ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Light activation in closet by a broken connection?
by geoff in UK. 02/19/19 01:35 PM
AFDD's coming to the UK
by Texas_Ranger. 02/18/19 02:04 PM
by Texas_Ranger. 02/18/19 02:01 PM
by gfretwell. 02/16/19 01:08 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
1 registered members (Scott35), 12 guests, and 20 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Lathe motor #69138
08/29/06 06:01 PM
08/29/06 06:01 PM
derater  Offline OP
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
Re: Lathe motor #69139
08/29/06 06:38 PM
08/29/06 06:38 PM
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.

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

Joined: Dec 2000
Posts: 4,279
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

Re: Lathe motor #69141
08/29/06 07:11 PM
08/29/06 07:11 PM
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.


Re: Lathe motor #69142
08/29/06 07:47 PM
08/29/06 07:47 PM
derater  Offline OP
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?

Re: Lathe motor #69143
08/30/06 10:09 PM
08/30/06 10:09 PM
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.

Re: Lathe motor #69144
08/30/06 11:13 PM
08/30/06 11:13 PM
NORCAL  Offline
Joined: Sep 2002
Posts: 882
Go to page 13 of the manual, it already has a inverter.

Re: Lathe motor #69145
08/30/06 11:32 PM
08/30/06 11:32 PM
Scott35  Online Happy

Broom Pusher and
Joined: Oct 2000
Posts: 2,717
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!
Re: Lathe motor #69146
09/01/06 06:32 AM
09/01/06 06:32 AM
derater  Offline OP
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.


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


Member Spotlight
Portland, Oregon, United States
Posts: 404
Joined: March 2007
Show All Member Profiles 
Top Posters(30 Days)
Admin 9
Popular Topics(Views)
253,292 Are you busy
189,905 Re: Forum
179,625 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.044s Queries: 14 (0.007s) Memory: 1.0016 MB (Peak: 1.1690 MB) Zlib enabled. Server Time: 2019-02-22 02:14:32 UTC