Hi,
I was down in the workshop tuning up the band saw the other day and ran into a minor problem. When I plugged it in for the very first time it worked for maybe a few seconds and then tripped the switch. So obviously the 15 amp breaker will have to be replaced.
? is…. Can a 2HP Band saw that is now wired for 110volts run on a 20amp breaker efficiently or am I better off putting in a 30amp breaker. If I decide to go with the 30amp breaker I will have to replace the plug on the band saw so it fits the outlet I have in place for my 2hp table saw. I just assumed I’d be able to change the wiring on the band saw( a matter of taking off the covering on the band saw and adjusting the wires) so I could run it on 240volts and plug it into the same outlet I plug my 2hp t/s into. Not the case. plugs on both machines are different. This General International 17″ band saw apparently only draws 6amps running at 2Hp.
So if the band saw will run efficiently on a 20amp breaker maybe that’s the way to go. Otherwise I can just as easily have the electrician put in a 30amp breaker and replace the plug on the Band saw. That way I can use the same outlet to plug in the b/s and t/s.
Wanda
Replies
Wanda
Whatever you decide to do (and I apologize if you already know this) you will need to pull new wire. You cannot change from a 15 amp breaker to a 20 amp using the same wire as most likely the gauge of wire on the circuit was sized for the breaker. Generally, 15 amp circuits will have 14 gauge wire, 20 amp 12. Putting a 20 amp breaker in your panel where there once was a 15 amp is taking a shortcut to finding out how comprehensive your fire insurance coverage is.
Regard it as just as desirable to build a chicken house as to build a cathedral.
Frank Lloyd Wright
"15 amp circuits will have 14 gauge wire, 20 amp 12." Our garage started out with all 15-amp circuits, but the wiring is 12 gauge. Might depend on the electrician and whether it's part of an original construction, or an add-on.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Forestgirl,
I must protest ;o)
You left a vital word out of my statment.
Generally, 15 amp circuits will have 14 gauge wire, 20 amp 12
I have a friend who is an electrician and he will not use anything smaller than 12, so I know there are exceptions - hence the qualification.Regard it as just as desirable to build a chicken house as to build a cathedral. Frank Lloyd Wright
HI,
I better double check the gauge. My uncle suggested going with a 20amp breaker and I am assuming he wouldn't have suggested that unless the wire can handle that. Doesn't hurt to double check though. I remember asking him about the gauge while he was putting in the electrical outlet. Can't remember know if it was 14/12 gauge wire.
Thanks for the info.
Wanda
PS... if that wire turns out to be 14 gauge I might have to go with Plan B. replace the plug on the band saw to fit the socket I have down there for the 2hp table saw.
Oooo, sorry, my mistook. I was distracted by the "You will need..." part of the paragraph. ;-) Off to my corner now.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I'm no expert here so take this as a question:
Under max load I could see the bandsaw using over 15 amps, but Wanda said it ran for a few seconds. The continuous draw then shouldn't exceed 15 amps should it?
Jeff
A real 2 HP motor will typically be rated at around 20A @ 110V. Exact number varies based on efficiency, etc. but should be on the motor nameplate.Pete
Some times a breaker, which is carrying the maximum will hold the line for minutes, maybe an hour or more before it trips. Also, breakers vary vastly in their carrying capacity. I've seen an instance where the twenty amp breaker carried more that the two hundred amp main. Now that is where you run into danger. Most breakers are what we call "Oslo blow", meaning they can carry more that their rated capacity for an instant. Some motors can draw two or three times their running amperage in starting up. The breaker is designed to accommodate that characteristic.
I think you have a problem other than circuit size.
A 15amp circuit should not trip starting a 2hp motor under no load.
It should not even trip if you are making reasonable cuts.
hi,
Well I all Know is the saw is prewired for 110volts right now. If I want to wire it for 220volts I have to switch the wires. But you think that's the least of my problems right now...
Motor: 2HP, 110/220V, prewired 110v. So you're fairly certain it shouldn't trip the circuit especially since it's not under load? So what could be the problem?
Wanda
I'm not as certain. A cap start motor on a band saw wants quite a bit of current at startup and it takes several seconds to come up to speed. See also:http://www.iprocessmart.com/leeson/leeson_singlephase_article.htmPete
Wanda & all:Forget the HP rating. I have a 5.5-hp motor with 15-amp plug & which never trips a 20-amp breaker. Look at the motor spec plate. How many amps does it draw? See to it that the circuit is safe for that current or more. Also, no matter what, 220v is a better choice at half the current. BTW, if your motor draws over 15 amps, the plug that came on its cord should not be able to plug into a 15-amp socket, at least in the US.BTW, I know that my 5.5-hp motor rating is bald faced hype. That is what the HP rating game has become. LOL!Cadiddlehopper
Have to agree with the opinions that you need a 20A instead of the 15A if it's going to over-load. You don't by chance have anything else plugged in and running on the same circuit when you start your BS, do you? Fan or possibly a shop vac hooked to your BS for collection?
