Confused re Grizzly G0457 Specs

[John Mark Lane]

I just was on the Grizzly website, looking longingly at the G0457 bandsaw (again), and thinking about whether I should try to rewire for 220. Reason being, I was under the impression that saw wants a 30 amp line at 110.

Then I was looking at the main page for the saw and it says:

Motor: 2 HP, 110V/220V, single-phase, TEFC capacitor start induction, pre-wired 220V
Amps: 20/10

On the pdf "Specification Sheet" (under Gift Cabana) it says 30 amps at 110.

What gives here?

I may just call them up and ask them. If the saw will run on a 20 amp 110 line...then it could work for me. And I otherwise like it.

I know in another thread the notion was raised that the amp ratings are really to protect the wires, not the machine, and I do understand that (more or less). Still, I don't want to overheat lines or over-tax my system. Any thoughts on this incongruity?

Mark

[John Mark Lane]

Pretty bad when I'm replying to my own posts.

I called Grizzly just now and spoke with a tech support guy. He put me on hold and came back a while later and basically said that all the info they have is calling for a 30 amp line. I think he probably believed the saw would run on a 20 amp line, but for whatever reason, he probably felt he couldn't tell me that. Just a gut feeling.

Of course that just leaves me still in a bit of a puzzlement.

[Thomas Knapp]

I have a Delta 746 table saw. It has a 1.75 HP motor on it. Delta claims that is the largest HP induction motor that will run on a normal 110 circuit.

[Dave Gaul]

Sounds like the saw wants 20amps @ 110V to run.
Grizzly is saying that the circuit should be rated for 30amps.
If you start a 20amps motor on a 20amp circuit, you will trip the circuit for sure, unless you have an extended time-delay breaker...
A 30amp circuit would allow for plenty of starting surge current on a 20 amp motor

[Brendan Plavis]

And think our Mr. Gual has hit the nail on the head.... It is probably 20Amp continous, but 25 or 30 to turn over....

[Rod Sheridan]

Starting current on the motor will probably be in the 5 to 10 times full load current depending upon what locked rotor code number the motor is built to.

So for a 20 ampere motor, a rough estimate is 100 to 200 amperes locked rotor current.

A 20 ampere breaker will carry 100 to 200 amperes of current for a short time in an inverse relationship. (The higher the current, the shorter the time).

Bandsaws unfortunately, are often machines with a large amount of inertia, so the motor starting current persists for a much longer time period, than a table saw, for example.

The time period may exceed the 20 ampere breaker capability.

I personally have a 4HP saw/shaper and a 4HP jointer/planer rated at 16 amperes full load. (High power factor/high efficiency motor) and they both start and run on a 15 ampere circuit.

Home machinery rarely runs at full load, and if it does, it is for a short time frame.

Electrical codes require that continuous loads not exceed 80% of a circuit rating, so Grizzly would recommend a 30 ampere circuit based upon that, or based upon knowledge of the current/time period for start up.

Bottom line is that if it starts (which it may well do) you won't have any problem running it from a 20 ampere 120V circuit.

Regards, Rod.

P.S. If it was me, I'd run it from a 15A 240 volt circuit.

[Van Huskey]

Rod has it covered. Knowing your issues with extra wiring I would be wary of any BS that "requires" 30 amps. The saw could end up being a lot more expensive than you planned!

[John Mark Lane]

Thanks very much, guys. I really appreciate the help. I bought a book about electrical wiring today and I'm trying to educate myself so I can better understand my options.

[Dave MacArthur]

John, what Rod said. That is what I was trying to point out in your other thread-- of course Grizzly posts "Electrical requirements--30A circuit" because the first guy who buys one and has it trip his CB on his 20A 1930's circuit box, will be all over them. But the REAL requirements are driven by the motor amperage and start up load. So when they list the motor specs, they say "110/220 20A/10A", then recommend a 30A circuit to be safe.

Like Rod said, start-up is very high but can be handled via circuit breakers intended for motors. Totally acceptable. And your bandsaw will NOT be used CONTINUOUSLY at full load--most of the time it will be "idling" at significantly less. I gave you some nums to show that even under full-load (long board of tall resaw), the thing is still within 15A circuit almost and certainly 20A.

I'd still re-wire 240! I have a ton of links and good "how to" reading if you ever decide to go for it which I can PM you. When I installed a sub-panel and wired my shop with 9 circuits, there were 3 or 4 folks here at SMC whose knowledge was invaluable, Rod was one of them. Using the SEARCH SITE USING GOOGLE function, and searching on the Workshop forum here, will give you MASSIVE amounts of great advice from several licensed electrician/woodworkers who post there regularly.

[John Mark Lane]

Thanks, Dave, I was kind of hoping you would respond here. Between you and Rod and others I think I'm starting to better understand how all this works. I plan to talk to my electrician again about a subpanel. I think that's the way to go. Using less amperage and having stronger motors seems kind of like a no-brainer....

Mark

[Nathan Palenski]

Out of curiosity, what kind of 30 amp 110v circuit meets electrical code? Twist lock L5/L6? I've never used anything but 5-20s and 10-30s at home.

[John Mark Lane]

Out of curiosity, what kind of 30 amp 110v circuit meets electrical code? Twist lock L5/L6? I've never used anything but 5-20s and 10-30s at home.

I have no idea. Seems like a good question... I'm not an electrician but I don't recall any 30 amp lines in any of the several houses I have owned and built....

[Rod Sheridan]

A 5-30 is a 120V 30A device, available straight blade or locking configuration.

I would rather go with a 6-15 and use 240V than a 5-30 and use 120V if I had the choice.

Regards, Rod.