DC supplies like that with "taps" is a recurring theme in Edison and GE designs of that age. Edison's goal was to reduce voltage drop - 220V distribution has 1/4 the losses of 110V. But DC switches need elaborate arc suppression so 110 was better for lighting than 220. 220 was better for motors. So the +110/-110 split service gave best of both worlds for 1 more wire. – Harper - Reinstate Monica Nov 29 '20 at 22:58
  • @TedMittelstaedt great point. Floor mount power sockets exist too, but you need to build them into the floor slab during concrete pour, and they tend to fill up with chips, dirt, or worse water. However having no drop cables might be good for an "island" of tools in the middle of a work space. – Criggie Nov 30 '20 at 2:31
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There is no two-phase.

Single or three.

The single phase in this case is 120V hot to neutral/ground, 240V hot to hot. 220V is a somewhat outdated nomenclature for the US system, but in most cases your tool has adequate tolerance to take 240 without problems.

In other countries with different systems, it might be 220, 230 or 240V (perhaps even 250) and it might be that voltage hot to neutral/ground, so the breaker would have only one terminal. In the US/Canada, you're tapping both sides of our "split-phase" to get a single phase of 240VAC for your tool.

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    There actually is a 2-phase, but it's weird as heck. It was basically two single-phase circuits set 90 degrees apart, and requires 4 wires instead of 3 but only carries about 14% more power for 33% more wires. Needless to say it wasn't popular. – Harper - Reinstate Monica Nov 29 '20 at 6:03
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The following is all for a "typical 240V circuit in a 120V/240V US system". For all practical purposes, that is what is referred as "single phase". There is a split (to get 2 x 120V out of 240V) but it is still just really single phase. The alternative is "three phase", which is unusual in residential applications.

I am a bit concerned about the "sounds like this might work" nature of some parts of the question. You may want to consider getting a professional involved, but doing a lot of the grunt work (e.g., running the conduit) yourself to save money.

1 - A device will typically use 120V = hot + neutral, 240V = hot + hot (your device) or 120V/240V = hot + hot + neutral (e.g., typical electric dryer or oven)

2 - When a device talks about current, that is the same whether it is a single hot = 120V or two hots = double-breaker = 240V. It isn't double=20A + 20A = 40A. Rather, the double is 20A @ 240V instead of 20A @ 120V.

3 - All modern circuits should include ground. That is a separate wire (green or bare), except that metal conduit can also perform the ground function (with ground wires attached to the metal boxes where needed).

4 - You can't combine neutral and ground, except with very limited grandfathered exceptions. But for a new circuit, if you need neutral (it appears that you do not for this particular device) then it must have a separate wire (white or gray) from ground (green or bare). In your specific case, it appears that the device does not use neutral. So you can't combine neutral and ground, but you can simply not run a neutral wire, provided the receptacle & device don't need one.

5 - Conduit is a good idea, as it lets you add neutral if you need it, upgrade to larger wires if you need them, etc.

6 - Breaker size is dependent (generally) on two things - it must be both no larger than permitted based on wire size (e.g., if you use 14 AWG wire then the largest breaker you can use is 15A, if you use 12 AWG wire then the largest breaker you can use is 20A, etc.) and it also must match the device specifications. If the device is a receptacle then normally that will determine the required breaker size, with some very specific exceptions. But determining the receptacle size (and if the receptacle can be paired with multiple breaker sizes, determining which breaker size) depends on the devices being connected. You, as the user, do not decide "motor startup needs more so I'll upsize things". It doesn't work that way! The manufacturer is supposed to design the equipment and work with UL/ETL/etc. guidelines to determine the appropriate connection method (including receptacle size/type for a plug-in device) and breaker size.

7 - I don't know where the 15A recommendation came from. Checking the specs on several web pages, it shows 12A motor with 20A recommended breaker.

8 - GFCI is gradually being required in more and more places. Whether you need it on this particular 240V circuit will depend on a bunch of factors. I would actually recommend it even if you don't absolutely need it, because there are certain failure modes where GFCI will provide a human safety fast shutdown that can save lives. Of course, with this type of equipment there are a lot of other safety issues to be concerned with - eye protection, hearing protection, etc.

9 - Make sure you have the correct breaker for your panel. The pictured breaker is right for certain panels. But there are others will it will seem basically correct but not actually function properly & safely.

10 - According to spec pages that I could find, this particular saw is not UL-listed. That may be simply paperwork. But it may be a sign of substandard construction that can't be properly listed. There may be alternative (e.g., ETL) certification that is just not included on the web pages. But it is worth investigating before spending that much on a potentially dangerous piece of equipment.

11 - Question talks about receptacles but never names the type. There should be something - e.g., NEMA 6-20. What does the manual say? What type of receptacle did you buy?

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    Strange, the manual says 15 amp, but the website says 20 amp. I'll go with 20. Thanks for the great answer. – bonhoffer Nov 29 '20 at 12:59

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