I've got a new (to me) lathe coming in. It has a 7.5 hp motor, 3 phase.
I've got a 10hp phase converter for it, and in the process of having a
circuit added. What I dont know, though, is what size circuit should I have
installed for this? 50 amps? more? Less?

I'm sure this is a basic question, but i'm not an electrician. Thanks for
any info.

Greg Deputy wrote:

I've got a new (to me) lathe coming in. It has a 7.5 hp motor, 3 phase.
I've got a 10hp phase converter for it, and in the process of having a
circuit added. What I dont know, though, is what size circuit should I have
installed for this? 50 amps? more? Less?

I'm sure this is a basic question, but i'm not an electrician. Thanks for
any info.





It doesn't answer your amp question but you may be a little light
running a 7.5 off a 10 HP rotary converter. I'm running a 5hp 2 speed
from a 7.5hp converter and for 95% it works fine, but there are a couple
of gear changes it doesn't like. This is especially true when running
at the lowest speeds (low speed range on the motor). High speeds take a
bit of time for the motor to wing up to speed and that taxes the
converter also. One of these days I'll bypass the rotary and use a VFD
but I'm too cheap and lazy right now.

Koz

Full load amperage of a 3-phase 7.5 HP motor on 240 v is around 20 - 21
amps. The motor and phase converter should be connected to a 30 amp
breaker, at least. Best to check local "code" and install recommended
breaker.

Bob Swinney

"Greg Deputy" wrote in message
news
I've got a new (to me) lathe coming in. It has a 7.5 hp motor, 3 phase.
I've got a 10hp phase converter for it, and in the process of having a
circuit added. What I dont know, though, is what size circuit should I
have
installed for this? 50 amps? more? Less?

I'm sure this is a basic question, but i'm not an electrician. Thanks for
any info.

A 7.5 motor 220/3p will run all day on a 30 amp circuit, which only requires
10 gauge wiring. Matter of fact I recently wired a 7.5hp 3450 ventilator fan
for a truck garage.

Tony


"Greg Deputy" wrote in message
news
I've got a new (to me) lathe coming in. It has a 7.5 hp motor, 3 phase.
I've got a 10hp phase converter for it, and in the process of having a
circuit added. What I dont know, though, is what size circuit should I
have
installed for this? 50 amps? more? Less?

I'm sure this is a basic question, but i'm not an electrician. Thanks for
any info.