Mark J Posted March 25 Report Share Posted March 25 I'm wondering what's the most common arrangement for stationary power tools? I have a 240V TS and DC, along with a heater, that are all 3 wire. I can't think that I've ever seen a 4 wire stationary power tool, but then I can't say that I've every really looked. Is 3 or 4 wire dominant or is it a toss up? I'm looking at putting in a circuit for future use with a future tool, and I'm thinkin' I'd like to standardize the existing 240 circuits on one format of receptacle, so I can move things around more easily. Quote Link to comment Share on other sites More sharing options...
Tom King Posted March 25 Report Share Posted March 25 All mine are three wire. I can't think of a 240V stationary tool that requires a neutral wire, but there may be one. Quote Link to comment Share on other sites More sharing options...
difalkner Posted March 25 Report Share Posted March 25 Every 4-wire 240v circuit I've seen has been 3 phase. That's not to say there's not some oddball single phase 4-wire setup but in all my years working in plastics manufacturing and in larger shops, 4 wires means 3 phase. Quote Link to comment Share on other sites More sharing options...
JohnG Posted March 25 Report Share Posted March 25 I run 3 wire on both of my 240v circuits. One is dedicated to DC and the other feeds BS and TS, and I may eventually convert my drill press to 240v at some point. As mentioned above, I don’t think any single phase tools are likely to require 4 wire. 1 Quote Link to comment Share on other sites More sharing options...
gee-dub Posted March 25 Report Share Posted March 25 The 4th wire can be used to supply a correct 120v supply for a light, clock or other device, Like an electric oven with a light and clock. 1 Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted March 25 Report Share Posted March 25 I don't recall seeing this from any North American manufacturer, but a lot of the European equipment used in my industry includes a fourth wire on single-phase 240 volt circuits, that is an "earth" ground, separate from the neutral. This is what would be bonded to the cable shield to prevent EMF emmissions. Quote Link to comment Share on other sites More sharing options...
William R Posted March 25 Report Share Posted March 25 I think 3 wire 240v is common for tools and will stay that way for some time. But today’s welders plasma, mig are wired for a 4 wire plug. So depends on what you’re planning to use with that circuit. You can always run 4 wires and use a plug converter to 3 wire. If you run 4 wire 240v you can easily split a 120v plug next to your 240v Quote Link to comment Share on other sites More sharing options...
Mark J Posted March 25 Author Report Share Posted March 25 2 hours ago, wtnhighlander said: ... fourth wire on single-phase 240 volt circuits, that is an "earth" ground, separate from the neutral..... That's what I thought, the fourth wire is a dedicated ground wire. 4 minutes ago, William R said: You can always run 4 wires and use a plug converter to 3 wire That thought had crossed my mind, too. But it's good to hear that most power tools are 3 wire. Quote Link to comment Share on other sites More sharing options...
Mark J Posted March 25 Author Report Share Posted March 25 9 hours ago, JohnG said: run 3 wire on both of my 240v circuits. One is dedicated to DC and the other feeds BS and TS, On your BS/TS circuit, I'm curious, do you have two outlets, or a single outlet that the two tools share? Quote Link to comment Share on other sites More sharing options...
William R Posted March 25 Report Share Posted March 25 Yes here in the US the 4th wire (should be white) is run back to the breaker box to the neutral side. Quote Link to comment Share on other sites More sharing options...
William R Posted March 25 Report Share Posted March 25 18 minutes ago, Mark J said: On your BS/TS circuit, I'm curious, do you have two outlets, or a single outlet that the two tools share? Me to. You can run multiple circuits on 120v. But only 1 240v outlet for each breaker. I have a friend that wired his shop with multiple outlets 240v on 1 breaker and has no problem. I don’t know I haven’t tried it. I wired my shop my self ( yes it passed inspection) all my 240v circuits are protected by a single GFCI breaker Quote Link to comment Share on other sites More sharing options...
William R Posted March 25 Report Share Posted March 25 Reading in the internet it seams to be ok with multiple 240v outlets on 1 breaker. But you can’t go over the breaker amp rating. Or wire size. Like you couldent run 2 50amp machines on 1 50amp breaker. so multiple 240v outlets and 1 tool at a time or you’ll overload the circuit Quote Link to comment Share on other sites More sharing options...
Chestnut Posted March 25 Report Share Posted March 25 51 minutes ago, William R said: Reading in the internet it seams to be ok with multiple 240v outlets on 1 breaker. But you can’t go over the breaker amp rating. Or wire size. Like you couldent run 2 50amp machines on 1 50amp breaker. so multiple 240v outlets and 1 tool at a time or you’ll overload the circuit I think it depends. NEC States that you can run a multi-recepticle branch on 20A circuits but seems to say above that they have to be dedicated circuits. The it depends is different regions cite different electrical codes. For example Chicago is nefarious (typo for notorious but seems appropriate here) for being wildly different from NEC. My BS and jointer are both on the same 20A circuit but my DC and planer, 30a and 40a respectively get their own circuits. Quote Link to comment Share on other sites More sharing options...
