Can some please explain this to me

 

Subject--table saw that can run on 110/220v. Disregarding all the hoopla of being more/less efficient etc.

 

If you have a 110v device pulling 15 amps, protected by a 20 amp breaker over a 12awg wire w/o tripping the breaker. I get the 20 amp breaker (10% over the 15 amp draw)

Everything is good so far.

 

Now I want to make the saw run on 220v.

So we now run the saw on a 20 amp breaker (or even a 30 amp breaker) on a 12 AWG wire.

Why??

why don't we run it on 10 amp breaker? (more probably a 15 amp breaker) on a 14 AWG wire

if you're splitting the load over 2 wires (red/black) the current s/b 7.5 amp per wire. 110% of 7.5 is something like 8 or 9 amps so a 10 amp breaker should do but 15 amp would be better (and more common & easier to obtain?)

 

In short, why don't we normally go to a smaller diameter wire instead of staying with the 12 AWG?

Is it b/c we just reuse the 110 wire (white & black) just to avoid pulling a new line? or is there something else involved in this?

 

If it were a completely new run I wonder what an electrician would pull as a matter of routine/habit.

 

Again for a saw not a dryer or stove/oven, welder.

 

thks

smitty

I'm not an electrician and don't even play one on TV but the wire size/breaker size/circuit voltage may have something to do with the National Electric Code requirements.

21 minutes ago, smitty10101 said:

Can some please explain this to me

@Artie, @Roly @DuckSoup...can you weigh in on Smitty's questions? Thanks in advance for your input.

You can, and I have, run the lower gauge wire for an appliance on 220 volts. The relationship on single phase volt/amps is pretty linear, whatever percentage one goes up, the other goes down.  I would never run less than #12, just for future considerations. Always nice to be able to have a 20 amp circuit, if needed. Some equipment does state the minimum, and maximum, overcurrent protection required. But if specific maximum overcurrent is not required (which is probably most single phase woodworking machinery) a 220 volt, 20 amp circuit, could be used for multiple tools/machines. From what I’ve read, there is very little, if any, advantage to running single phase equipment at 220 volts, other than a faster ramp up speed. Now I use a Shopsmith, and have the new power head. It puts out 1 3/4 horse power at 120 volts, but 2 horsepower at 240 volts, so definitely an advantage, but I can’t explain how it’s done. Right now the Shopsmith is the only piece of equipment I have that uses 220, but if I ever get around to putting in some supplemental electric heat, it WOULD be 220 for sure. Rule of thumb on breakers is 125% of rated load, or 80% of breaker rating. Being the NEC of course there are many exceptions, and specified use/location requirements. Dunno if this helped, but ask away   Oh yeah, I is a journeyman sparky in NH, and journeyman and master sparky in the Commonwealth of Massachusetts. 

8 minutes ago, Artie said:

but if I ever get around to putting in some supplemental electric heat, i

 

 

On supplemental heat I already had a 30 amp breaker with 10 gauge wire for a Heat pump unit.  Wire from breaker to outlet was 16 inches.  Never had any trouble but could have easily run 12 gauge and been within code.  Better at the time seemed like an investment for later.  This past winter I bought a 220 heater that required being hardwired with 10 gauge wire to a 30 amp circuit.  But hey I already did that.  Just changed the outlet and used a Drier cord.  Having gone a tad better I made out long term.  By the way this heater works great for my 16x20 shop.  Have yet to run more than 2 hours entire winter.  Land up cutting it off when far side of the shop gets to 70⁰  Maybe an hour?

 

 

As for original question have no idea really.  I have 220 for the compressor and the heater but only because they came that way.  Everything else runs off 110 with 20 amp circuits.  Bigger shop with say 100 amp service I probably would over time and budget providing upgrade to 220 machines.  My idea on this is I move machines from time to time and currently don't want to constantly run new legs of 220.  Call me lazy... 

15 hours ago, smitty10101 said:

If you have a 110v device pulling 15 amps, protected by a 20 amp breaker over a 12awg wire w/o tripping the breaker. I get the 20 amp breaker (10% over the 15 amp draw)

  The purpose of the breakers are to protect the wire not the equipment.

 

15 hours ago, smitty10101 said:

Now I want to make the saw run on 220v.

So we now run the saw on a 20 amp breaker (or even a 30 amp breaker) on a 12 AWG wire.

Why?? 

why don't we run it on 10 amp breaker? (more probably a 15 amp breaker) on a 14 AWG wire

if you're splitting the load over 2 wires (red/black) the current s/b 7.5 amp per wire. 110% of 7.5 is something like 8 or 9 amps so a 10 amp breaker should do but 15 amp would be better (and more common & easier to obtain?)

 

 Same size wire,#12, but different types have different ampacities.

Length of the wire run affects this as well. Longer run will normally have larger wire size to account for voltage drop.

