I am setting up a new 8″ jointer and need some advice on the electrical connection.
230 v – single phase – 2 horse motor with a plate rating of 9 amps. I know that it will pull more than 9 amps at startup, bogging down, etc.
Question is should I put this on a 15 or 20 amp circuit?
Any advice (from a qualified person) is greatly appreciated.
Thanks,
BAP
Replies
You will be fine with a 15A circuit on 230V.
Normal running current should be somewhere between 5 to 7 amp, with a bit more at start.
If this circuit is dedicated to the jointer only, it will be OK, but personally I would use a 30A circuit, as it would allow me to use an additional load, on the same circuit, or alternatively a larger load at some point in the future.
I'm assuming that you will be wiring this circuit from either your main board, or a sub-board.
Willie
BAP,
I always figure on the higher side, at least double the operating current. The additional cost of heavier guage wire, breakers, and conduit up front is cheaper than ripping it out and doing it over again. If you're questioning the guage of wire to use on a run, always upsize the wire.
Thanks! I appreciate the advice. I am running this directly from a subpanel which is dedicated to the shop circuits.
BAP
I'd run 10 ga wire and use a 30 amp 220 volt breaker. This would allow you to plug in a tool which required more current. I'd also use a twist-lock plug setup. Doing this prevents the plug from inadvertently being disconnected. If you go to Home Depot you'll find Bryant receptacles and plug parts ... and you can buy number 10 wire to make your own cord.
John
Just remember that if you're going to follow the NEC, then you must use a 30A receptacle or receptacles on a 30A circuit, and 20A receptacles on a 20A circuit, unless there are more than one receptacle (on a 20A circuit), in which case they can be 15A. 15A circuits must have 15A receptacles only, regardless of how many are on the circuit. There are no restrictions against multiple receptacles on 240V circuits, either. Same rules as 120V circuits.
Be seeing you...
Check the inside of your magnetic starter and look at what current the overload protection is set at. I would guess it is set at 15 amps, that's what breaker I would use. I am assuming your jointer has a magnetic starter.
Life is what happens to you when you're making other plans .
BAP,
The recommended amp circuit should be noted in machine's manual - if not, check the load rating usually marked somewhere on the magnetic switch. If possible, it is best to run a dedicated circuit to each machine, thus avoiding tripping a breaker when (ex.) turning on the jointer and dust collector.
Unless the machine has some sort of overly heavy power draw on start up, stick with the recommended amp circuit. The natural inclination is install a bigger breaker than necessary (e.g. ... it says 15 amp - I'll put on a 30) - don't.
The use of a larger than necessary breaker could prove dangerous, and destructive to the machine plugged in to it. The use of a certain recommended amp breaker is determined based on the size of the motor (amps, draw, etc...). If a problem occurs during the use of the machine (e.g. bogging down, or a jam of some sort), the breaker will trip under the increased load - saving the circuit, the wiring, and most importantly, the machine's motor. If a larger than needed amp breaker is used, the machine will fight to remain on even if it is bogged, jammed, etc... until it reaches the critical draw high enough to trip the larger breaker. This could lead to a burned out (dead) motor, damaged wiring, or worse - some sort of mishap due to the obstruction.
Plug the machine into an outlet on a dedicated circuit using the appropriate amp size breaker.
If you have any questions, please feel free to ask!
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Jackie,
Your recommendations are the perfect way to go in an industrial environment, where you have dedicated equipment, wired to dedicated circuits.
In the home environment though, we normally size the circuit breaker, to protect the wiring and the receptacle. We therefore, normally rely on the machine's own overload protection, rather than the wiring circuit breaker.
If the jointer in question has no overload protection, your way is the only way. Otherwise, if it was me, I would have all my 220V outlets at 30A in a home shop.
Normally, at home, due to space constraints, we don't have the luxury of a fixed layouts, with dedicated placements, permanently, for each piece of equipment. Personally, I find every time I buy a new toy, the whole layout of my workshop changes. For this reason, flexibility is very important to me.