Will also agree that a 20A should be run with 12G wire. I ran 20A's down both sides of my shop through metal cable sheathing with outlets every 4'. If I run the TS with a mobile DC working on the dust port, they get plugged into a different circuit. 15A on the TS and 8A on the DC adds up to 23A and it's a guaranteed trip. And for that I'm glad somebody figured all that out "before the fire". :>)
Good luck...
SARGE.. g-47
Wanda,
I had a similar deboccle once with a Rockwell 10 table saw. I went to my buddy's house to look at it, where he had it connected to a 20A 110V outlet...tripped the breaker every time he fired it up. He had the motor gone through and everything looked fine, but the breaker still tripped. I think it was 1.5HP on the motor, can't remember the amps.
Anyway, I bought the saw and plugged it into my 20A 110V outlet and have not had problem one since.
The only thing we can think of is the difference between the two breakers.
Weird
Maybe just try a new breaker, same size, first.
Breakers often get tired and trip before they should. Why don't you trade out the twenty amp breaker with another in your panel and see if that solves the problem. If it does, you may want to discard the tired breaker for a new one
"This General International 17" band saw apparently only draws 6amps running at 2Hp. "
6A at 220V, 12A at 110V, but even that's not valid. You can't get 2 hp from 12A at 110V (or 6A at 220V). If it was 100% efficient, and had 100% power factor, you'd get around 1.75 hp, but in the real world, the best you could do is less than 1.5 hp (more likely 1.25 or less for a no-name asian import).
But even at that, induction motor startup current (locked-rotor, or inrush, current) is typically 4 to 8 times it's full-load rated current, which puts it at 50A to 100A when you hit the switch. With it's 17" cast iron wheels and 3000+ fpm blade, startup will take a little time. Add to that the fact that it's wired with 14 gauge copper, and the resulting (large) voltage drop will extend the startup time.
A typical 15A breaker can absorb large overloads for short periods (the larger the overload, the shorter the period), but it sounds like startup is pushing the breaker to the edge. It's also not uncommon for breakers to get "weak" as they age or are tripped multiple times - that comes up a lot on these forums, and a new replacement usually fixes it. I'd try running it on a 20A circuit before doing anything else, if one is nearby.
There's nothing wrong with switching it over to 240V operation, but you will have to change the plug to match the receptacle, which hopefully is the correct one for the circuit.
Be seeing you...
Yup, 6A @220 sounds like a true 1HP motor. Should be plenty for that saw though.Pete
If you could change the bandsaw and the outlet to 220 you would be OK. You would only draw about 7 A @ 220. If you've 14 ga wire, it can handle 7 amps (voltage doesn't count). You would not need new wire, and your 2 HP saw motor would run cooler.
Barry
your problem sounds like you may simply be running other loads(machines/lights) on this same 15 amp circuit, causing it to trip. Use a dedicated circuit.
Wanda,
I am forever amazed at how many people on this forum are asking woodworkers for advice on electrical issues. This is not a area you want to try to get by on "the cheap". The risks are too great!
I suggest you engage the services of a QUALIFIED electrician. The life you save may be your own!
Doc,Though in my old age I keep forgetting Ohm's law, like most power tool fanatics, I have learned basic wiring practice & safety. No matter what an electrician does wiring a shop, we can still burn it down using his wiring if we don't know a thing or two about the subject. Yes, we should call in the electrician at times, but we need some basic knowledge ourselves which I believe that most of us experienced woodworkers possess (unless hand tools are all we will use). We don't mind sharing our knowledge, especially if it will prevent an accident. A piece of that knowledge is: DON'T RELY ON HP RATINGS! Another, in agreement with your post, is to realize when the electrician must be called.Cadiddlehopper
Hi,
Don't worry I have no intention of doing any wiring myself. I will have a qualified electrician tackle that electrical.
I am not sure exactly what else might be running on that electrical circuit. That I will have to find out. Would be ideal to have a dedicated circuit.
Is there any particular reason band saws use different plugs than table saws and jointers? I noticed the 2 shorter prongs on the band saw run vertically) Thank god the plug on the jointer is the same as on the table saw. ( the 2 shorter prongs run horizontally)I can now plug the jointer into the same 250volt 30amp receptacle I plug my table saw into. Good thing because the jointer is wired for 240volts.
Didn't have time to call Emberley's Electrical today. I'll do that tomorrow. ]
Wanda
I agree with Caddidlehopper... it's good to have a general understanding of basic wiring. But for the more advanced wiring I would consult an electrician. I wouldn't want to burn down the house.