Cost between #12 & #14 is minimal. But #12 gives you a little room to work when it comes to adding something else to a circuit.

If you were to run a saw and dust collector @ 220v you probably could run these on the same two pole breaker depending on the amperage draw. 

Like @Artie stated there are exceptions & other factors to consider. Exposing wire to its maximum rating over time can generates heat and premature failures.  

 

"If it were a completely new run I wonder what an electrician would pull as a matter of routine/habit".

As routine/habit I'm not sure there is one. Every job poses different challenges.

 If you were to run your wire in conduit and use #12 THHN you base your conduit size amongst other factors including the wire size and the amount of wires in the conduit.

Once you start adding more circuits into the conduit the amperage rating goes down while the conduit size goes up.

 

 

 There is no easy explaintion.

 

 

  

 

Edited March 21, 20197 yr by DuckSoup

It has been pretty will covered but like Artie I never run less than 12 ga and  a 20 amp circuit. The cost is minimal.   Roly

When the Electrician wired my shop,he used all #12 wire and 20a breakers. There is a 110 4 plex every 8" @ 4'off the floor , and every 8' in between a single 30a. 220v. outlet.

I run the RAS on 220v, 14" band saw 220v. 12" TS 220v, and 3hp DC 220. Everything else is 110v.

I found on the TS, if I ran it on 110v that it would bog down and burn on cuts over 3/4" thick. Since I wired it to 220v. It doesn't bog down even @ full height rips.

Herb

2 hours ago, Dadio said:

I found on the TS, if I ran it on 110v that it would bog down and burn on cuts over 3/4" thick. Since I wired it to 220v. It doesn't bog down even @ full height rips.

Herb

I'm sure that a few folks out there if they encountered that problem they would think that they need a bigger saw such as a 3 hp cabinet saw, or someone would recommend one. I have a 1 1/2 hp saw wired for 230 V and it's all I need.

2 hours ago, Dadio said:

When the Electrician wired my shop,he used all #12 wire and 20a breakers. There is a 110 4 plex every 8" @ 4'off the floor , and every 8' in between a single 30a. 220v. outlet.

I run the RAS on 220v, 14" band saw 220v. 12" TS 220v, and 3hp DC 220. Everything else is 110v.

I found on the TS, if I ran it on 110v that it would bog down and burn on cuts over 3/4" thick. Since I wired it to 220v. It doesn't bog down even @ full height rips.

Herb

I am only an old geezer, learn’t my electrical at the voke school back in the 70’s. I have read where motors will have more power at 220 over 110, they will run cooler at 220 over 110. I have read (on WW’ing forums) arguments from electrical engineers that there is no difference, with large mathematical formulas being shown, blah, blah, blah. 220 equals lower amperage on wires, uses up more breakers in panel. For hobby woodworkers probably doesn’t make a whole lot of difference. Commercial shop is gonna be 3 phase (if available), and as a high a voltage as possible, all day long. Now if you mosey over to the Shopsmith site, and read their specs on the Power Pro (or whatever their official name is ) head, if gives a horsepower of either 1.5, but I think it’s 1.75 horsepower at 110. Wire it up to 220, and they rate the horsepower at 2, So it makes a difference there. On the same site a gentleman there posted that sometimes, not always, but often, when his DC was winding down it would trip the GFI breaker. He had it wired into a remote controlled outlet. I had the thought that it was a single pole control, and only one side was backfeeding into the GFI, thus causing the imbalance and tripping the breaker. He also stated that when it happened it was always after the click of the centrifugal switch going back to the start coils in the motor. Well all the smart people over there told me how wrong I was, and went to great length explaining how this wasn’t possible. I dunno, I’m not that smart. But I made up an isolation relay outta some used parts we had in the shop. When the remote control plug in was turned off, the relay opened, and the two conductors from the DC were no longer connected to the breaker. His problem went away. I talked (typed actually) with him recently, problem is still fixed. Tomorrow we will talk about lightning strikes, class LOLOLOLOLOL.

I'll leave electrical stuff to the pros. I know only enough to be shockingly dangerous. It's revolting, I tell ya. 

@Artie I am glad you chimed in,Artie. I know less than @Gene Howe about electricity,except that sometimes one wire is white and another black and green  and once in awhile there is a red one thrown in, along with the purple,brown blue and yellow.

But I did see a difference in the table saw between 110v. and 220v., I was always blowing the breaker ripping wood larger than 3/4" thick, and leaving burn marks from the saw bogging down and stalling. Now on 220v it just eats right through the board,not even slowing down.

 

Herb

1 hour ago, Artie said:

Tomorrow we will talk about lightning strikes, class LOLOLOLOLOL. 