Willie
Edited 9/6/2004 11:28 am ET by Jellyrug
I definately agree with jackie. I am not an electrician, but I am a remodeler and as such have to deal with electric code and inspections every day. The previous poster was right about the outlet matching the source, you cannot put a 15A. outlet on a 30A. breaker. The jointer should not trip a 15A. circut on startup as breaker are a little slow to trip. You can draw 20A. on a 15A. circuit for a moment. If you do have a problem with tripping on startup use a time delayed breaker. These breakers allow the machine to over draw for about 4 seconds bafore they trip.
Over rating the supply to a machine is a bad practice and potientialy very dangerous. I have all industrial quality tools in my shop and I believe that very few of them actually have an overload protector, unless it is built into the magnetic switch. Think about tools like hand drills, sanders, smaller air compressors they will catch on fire before they trip an over rated circuit. As far as machines sharing a circuit there is usually not a problem for machines like a drill press and a sander to share. If you are having issues install a sub panel and run everything on seprate circuits. Or you can protect machines shareing a circuit using an apropiately sized breaker on the machine it self. THAT is how it is usually done in a large production shop. One 50A. circuit powering several 20 amp machines, each with their own breaker at the outlet.
If all the contrary opinions confuse you call a few good electritions and ask them. If they are good they will say the same thing. Enjoy the awsome new jointer.
Mikeplease excuse my spelling.
Mike,
Provided we stick to wiring code, I guess there is no right or wrong answers here.
Anything significant I have, is protected with a magnetic switch. Means I can plug it in anywhere, provided the circuit is big enough.
For a 2hp jointer, if it is not properly protected, you can buy a good quality magnetic switch for $50. This gives you thermal overload protection of 8.5 to 12 amps on a 220V circuit. More and most important is the safety feature allowing automatic shut down if the power is interrupted, so equipment will not start when circuits are turned back on. In my book this is the only way.
The smaller tools you refer to, are normally not protected, but they normally run 110V, off a normal household receptacle anyway?
Willie
PS. In a big shop all your circuits have to be labelled, with the correct spelling too. True, but just jokin
Edited 9/6/2004 12:38 pm ET by Jellyrug
Mike,
Magnetic switches do have overload protectors built into them, and they are designed to be adjusted to match the power draw of the machine they are connected to.
The primary purpose of a conventional circuit breaker is to protect the wiring in the walls, not what is plugged into the outlet, and the breaker should be matched to the code capacity of the wiring. If you feel that a machine needs protection, the overload device should be at the machine.
John W.
John,
Good post.
Electrical installation here in the US is always an interesting subject to me. I did my electrical training abroad, where houses were wired 230V and normal small to medium manufacturing used 3 phase 380V, everything 50 cycles. The good old days, when all house wiring had to be run in steel piping, inside your walls, to meet code requirements.
So, getting back to the original question, responses were requested from "qualified" persons.....
In Europe, a "Qualified Electrician", is someone who completed a four year apprenticeship, gone to electrical school and passed some sort of institutional test to get his Journeyman Certificate. Then, to do installation work, he normally has to pass the code test as well.
Here in the US, if you work in construction, or residential, you have to be a Licensed Electrical Contractor, and this includes passing a state test including code. If you work in an industrial factory, you normally have exemption and really the definition "qualified" is very vague. Anyone can be appointed in this job.
To address the original question, a "Qualified Electrician" understands motor starters, controls, VFD's etc., while a "Licensed Contractor" understands wiring code. In conclusion, I don't believe a "qualified" person exists for answering this question.
Your post was very "qualified" though.
Willie
John,
I agree that there are many situations in a well equiped shops were you can get away with over over rated breakers. I think that we need to be carefull when making blanket statements that this is always OK. For example "at least double the operating current" is wastefull at best and potientially dangerous.
I remember seeing in some of my machines that the mag switch includes overload protection. What about after market switches? Amperage draws vary wildly, especially at 220.
Mikeplease excuse my spelling.
