Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-08-2012, 05:37 PM   #16
Idiot Emeritus
 
Join Date: Mar 2008
Location: Fernley, Nevada (near Reno)
Posts: 1,625
Rewards Points: 1,044
Default

Is this Speedaire compressor wired for 240v?


That motor will produce right around 4HP continuously. It is 240 volt only, it cannot be made to run on 120.

Since it was in service when it was removed, I strongly suspect it will run just fine as-is when connected to a 240 volt source.

Code-wise, 430.51 (short circuit and ground fault protection) plainly states that the rules in article 240 (overcurrent protection) do not apply. Table 430.52 lists the maximum breaker size as 250% of the current rating of the motor. When a motor is marked in amps but not HP, the nameplate amps is used. Otherwise, the tables in the back or article 430 are to be used.

Technically, the maximum rating of the breaker supplying this motor would be 40 amps.

If this were mine though, I would put the 50 amp plug on it and not give it another thought.

P.S. The minimum wire size for most motors (including this one) is 125% of the current as determined above. With motors, it's perfectly code compliant to have a small wire connected to a larger breaker. For example, a 1HP motor operated at 120 volts can be supplied by #14s (or larger), and they can be landed under a 40 amp breaker (or smaller).

Rob

P.S. The starting current (as listed on the nameplate) is 93 amps. This is about normal for a motor like this one. This is also why we're allowed to increase the breaker size for a motor. A small breaker might trip on starting. The overload protection of the motor also protects the wire to it.

All motors require a disconnecting means (with a few exceptions), a cord-and-plug meets this requirement.


Last edited by micromind; 01-08-2012 at 05:42 PM. Reason: Added P.S.
micromind is offline   Reply With Quote
Old 01-08-2012, 07:43 PM   #17
Member
 
Join Date: Dec 2011
Location: Michigan
Posts: 843
Rewards Points: 500
Default

Is this Speedaire compressor wired for 240v?


Quote:
Originally Posted by micromind View Post
That motor will produce right around 4HP continuously. It is 240 volt only, it cannot be made to run on 120.

Since it was in service when it was removed, I strongly suspect it will run just fine as-is when connected to a 240 volt source.

Code-wise, 430.51 (short circuit and ground fault protection) plainly states that the rules in article 240 (overcurrent protection) do not apply. Table 430.52 lists the maximum breaker size as 250% of the current rating of the motor. When a motor is marked in amps but not HP, the nameplate amps is used. Otherwise, the tables in the back or article 430 are to be used.

Technically, the maximum rating of the breaker supplying this motor would be 40 amps.

If this were mine though, I would put the 50 amp plug on it and not give it another thought.

P.S. The minimum wire size for most motors (including this one) is 125% of the current as determined above. With motors, it's perfectly code compliant to have a small wire connected to a larger breaker. For example, a 1HP motor operated at 120 volts can be supplied by #14s (or larger), and they can be landed under a 40 amp breaker (or smaller).

Rob

P.S. The starting current (as listed on the nameplate) is 93 amps. This is about normal for a motor like this one. This is also why we're allowed to increase the breaker size for a motor. A small breaker might trip on starting. The overload protection of the motor also protects the wire to it.

All motors require a disconnecting means (with a few exceptions), a cord-and-plug meets this requirement.
I agree except I would at least #10 just because.
Hardway is offline   Reply With Quote
Old 01-08-2012, 09:12 PM   #18
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,876
Rewards Points: 2,106
Default

Is this Speedaire compressor wired for 240v?


Quote:
Originally Posted by Hardway View Post
I agree except I would at least #10 just because.
Because....... you like to waste money?
__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is offline   Reply With Quote
Old 01-08-2012, 09:47 PM   #19
Newbie
 
Join Date: Jan 2012
Posts: 6
Rewards Points: 10
Default

Is this Speedaire compressor wired for 240v?


So if it cant be made to run on 120v = wont run at all, then it should be ready to go since I'm assuming it was in service when disconnected. I was confused with the L1 and L2 on the wire diagram on the nameplate vs. the wire configuration of the motor. There is an extra terminal in the motor towards the bottom that is not identified by the wire diagram. I may call Grainger tech. tomorrow to see what each terminal is designated for.
tsayyote is offline   Reply With Quote
Old 01-08-2012, 11:06 PM   #20
Idiot Emeritus
 
Join Date: Mar 2008
Location: Fernley, Nevada (near Reno)
Posts: 1,625
Rewards Points: 1,044
Default

Is this Speedaire compressor wired for 240v?


L1 and L2 are where the incoming power goes. It doesn't matter which wire goes where, as long as there's 240 volts across L1 and L2, it'll run.
micromind is offline   Reply With Quote
Old 01-09-2012, 12:33 PM   #21
Member
 
Join Date: Dec 2011
Location: Michigan
Posts: 843
Rewards Points: 500
Default

Is this Speedaire compressor wired for 240v?


Quote:
Originally Posted by Speedy Petey View Post
Because....... you like to waste money?
Well see so say you Speedy Pete. How about free? THHN 12ga to 6ga free, no cost. The motor won’t fail either.
Hardway is offline   Reply With Quote
Old 01-10-2012, 01:32 AM   #22
Newbie
 
Join Date: Jan 2012
Posts: 6
Rewards Points: 10
Default

Is this Speedaire compressor wired for 240v?


Alright, ao I've got everything working now. I stopped by the previous owner's shop and as predicted by a few of you, the plug was changed to a 125v plug to match his receptacle even though it was wired up for 240v. tsk tsk tsk! Got the compressor wired in without changing any wires in the motor and she fired right up.

Thanks for all of your support!!
tsayyote is offline   Reply With Quote
The Following User Says Thank You to tsayyote For This Useful Post:
frenchelectrican (01-10-2012)
Old 01-10-2012, 01:36 AM   #23
" Euro " electrician
 
frenchelectrican's Avatar
 
Join Date: Apr 2006
Location: WI & France { in France for now }
Posts: 5,369
Rewards Points: 2,000
Default

Is this Speedaire compressor wired for 240v?


Just make a habit when you get done with compressour open up the drain valve to get the water and other gunk out everyday if you run it alot otherwise end of the useage.

And with fixed ( stationary ) units I use a rubber mat below the mounting feet the reason why I do that due cut the noise down a little and also give the tank some wiggy room to expand and contract a little.

Enjoy your compressour.

Merci,
Marc

__________________
The answer will be based on NEC ( National Electrical code ) or CEC ( Cananda Electrical code ) or ECF ( Electrique Code France )
frenchelectrican is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.