I will talk about Lightning strikes as that is what burned down my last shop and house. Lightening hit the power line and back fed into my garage shop and burned the shop and the house. At least that is what the State electrical inspector determined was the cause. It blew all the breakers out of the panel and the line voltage was feeding directly into the panel like an arc welder.

Herb

Lightning just doesn’t obey the rules of physics. On one job, the customers had attached a 10 foot piece of steel rigid conduit, across the joists of the roof rafters, for a clothes hanger. Not connected to anything, not grounded, just 3 clips holding it to the rafters.  A lightning bolt went through the roof, and basically incinerated the conduit, also created a pretty bad fire. The scaredest I’ve ever been was when I had the boat, and we waited a little too long to leave, even though we had been watching the clouds come in. (What can I say, the fish started jumping on our lines). We got to where the mooring field for the sailboats was, in a HURRY.  Wound up putting the canvas up during the torrential downpour. It’s funny now, but I don’t think my drawers were clean, then LOL. I got to see a water spout off of Cape Cod once, that was cool.  To get back to electrical, one of the bigger boats lost all their electronics from a lightning strike that didn’t hit the boat, just the water, but close enough to fry anything with a transistor in it. I can’t remember the price tag, but it was more than I paid for my boat. 

3 minutes ago, Artie said:

but close enough to fry anything with a transistor in it.

A number of years ago I was mowing what I call my upper acre...open area that had only young tree starts at the time. I had a nearly new, shirt pocket size, digital tune/display, portable radio I carried and used with ear buds. Ominous looking clouds began rolling in but I kept mowing...I saw a couple of cloud to ground lighting bolts well off in the distance...only a few more passes and I would be done...the next bolt to the ground I saw was much closer...I sorta' felt the hair raise on the back of my neck...concurrently the radio quit working which BTW allowed me to hear the thunder...I just made it to the garage as the t-storm broke loose...Apparently there was enough charge in the air from the last one to fry that radio....the digital display would no longer work. I took it as a strong warning. I finished the last few passes the next day. 

Glad you weren't using a pacemaker.

2 hours ago, Artie said:

Lightning just doesn’t obey the rules of physics. On one job, the customers had attached a 10

I lost 2 computers to lightening strikes, and the second one I had on a surge protector.

Herb

6 minutes ago, Dadio said:

I lost 2 computers to lightening strikes, and the second one I had on a surge protector.

 

 

Same, and the so called warranty on the surge protector was a joke.  My insurance company paid better by 250%.  

On 3/20/2019 at 8:09 PM, Artie said:

You can, and I have, run the lower gauge wire for an appliance on 220 volts. The relationship on single phase volt/amps is pretty linear, whatever percentage one goes up, the other goes down.  I would never run less than #12, just for future considerations. Always nice to be able to have a 20 amp circuit, if needed. Some equipment does state the minimum, and maximum, overcurrent protection required. But if specific maximum overcurrent is not required (which is probably most single phase woodworking machinery) a 220 volt, 20 amp circuit, could be used for multiple tools/machines. From what I’ve read, there is very little, if any, advantage to running single phase equipment at 220 volts, other than a faster ramp up speed. Now I use a Shopsmith, and have the new power head. It puts out 1 3/4 horse power at 120 volts, but 2 horsepower at 240 volts, so definitely an advantage, but I can’t explain how it’s done. Right now the Shopsmith is the only piece of equipment I have that uses 220, but if I ever get around to putting in some supplemental electric heat, it WOULD be 220 for sure. Rule of thumb on breakers is 125% of rated load, or 80% of breaker rating. Being the NEC of course there are many exceptions, and specified use/location requirements. Dunno if this helped, but ask away   Oh yeah, I is a journeyman sparky in NH, and journeyman and master sparky in the Commonwealth of Massachusetts. 

I converted my TS, Planar and Jointer to be 220 V becuase on 110 they would commonally trip a breaker on start up.

I do not use more that once machine at a time.  The 220 V consumes 1/2 the amperage that 110 does and produces less heat in the motor thus extending its life.  I have 2 220 circuits one for the tools and one for the DC which draws 13 AMP at 220.  Both are on a 20 amp circuit.

The breaker must be the failure point so if 20 A you must use 12 or larger wire.  

I have a armored cable 10ga that I use as an extension cord between the 3 220 machines.  

It has never even felt warm.

I would convert all tools (that are capable) to 220V.

They start up quicker, heat is less and less drawn thru you main panel to the supplier.

Thus they are cheaper also sort of what you pay for is KW and that is pretty much a wash.

 

I always like to plan for the eventualities. I may eventually want more 220 tools so plan for it. As well as the fact that that it may be less hazardous to have a higher gauge wire and breaker to reduce the chance of problems in the future. Also do not get the idea that 220 uses less electricity that has been proven wrong but a 220 motor in my opinion will last much longer. I am not an electrician but do a lot of my own 110 work.

    Thanks Artie I had not seen that about the 220 start up on motors