Mike,
I didn't make the statement about double the operating current, somebody else did, and it was in reference to designing a circuit not about protecting the machine, and it was, in that context, basically good advice.
Again, the basic principle is that a circuit breaker is designed for, and is only intended for, protecting the fixed wiring of the circuit it serves. If the machine needs overload protection that should be built into the machine's controls. That way the machine is still protected if it is hooked up to a different circuit and the protection can be fine tuned to the size of the load and the way motors draw power, standard breakers aren't specifically designed for motor protection.
Magnetic motor controls, of the type we are discussing, have either an adjustable setting inside the switch box or a replaceable component called a "heater" that is matched to the motor's draw. An aftermarket switch could be either, but its catalog description should tell you what version it is and whether or not you need to order a heater element in addition to the switch.
John W.
Mike,
Most medium to lower end woodworking machinery will not have their own proper overload protection.
As mentioned, a circuit breaker in an electrical panel, is designed to protect the circuit, not the equipment being plugged into the circuit.
In an industrial environment, electrical distribution, including sub-distribution, is a complex subject, and fault, as well as overload protection is carefully designed to protect the electrical distribution systems at various levels. Specific equipment, is always protected within the item itself, either in a control panel, or in the motor starter itself, if this is a manual starter. A single phase industrial motor starter, will normally be made up from selected components, including either a rotary, or magnetic switch, and either a thermal, or solid state overload. These are available from many sources, being Cutler Hammer, Square D, etc. They offer precise overload protection and short circuit, or earth fault protection. A starter as mentioned here, wil run from $300 upwards.
In the small shop home environment, we have to be practical here. If you wire a receptacle, to plug in a 2hp 220V motor, with a 15amp circuit breaker, you don't gain much safety, over wiring for 30amps. If you have a short circuit, the 30amp breaker will do the job. If you have a motor running overload situation, neither the 15amp, nor the 30amp breaker will save you. The 30amp will be too big and the 15amp will not be precise enough. If you had a 10amp breaker, you will trip the circuit under certain conditions without danger to the motor and the 2hp motor could still burn it's windings if it runs for a long time, slightly above maximum load. In conclusion, you cannot offer full protection with a normal panel circuit breaker.
A 2hp 220V, single phase motor, normally has it's overload set at a maximum of 12amps. This kind of overload will also protect your motor, and trip if you are running the motor at 9amps for too long. Normal running load for a 2hp motor is around 7amps.
The cheapest home protection for woodworking machinery is buying a simple magnetic switch, with thermal overload, as posted in the link below. While this is fine for the small shop, I will not use it in a NEMA, industrial shop environment.
http://www.grizzly.com/products/item.cfm?itemnumber=G4572
WilliePS. Seems as if the link is not working, but you can look up the item number on Grizzly's site.
Edited 9/8/2004 12:52 pm ET by Jellyrug
Willie,
The industrial model that you described is what I would also use in my own shop if I were to oversize the supply (then you could call it a buss). This has been a very interesting discussion. I agree that theoreticly the built in protection should save the motor should things go wrong. However I wouldn't put all my faith in that little button on a $300 import band saw. BTW, I dont think that my 14" Delta BS has any protection. I know that residential code REQUIRES that the outlet match the supply. I've run into this on the job site during inspections (I sub out electrical to liscensed electricians). In the home shop? I assume that the NEC still applies. That said, knowing the inspectors in my town they would probably have a fit if they saw the wireing in my garage :-) Even though I doubt any of yall (or any wood worker or electrician for that matter) would have a problem. My electrical sub looked at it and said it was good. This is what is great about a site like this... you really can get a lot of different ideas, many good, and pick the ones you want. I will say this about calling an electrician, it can be very hard to find one who knows about this kind of thing. You might look for one that specializes in industrial work.
Mikeplease excuse my spelling.
Mike,
Agree, this was interesting.
If you are the only one using your equipment, you will normally have no problems. Let's face it, you have to do something real stupid, to burn a 2hp motor on a woodworking machine.