Mark J Posted March 25 Author Report Share Posted March 25 14 minutes ago, Chestnut said: Chicago is nefarious (typo for notorious but seems appropriate here) for being wildly different from NEC. Hey! we resemble that remark, as in Chicago with a capital "C", and that stands for conduit, everything in conduit. 1 Quote Link to comment Share on other sites More sharing options...
JohnG Posted March 25 Report Share Posted March 25 On 3/25/2024 at 9:22 AM, Mark J said: On your BS/TS circuit, I'm curious, do you have two outlets, or a single outlet that the two tools share? I believe code says you can only have 1 receptacle on 240v circuits, but I have chosen to ignore this. My main 240 circuit runs to the TS, and I have a branch coming off of that at the BS, so they are both always plugged in. Since I’m a one man shop, and have a separate circuit for DC, both TS and BS will never be running at the same time. I don’t see why that’s materially different than unplugging one and then plugging in the other. If I add another branch for my drill press, I’ll still only ever have one tool running on that circuit. My lathe and DC are currently on the same circuit, but their combined amperage rating is still well below the breaker and wire capacity. The lathe was a recent addition, and I’ll rewire it to the TS/BS circuit at some point. My 240v circuit is 10ga SOOW, which is larger than any of the factory included power cables on any of the tools. 2 Quote Link to comment Share on other sites More sharing options...
Chestnut Posted March 25 Report Share Posted March 25 3 minutes ago, Mark J said: Hey! we resemble that remark, as in Chicago with a capital "C", and that stands for conduit, everything in conduit. Oh yeah i honestly forgot you were in Chicagoland. It might be a really good idea to seek the advice of the electrical inspector if they are willing. My gut is that anything over 20a will require dedicated circuits. Quote Link to comment Share on other sites More sharing options...
Mark J Posted March 25 Author Report Share Posted March 25 @JohnG, my thoughts exactly. @Chestnut, hey, I can't argue with the truth. I will be using an electrician, so it remains to be seen what they will agree to do. I'm actually OK with swapping plugs. Typically I use a long power cord/extension cord, which if left (on the floor) is a trip hazard. Quote Link to comment Share on other sites More sharing options...
Chestnut Posted March 25 Report Share Posted March 25 The thing that confuses me is NEC only requires 125% of motor name plate FLA. Most 3hp motors are 15amp and therefore would only need an ~18 amp breaker. However most 3 amp tools recommend a 30 amp circuit. Am I misreading the code? Where I'm going with that is a 20am circuit could cover multiple 3hp machines. My only hangup for doing that is yes it's a one man shop for me today but some day maybe one of my kids will have an interest in woodworking and want to join me. Or maybe I'll make a woodworking friend. With out dedicated circuits I'd never be able to run 2 tools at once. Some thing that happens more often is leaving 2 tools run and hop back and forth between them. Yeah there is probably a safety issue there. Most often for me this happens when doing thin slices at the bandsaw and want to clean the cut edge at the jointer. My BS and jointer on on the same 20a so I don't feel comfortable doing that. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted March 26 Report Share Posted March 26 @Chestnut, there is a lot of wizardry involved in how NEC determines its requirements, some of which derives from the expected use of the circuit. The 125% of FLA example covers normal, continuous use, which may (safely) be as high as 115% of the FLA with a typical service factor rating. The extra 10% is a "safety" factor above that, intended to avoid fires caused by an over-loaded (therefore overheated) circuit. But....an induction motor can have an "inrush" current in excess of 1000% FLA when starting from a standing stop. Even allowing for an energy / time trip curve, the 18A breaker would be tripping a LOT in that situation,and every trip degrades it. Tool makers allow for that in their supply circuit recommendations. Industrial motor control breakers can have trip curves adjusted to meet these conditions without such over-sizing, but your typical residential distribution panel breakers can't. 2 Quote Link to comment Share on other sites More sharing options...
Mark J Posted March 26 Author Report Share Posted March 26 FLA=? Quote Link to comment Share on other sites More sharing options...
gee-dub Posted March 26 Report Share Posted March 26 Full Load Amps 1 Quote Link to comment Share on other sites More sharing options...
Beechwood Chip Posted March 28 Report Share Posted March 28 I'd pull four wires to the outlet box. That way, I can wire it for a 240V outlet, or swap out the breaker and wire two 120V outlet circuits. I've re-arranged my shop a few times and needed to change 240V outlets into 120V and visa versa. 2 Quote Link to comment Share on other sites More sharing options...
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