Receptacles and cord caps (plugs) differ depending on voltage, phase, amperage, and grounding/non-grounding capability. What you've described for your saw and jointer is either a 6-15 (250V 15A grounding) or 6-30 (250V 30A grounding). Hopefully it's a 6-30, since you said it was a 30A circuit. The 6-30 is much larger than the 6-15. Look here - http://www.leviton.com/sections/techsupp/nema.htm
Your bandsaw is wired for 120V, so it has a 125V grounding plug - most likely a 5-15 (125V 15A), just like most things in your house. It won't fit a 240V receptacle, for good reason. It will fit a 5-20 (125V 20A) receptacle, and even though it's not drawn that way in the link, the 6-15 plug fits a 6-20 receptacle.
If you were to reconfigure the tool for 240V operation, you'd have to replace the plug.
HTHBe seeing you...
Hi TKanzler,
Yes, obviously the origional plug won't fit a 250volt receptacle. What I'd really like to know is why the darn thing fits a (125V 15A) receptacle if it's going to trip the circuit everytime you plug it in and start up the saw. So I have only 2 options... replace the plug or replace the 15amp receptacle with a 20amp receptacle. The 15amp breaker would have to be replaced as well. But in order for the 15amp breaker to be replaced with a 20amp breaker the wire connected to the 15amp receptacle would have to be a 12gauge wire. And right now I'm not sure if it's a 12 or 14 gauge wire connected up to that 15amp receptacle in my workroom.
Would it be best to just replace the plug and wire the band saw to run on 240volts? (right now it's prewired to 110 volts.) Whatever is easier. If it is possible to replace the plug without too much trouble the machine would draw less amperage... That's a plus.
Wanda
The fact that the plug fits doesn't guarantee that it won't trip the breaker. This really isn't rocket science. Assuming the circuit is ok, your machine when wired for low voltage wants more power than that circuit can deliver. This is a very understandable for a true 2HP motor and not unreasonable for your 1-ish true HP motor. Since it's not clear that a 20 Amp breaker is a safe option, wiring the saw for 240 will cut the amperage requirement in half and will allow you to plug it into a circuit that is suitable for the load.Pete
Wanda,IMHO,1. Change your Band Saw motor wiring to 240v (plug too :) ).2. If required to be able to easily plug into 240v, have an additional 240v outlet box added, extending the existing circuit.Results:
1. You will be happier.
2. Your BS will be happier.
3. You didn't spend an arm & leg to solve the problem.
4. Your electricity bill will like it.Rule: (just to be super safe) (& no big deal)
Never use more than one 240v machine on that circuit at the same time.Comment:
Your existing 115v circuit probably has other things on it sapping some of the power not leaving enough for the BS. It's simple to switch the BS to 240... so, do it.Let us know what you end up doing, OK?Take care...
Hello,
After speaking to the electrician on the phone this morning I have decided to go with the easier of the 2 options. After checking with the local tool store to make sure it would not void the warranty on the Band saw I have decided to Change the plug on the band saw to fit the existing 30amp/250volt receptacle I have connected in the workshop. :) and I will wire the B/S for 220volts. Problem solved!
Amazing how Much I've learned this week on the forum about .... amperage/voltage and receptacle configuration.
The chart on Configurations for general-purpose nonlocking plugs and receptacles was helpful. Thanks T/Kanzler for posting the link for that info.
Hopefully by Monday when all the plastering and painting of the workshop is done I will have the B/S up and running. Can't wait to see how it performs under load.
Wanda
OK Wanda, have you done it yet?Do you like it?Just curious...
Hello Little Joe,
OMG! Have I done it yet? and did I like it?.. hmmmmmmmmmmmmmm
I'll Let you know when I've done it whether or not I like it. you'll be the first to know promise! LOL
Wanda
Oh Wanda,Yes, OMG!! :(I meant changing your bandsaw plug, etc.!! :) :)Sorry, I should have been clearer! :) :) :)lj
Wanda,Anything new?
Cadiddle,
I agree completely on the expert-calling. Nothing against electricians, but they're not all brain surgeons. I trust my own skills and knowledge more than anyone else. In the same breath, I also know when I don't know the right way to do it. Sometimes the electricians are always "experts," even when they don't know the correct way, either. After all, they're getting paid even for making mistakes.
What does the manufacturer recommend for the power circuit? Was anything else running on that circuit when you started the saw?
If the saw only ran (unloaded) for a few seconds, I doubt if the problem is your breaker. You say that the switch tripped. Was that the power switch on the saw, or the breaker switch?
HI DAve,
The breaker "tripped" seconds after I turned on the band saw. And it wasn't under any load. Now no other machines were in use at the time. Not even sure I had the lights turned on.
Anyways I'm going to have an electrician change the plug on the band saw and wire it for 230volts. That way it's only drawing 6-7amps at that voltage. I bought a 15amp/250volt male part which will fit into my specially made ext cord. Hopefully he'll be in early this week to do that. Then I can get started on my next woodworking project.
Wanda
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