I use to run all my 220V machines with an extension cord from the 30amp dryer receptacle, in the laundry next to my garage. My main board was full and I hung in there for as long as I could.
I used the space in my board, taken by the 2 pole dryer breaker, to put in a 100amp breaker feeding a sub board in the garage. The way they build these houses, this was one hell of a job, to get to the top of the main board and pull the 100amp wires in.
Key is to make sure you don't have problems when you sell your house, with installations out of code. For those who don't have the experience, it is probably best to use an approved electrical contractor.
Willie
There is too much confusion on this site to get a reasonable answer to your question.
Most industrial shops have a large electrical buss with a breaker (fuse) box attached at each equipment drop. The breakers ans drop cords are sized to the machines. In addition each machine has its own thermal overload protection.
Most home shops have their breakers at the panel buss with a breaker sized for the equipment. Many home machines have thermal overload protection on the motor.
I would suggest a 15amp breaker/recepts for your machine. If you believe that you will want to use larger machines in the future, either run conduit or larger wire and chge the breaker and recepts.
(You will will note that my suggestion mirrors industrial practice as much as possible.)
George,
I agree, too much confusion here, but I guess this is what happens when woodworkers talk about electricity.
All I can add, is "when in Rome, do as the Romans do". So this is what the NEC (National Electrical Code USA) says.
For anything above 1hp:
Article 430-22: The circuit supplying your motor, or machine, must be sized to at least 125% of the full load current rating. There is no mention in the code, about over-sizing the circuit. The code further specifies that the circuit must provide short circuit and earth fault protection for the circuit.
Article 430-42 item (c): If a machine is cord and plug connected, above 1hp, the overload device must be an integral part of the motor, or the machine.
In short, this means he can wire his 220V circuit to anything he wishes, provided it is minimum 125% of the full load. It also means he must have overload protection on his jointer.
With the latter part, we all seem to break the rules.
Willie
PS. Then there is your local state code, but I don't know where you are.
Edited 9/8/2004 5:31 pm ET by Jellyrug
Hey BAP,
I think the best thing you can do is to ask around your neighborhood, friends, local merchants to see if you can find a GOOD electrician who is available for small jobs and fork over the money to have someone who knows what they are doing keep your shop from going up in smoke and your jointer from frying.
Several people have made statements that were accurate, have been disputed by others who knew something but not enough to know what they didn't know, and several whose experience doesn't fit the home shop environment.
This is not the place to get electrical advice. After all the verbage can you tell me for sure who is right?
John
BAP,
This will help, I'm sure. It's well written and informative.
http://home.att.net/~waterfront-woods/Articles/Electricity/electricity.htm#Motors
Willie
Don't exceed 60% of the breaker capacity. I would put it on a 20 amp.
The manual should tell you what to use. I think a 30 amp circuit is a bad idea, if the motor were to overheat, it would take longer for the breaker to respond. a 2hp single phase 240 volt motor isn't going to be cheap. I would put it on a 20 amp myself, If you trip the breaker you are pushing the equipment too hard.
Just my 2 cents worth, satisfaction guaranteed or your money back.
Dem,
I agree with your advice. I am surprised that one thing that has not been discussed here is the startup current, which typically is higher than the operating current. With many of the import machines, it is hard to trust the labeled ratings. On one of my machines it was labelled at 18A operating, but the startup current was 38Aand operating under normal load of 27A. The manufacturer was kind enough to replace the motor with one closer to spec. If there is any question of the acutal draw, I suggest placing a meter on the load and doing an averaging.
Another factor which will affect circuit performance is the breaker and the speed of tripping. A hi mag ( I believe that is the term - been a few years since I put one in) will not trip immediatley, but only on extended periods of time of over current. This breaker is not typically available at the box stores, but a trade suppliers.
Also, how many of you are using GFI circuits where they are required by code?
I'm interested in seeing how many of the replies here are from people in the electrical trade or have worked in the electrical trade.
