ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Recent Posts
300 watt transformer
by gfretwell. 10/23/17 10:21 PM
VFD MotorFeeders
by Yoopersup. 10/22/17 07:52 PM
Generator Cable Sizing
by brsele. 10/18/17 07:39 PM
What do you do?
by gfretwell. 10/17/17 01:08 AM
New in the Gallery:
Gallery Test
Popular Topics(Views)
241,472 Are you busy
177,483 Re: Forum
169,037 Need opinion
Who's Online Now
0 registered members (), 18 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#69138 - 08/29/06 07:01 PM Lathe motor  
derater  Offline
Joined: Mar 2002
Posts: 179
Hope this is an ok area for the ?. Cust. has a Powermatic 3520b lathe and all I can find is that it's 3 or single phase, 2hp. Someone (co. ?) told him it takes a 40a breaker. Does this seem excessive? Resi basement location.

Work Gear for Electricians and the Trades

#69139 - 08/29/06 07:38 PM Re: Lathe motor  
Bob  Offline
Joined: Feb 2002
Posts: 182
Mobile, AL, USA
Look on the motor nameplate and get the FLA
(full load amps). If its single phase the FLA should be about 12 amps. Use a 25 or 30 amp breaker. If its 3 phase the FLA should
be about 7 amps. 15 or 20 amps breaker. usually a residence does not have 3 phase service. You may have to change the motor.

#69140 - 08/29/06 07:57 PM Re: Lathe motor  
electure  Offline

Joined: Dec 2000
Posts: 4,262
Fullerton, CA USA
Don't be too quick to jump to the conclusion that it's a 230 volt wired motor.
A 2hp motor will draw about 24 amps when wired for 115.
If that were the case, a 40A Breaker wouldn't be excessive

#69141 - 08/29/06 08:11 PM Re: Lathe motor  
LarryC  Offline
Joined: Jul 2004
Posts: 783
Winchester, NH, US
If it a 3 phase motor, you can use a small VFD to generate the 3 phase from a single phase input.


#69142 - 08/29/06 08:47 PM Re: Lathe motor  
derater  Offline
Joined: Mar 2002
Posts: 179
Thanks guys. It's an either/or unit. I don't carry 8-2 in the van and was hoping against another trip for wire. Electure, is that run or start? Does that apply?

#69143 - 08/30/06 11:09 PM Re: Lathe motor  
RobbieD  Offline
Joined: Feb 2003
Posts: 231
Here is the link with the manual for the lathe. It seems wierd that in the specs it doesn't list the FLC. It does state that it is a 230v motor like you said single/or three phase.

#69144 - 08/31/06 12:13 AM Re: Lathe motor  
NORCAL  Offline
Joined: Sep 2002
Posts: 873
Go to page 13 of the manual, it already has a inverter.

#69145 - 08/31/06 12:32 AM Re: Lathe motor  
Scott35  Offline

Broom Pusher and
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
Viewed the .PDF manual, available from the link that RobbieD provided.

Found out the following about this Lathe:


[*] The Lathe Motor is powered and controlled via an intregal VFD, which is Factory installed,

[*] The Motor is a TEFC make, rated for 2 HP at 220V, 60 Hz,

[*] No indication if the 2 HP Motor is Single Phase or Polyphase - but seeing that the Motor is controlled by a VFD, I am thinking it would be a Polyphase Motor - likely a Wye connected TEFC type 3 Phase Squirrel Cage Induction Motor,

[*] The machine may be connected to either a 1 Phase 230 Volt power system, or a 3 Phase 230 Volt system,

[*] If 1 Phase 230 Volt, 2 Wire system is used, the Factory's Standard 3 wire cord, supplied with the machine, may be used and no alterations need to be made to the machine,

[*] If 3 Phase 230 Volt 3 Wire system is used, the cord needs to be changed out with a 12/4 cord, and termination alterations are required.

No FLA ratings are listed anywhere, so it seems like the Branch Circuit might be best rated for the FLA of a 2 HP 230 Volt 1 Phase Squirrel Cage Induction Motor.

As viewed by the NEC, this would result in at least 12 FLA for a 230 Volt Motor, and at least 13.2 FLA for a 208 Volt Motor.

Looks like a 20 Amp Circuit would be sufficient for the Lathe, and a Breaker from 20 Amps to 40 Amps could be used.

Definitely need to do these two things first:

1: Check the nameplate's ratings, and base circuitry ratings from that,
2: RTFM!!!
(stands for: Read The Fu..,, err... Fine Manual)


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#69146 - 09/01/06 07:32 AM Re: Lathe motor  
derater  Offline
Joined: Mar 2002
Posts: 179
Thanks all- I finally got to see the lathe; nameplate read 17.5a @ 240v 1ph.Used 10-2 for the circuit,20a bkr. Why 'they' told the h/o 40a is beyond me.

Member Spotlight
Alan Belson
Alan Belson
Mayenne N. France
Posts: 1,803
Joined: March 2005
Show All Member Profiles 

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.020s Queries: 14 (0.004s) Memory: 0.8017 MB (Peak: 0.9680 MB) Zlib enabled. Server Time: 2017-10-24 09:13:31 UTC