If you look on the nameplate of a motor they have a Service Factor number (SF).

"Service factor is a multiplier that is applied to the motor's normal KW rating to indicate an increase in power output or overload capacity that the motor is capable of providing under certain conditions. Common values of service factor are 1.0, 1.15, and 1.25".

A service factor of 1.2 can safely handle intermittent loads of 20% more than it’s defined horsepower.

Larger wire causes less resistance , less heat. A good thing.

 If there is room in your panel and the equipment is rated for 220v I would definitely do it. 

 If you are limited on space in your panel you can always add more than one receptacle on a 220 circuit and just run one piece of equipment at a time.

Make sure the devices you install are rated for the circuit. Don't put a 15a receptacle on a 20a circuit, that will be you weak link.

 Any electrical savings you generate in the shop goes out the window the second you turn on the microwave to warm the coffee.

8 hours ago, DuckSoup said:

Any electrical savings you generate in the shop goes out the window the second you turn on the microwave to warm the coffee

 

There's another reason that I don't drink coffee!  gave it up 20+ years ago & never looked back.

On 3/21/2019 at 12:18 PM, DuckSoup said:

 

Edited March 22, 20197 yr by smitty10101
double quote

I talked to an electrician today and his opinion was that when you bog down a motor on 110v and it reaches a certain point depending on the efficiency of the motor,i.e. the size, type and amount of field windings in the motor, the current draw will kick the breaker. If the same motor is hooked to 220v. it won't bog down and cause enough increase in current to cause the breakers to kick.

 

Herb

10 hours ago, Gerald said:

I always like to plan for the eventualities.

 

 

When possible always good move.

9 hours ago, Dadio said:

If the same motor is hooked to 220v. it won't bog down and cause enough increase in current to cause the breakers to kick.

 Going back to the OP, this is a good reason not to go with a smaller wire as this causes more resistance and generates heat. Having a larger wire that is only using half of its capacity at a minimal cost is a savings in the long run. You can safely rest the soft side of you hand, Do Not remove the dead front, on the face of the breakers in your panel and find the heavies loads in your house or shop just by the heat that you'll feel. The load isn't the only thing that can generate heat, something as simple as a loose screw or wire nut on a receptacle or breaker can do this.

 

 

 

 If you put an amp meter on a circuit that feeds a motor and turn the motor on you'll see a spike, maybe just for a second. The breakers are made in such a way to ignore that short term spike and lets the motor come up to speed and everything settles down. Years ago when everyone had fuse boxes the fuse would see that spike and blow. All it seen was that the amperage was more than it could handle regardless of time. To solve that issue was to install a Lincoln fuse. That was good until the house burned down.

 

  

2 hours ago, DuckSoup said:

 Going back to the OP, this is a good reason not to go with a smaller wire as this causes more resistance and generates heat. Having a larger wire that is only using half of its capacity at a minimal cost is a savings in the long run. You can safely rest the soft side of you hand, Do Not remove the dead front, on the face of the breakers in your panel and find the heavies loads in your house or shop just by the heat that you'll feel. The load isn't the only thing that can generate heat, something as simple as a loose screw or wire nut on a receptacle or breaker can do this.

 

 

 

 If you put an amp meter on a circuit that feeds a motor and turn the motor on you'll see a spike, maybe just for a second. The breakers are made in such a way to ignore that short term spike and lets the motor come up to speed and everything settles down. Years ago when everyone had fuse boxes the fuse would see that spike and blow. All it seen was that the amperage was more than it could handle regardless of time. To solve that issue was to install a Lincoln fuse. That was good until the house burned down.

 

  

The new AFCI breakers are supposed to detect this exact occurrence and trip. I have not seen this in action, only that this is why they are now mandatory for most residential locations per NEC. I have no experience with what I would call an electrical fire, but have seen plenty of burnt wires and wirenuts from loose connections, also have seen plenty of melted receptacles and switches. I would imagine that if this was as likely or prevelant as they suggest, our fire departments would be a lot busier. It is why when I had apprentices I would tell them the top two most important part of performing electrical work, was tight connections, and proper grounding. Even at the temperatures reached in the example, the metal box contained the fire. I have dealt with situations where I was very surprised that there was no fire, and the box contained the burning. They do make time-delay fuses for motors but now-a-days they are mostly commercial/industrial use.  With the pennies of today being made of zinc,  they might blow/melt faster than a 20 amp fuse  .

This was about our biggest electrical fire.   Basically a bad connection started a chain of events      138 kv      Roly  (picture from a local newspaper)

Edited March 23, 20197 yr by Roly

@artie

 

Since I'm old fashion I usually use metal boxes but the above comments concerning heat/fire brought a question to mind----

how much heat & how quickly will a blue plastic box take before it melts?

Also the various other colored boxes for low current--- iirc they are almond in color.

 

Btw--- going back to a previous post about getting into can lights from below---- I finally got my a$$ around to doing the job & you were EXTREMELY correct about the insulation, as much came down as I was trying to put it back up (loose cellulose). Finally gave up and swept it all into a bag. Will throw it back up in the attic---When I Get Around To It (wigati).

 

Again thks for the help

smitty

@DuckSoup and @Artie  This is all good information makes some sense out of electrical wiring.

 

Herb

23 hours ago, smitty10101 said:

how much heat & how quickly will a blue plastic box take before it melts?

Also the various other colored boxes for low current--- iirc they are almond in color.

  The is where the word "UL Listed" on the package come into play. You can search a part and find what it is listed or rated for. Plumping couplings will fit PVC conduit but it isn't listed for its use.

Edited March 24, 20197 yr by DuckSoup

8 hours ago, DuckSoup said:

  The is where the word "UL Listed" on the package come into play. You can search a part and find what it is listed or rated for. Plumping couplings will fit PVC conduit but it isn't listed for its use.

Ya gotta buy the matching paint and paint those elbows or the inspector is gonna notice fer shur.

1 hour ago, Artie said:

Ya gotta buy the matching paint and paint those elbows or the inspector is gonna notice fer shur.

 

Just paint it all same color, match taken care of.  

On 3/23/2019 at 11:20 AM, Stick486 said:

Someone forgot to say after kinking the wire you need to stick both

ends in the receptacle to trip the unknown breaker.