Craig
I am a maintenance mechanic, and deal with these situations daily on an industrial level. Most of my experiance is with 3 phase 480 volts, although I do see 208 and 240 single and 3 phase. If I was to hook that up for my employer I would go 20 amp, 10 gauge wire. Run conduit to it, to a 4" box, and put a tiwstlock receptacle in there, Preferably a Hubbell. Put a twistlock plug on the jointer, again use a hubbell brand. I am curious about what brand your electric service is. That makes a differance, I hope it isnt Federal Pacific, as then you may as well burn your house down today. Hopefully you have SquareD, (not homeline). Good Luck!
Dem,
Does you boss allow you to do electrical work in the factory, or industrial environment where you are employed?
Just curious, as I'm running two large food processing factories (1500 employees) and we are always curious as to exactly what OSHA implications are, in terms of who has access to electrical panels.
Willie
PS. Are you close to California, always looking for good people here.
I go into all the electrical panels, that would fall under your insurance carrier. keep a codebook on the shelf, follow it and strictly enforce a lockout tagout program. OSHA will want to see your lockout tagout paperwork, your confined space paperwork msds's, permits for your stacks etc. Been to many OSHA "raid" classes, (provided for free by our insurance carrier)I dont call an electrician in unless a new panel is installed, or the conduit gets up to 2 inches and the wire cant be pulled by feasible means. Now of course California State Law or local Law could overstep this, I am in Wisconsin and we can work in the panels, however a day will come when a Journeyman is required to do the work here, this has been rolling around the area for a long time. Then I guess I go take the test. I prefer to just program the PLCs and work in and build contol panels though. I would contact your insurance carrier, they should be able to answer any questions on who can work in the panels, If they cant I would find an insurance carrier who will. The insurance companies are very happy to work with you on this stuff and many other things to keep your claims down and their payouts down.
Dem,
We have two Electrical Engineers, one at each factory, two Electrical Supervisors, six Electricians. Each Supervisor, has an Electrical contractors licence. We run 3 shifts, 24 hours.
We don't allow mechanics into our electrical panels, as even though we are insured, if someone is killed, we are liable to prove to OSHA that we have taken all the necessary precautions to prevent the accident, including skills competence training. If you have been doing electrical work for some time and you are competent in this area, you should look at having yourself clasified as an Electrican.
Willie
The Electrical requirements are rolled into my job description, I am also required to use insulated tools, mats that prevent grounding, hardhats, and hot gloves when in the panels.
I do know that a couple of my co-workers did some electrical work at our California warehouse, and I did do a bunch of work in a plant in Washington State without any complications.
Ditto. Hubbel plugs and Square D breakers.
If you're making the investiment in an 8" jointer, with a 2 HP motor, it really should be on its own dedicated branch. I think if you're spending that kind of serious money, it makes no sense to jury-rig something to a laundry outlet, etc. A 2 HP induction motor is a hefty thing, and will perform at its best only when given adequate power.
If the jointer doesn't come with a plug installed, the manual should specify what size to install. My dust collector has a 2 HP 220V motor, and specifies a NEMA 6-15 plug (15A, 220V w. ground).
That dictates the size of the outlet. For a dedicated branch, the branch circuit rating will match the outlet size; 15A in this case.
Even the the motor may have thermal overload protection, the cord from the plug to the motor is unfused, and any fault in the cord must be dealt with by the branch circuit breaker. It's just good engineering practice to keep the fault-current protection device rating no larger than necessary. For example, that's why you're not allowed to put a 15A outlet on a 50A branch: the cord and the equipment plugged into it would potentially experience a much higher level of fault current than what they are designed to handle. In other countries uch as the UK they have a different philosophy, but they put fuses in the plugs themselves to protect the downstream devices.
But if you want to install 12G or even 10G wire, go right ahead. The motor will love it: voltage drop will be minimized, especially helpful during startup. There's no reason why you can't use a 15A breaker and a quality 15A outlet with 10G wire. Ultra-cheap 110V 15A outlets don't except that gauge, but a commercial or industrial 220V outlet should.
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