My garage had a single 15a circuit, which it shared with the mud room next
to it. That didn't leave much capacity for using any tools so I added a 20a
circuit.

I got into turning and had to put the lathe in the garage as I didn't have
room in my shop. I ran the 20a circuit over to it.

I just upgraded my shop to a cyclone, so I have a 2hp DC left over; oddly I
can't sell it for even a third of it's retail value, so I am going to keep
it use it with the lathe.

Obviously I don't have enough power in the garage and have to run a new
circuit, but what...

1) I originally figured it would be a 240v as the DC is 240v only, but
didn't see that a 240v circuit in the garage would be real useful in the
future, for me or the next owner.
2) Playing with the motor wiring, I thought it could be converted to 120v.
Tech support confirms that it can, but they call it 240v only because of
concern over voltage drop at 16a. I could install a new 120v circuit, about
50' long and 16a; there would be some voltage drop, but not too bad.
3) I have a roll of 12/3; I could put in a one outlet multiwire circuit for
the lathe and DC. Since they would always be running together, the voltage
drop would be driven down some. But I have been a little paranoid about
multiwire circuits after I found one in my bedroom was installed
incorrectly, and 12/3 is harder to work with than 12/2.

All three options are reasonable, none are perfect; which would you do?

"Toller" wrote in message

1) I originally figured it would be a 240v as the DC is 240v only, but
didn't see that a 240v circuit in the garage would be real useful in the
future, for me or the next owner.
2) Playing with the motor wiring, I thought it could be converted to 120v.
Tech support confirms that it can, but they call it 240v only because of
concern over voltage drop at 16a. I could install a new 120v circuit,
about 50' long and 16a; there would be some voltage drop, but not too bad.
3) I have a roll of 12/3; I could put in a one outlet multiwire circuit
for the lathe and DC. Since they would always be running together, the
voltage drop would be driven down some. But I have been a little paranoid
about multiwire circuits after I found one in my bedroom was installed
incorrectly, and 12/3 is harder to work with than 12/2.

All three options are reasonable, none are perfect; which would you do?

Best option is a 60A sub panel.

Toller wrote:

1) I originally figured it would be a 240v as the DC is 240v only, but
didn't see that a 240v circuit in the garage would be real useful in the
future, for me or the next owner.

240V is always useful. Welder, big saw, DC, bigger lathe, electric
heater, etc.

2) Playing with the motor wiring, I thought it could be converted to 120v.
Tech support confirms that it can, but they call it 240v only because of
concern over voltage drop at 16a. I could install a new 120v circuit, about
50' long and 16a; there would be some voltage drop, but not too bad.

16A is the limit for general-use 20A circuits.

3) I have a roll of 12/3; I could put in a one outlet multiwire circuit for
the lathe and DC. Since they would always be running together, the voltage
drop would be driven down some. But I have been a little paranoid about
multiwire circuits after I found one in my bedroom was installed
incorrectly, and 12/3 is harder to work with than 12/2.

Nothing wrong with a multiwire circuit...especially if you use a
double-pole breaker.

Personally, I'd convert the existing circuit to 240V and use your wire
to run a pair of 20A 120V circuits.

Chris

In article , Chris Friesen wrote:

16A is the limit for general-use 20A circuits.

This is incorrect.

16A is the limit for a continuous load (explicitly defined by the NEC as
maximum current for 3 hours or more) on a 20A circuit.

16A is also the limit for any *single* cord-and-plug-connected load on a 20A
circuit.

The limit for noncontinuous loads on 20A circuits is 20A.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Doug Miller wrote:

16A is the limit for a continuous load (explicitly defined by the NEC as
maximum current for 3 hours or more) on a 20A circuit.

16A is also the limit for any *single* cord-and-plug-connected load on a 20A
circuit.

Thanks for the clarifications.

In this particular case it seems likely that a 2HP DC is
cord-and-plug-connected, no?

Chris

In article , Chris Friesen wrote:
Doug Miller wrote:

16A is the limit for a continuous load (explicitly defined by the NEC as
maximum current for 3 hours or more) on a 20A circuit.

16A is also the limit for any *single* cord-and-plug-connected load on a 20A
circuit.

Thanks for the clarifications.

In this particular case it seems likely that a 2HP DC is
cord-and-plug-connected, no?

Not necessarily; it could be direct-wired.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Doug Miller wrote:
In article , Chris Friesen wrote:

16A is the limit for general-use 20A circuits.

This is incorrect.

16A is the limit for a continuous load (explicitly defined by the NEC as
maximum current for 3 hours or more) on a 20A circuit.

As far as I can find out, this is because most fuses or circuit breakers
may trip at less than 100% if the load is over 3 hours, but will not
trip at 80% or less. I believe the reason is heat buildup. Far as I know
it is not a safety limitation.



16A is also the limit for any *single* cord-and-plug-connected load on a 20A
circuit.

There were multiple proposals to change the relevant NEC section several
code cycles ago. One of the arguments is that UL allows equipment (like
hairdryers??) to have a 20A plug and have a load of over 16A (or it
might have been the equivalent 15A plug with load over 12A). Under this
code section it is a code violation to use that UL listed equipment. The
code panel response - 'we're right, they're wrong'.

(Another rationale to change the code was this is a restriction on how
the wiring is used after installation and inspection - there aren't many
of those restrictions in the NEC, and it is essentially unenforceable.
The 3rd argument was that 80% is applied elsewhere in the code to
continuous loads, as above. The code panel's response was 'the code is
the way we want it.')

[To dpb - I was not impressed with the action of the code making panel
on this; an aberration?.]



The limit for noncontinuous loads on 20A circuits is 20A.

(I agree with everything you said Doug.)

--
bud--