OK New Recruit here so this probably sounds funny to you old timers here but I’m putting two 220V circuits in my shop. I figure to put three outlets on each circuit (probably never use more than one at a time). Now I know how to wire the circuit into the aux ckt brkr box but I don’t know what outlets to use (what do they look like?). All of the machines I have now are 110V but I am getting a 220v table saw soon and maybe more 220V machines later on. What kind of outlet plugs should I use? (Hope you’re not laughing already)
Thanks
Replies
you should probably just have the wires ran to where you want them and when you get your tablesaw see what kind of plug it has (if any) and buy your outlet to match, alot of tablesaw's do not come with a power cord just for that reason. You can also put whatever outlet you choose and then change your power cord from your equiptment. hope this helps. rb
The 220V outlets all look different depending on the amperage of thr the tool. A 220V 15A oullet will look different than a 220V 30A oulet. Your best bet is to run the wire and wait till your tool shows up, that way you can match the power cord from the tool to the right outlet. Just make sure you run big enough wire for the tool you want to use. A 2HP saw will use smaller wire than a 5HP saw.
Each tool could possibly use a different amperage of 220 volt. I have ####30 amp 220 volt circuit that I use for a 3hp cabinet saw. Recently I purchased an 8" jointer with a 2 hp motor. My original plan was to simply extend the line that I have for my cabinet saw to supply 2 outlets, since I will only use one at tool at a time. When I contacted the jointer maker they said I should only use a 15 amp 220 line for the jointer to ensure the motor will be properly protected. All 220 circuits must not be created equal.
Thanks to all for the quick responses. If i were to plan on using 220V for Tablesaw (3HP), Bandsaw and Dust collection wouldn't 20A be ample?
Again Thanks!Norm (never been on TV)
I use a 30 amp 220 for my 3hp cabinet saw (Jet). On Friday I called the manufacturer and asked if I could downgrade it to a 20 amp to see if I could get it more inline with the Jointer. Their answer was that I had to keep the circuit at 30 amp for the TS. I would suggest you check with the manufacturer to be sure.
BSzydlo,
You are misunderstanding the needs of a fused (circuit breaker) line to an electric device.
If you have a properly designed 30 amp circuit supplying a 3 hp saw, that means the wire guage is sufficient to carry the current the saw needs and that the breakers are designed to stop increased current flow, sufficient to damage the wires, (thereby starting a fire) should a short occur in the motor or anywhere else in the circuit.
The breakers are there to protect the wiring, not the motor.
Such a circuit is perfectly suited to supply a motor of lesser current-drawing capacity, such as a 2 hp jointer. The wiring is never taxed by the 2 hp motor. The fact that the wiring is capable of handling 30 amps means nothing to the 15 amp motor. It will simply draw 15 amps under all normal operating conditions.
Should the 15 amp motor develop a short, or if a short develops somewhere in the circuit, (in which case much more than 30 amps would flow through the wiring), the breakers will open, saving the wiring and your house.
Of course, you could use smaller breakers on wiring designed to supply a 3 hp motor, but being used only for a 2 hp motor. But breakers are normally selected for the current-carrying capacity of the wiring, not the devices attached to the wiring.
Rich
You're restating what an earlier poster said, and the open question is, can you find support for that position in the NEC?My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Rich, here is a copy of the email from the manufacturer "The full load amps of the 2 hp 1 phase 8" jointer motor at 220 volts is 11 amps. A 30 amp breaker is too large and will not protect the motor from overload. A 15 amp 220 volt breaker would be the correct size. The wire size is fine."
Thanks, Bill
Bill, and John D,
I stand by my previous post. Breakers in building wiring circuits are not there to protect motors from overload. Overload protection is a function of quick-acting cuircuits at the motor and is the duty of the motor manufacturer. Such protection can be electronic or mechanical, or both.
It is acceptable practice (because it is safe) to run a device from wiring rated and fused above the device's current needs or capacity.
The sole purpose of fusing (breakers) in building circuits is to prevent current overload, therefore fires, in the wiring itself.
Bill, that manufacturer's advice is self-serving and misleading.
Rich
Other knowledgeable people (which does not include me, I'm trying to learn the truth of this) don't agree with you, and if you look back, they've supported their position with information from the NEC.
If a manufacturer tells me I have to have a 15A breaker, I'll be hesitant to put it on a 30A circuit on your say-so without further analysis or support, given the seemingly compelling arguments put forth above. Some of the logic that precedes you makes sense.
For example: If the manufacturer has, say, 12g wire in the machine because it's only supposed to draw 20A, but he knows there are certain faults (stalls, partial shorts) that can cause it to draw more, he has two options. He can put OCP in the device and use it to limit current to an amount his machine can handle, or require you to add it externally. It does make logical sense that a device is built to handle only a certain amount of current, as a post above points out that common lighting equipment can handle 15A of current without breaking down though not many fixtures really use 1650 watts (110v * 15A) intentionally.
I, too, have always heard that the OCP is to protect the wiring and receptacles, but I can't find a good authority for it. And I can't refute the logic of the poster above. Can you do either?My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
The sole purpose of fusing (breakers) in building circuits is to prevent current overload, therefore fires, in the wiring itself.
Please cite the specifics paragraph(s) in the National Electrical Code where it says that.
I can't find them. In fact, I can find several that say just the opposite.
While it is true that the NEC says that motors over 1 HP cannot use the branch circuit OCPD for overload protection, that does not mean that your statement is true in the general case. Even in the case of a motor branch circuit, where overcurrent protection is provided by separate devices, there is a maximum allowable size for the branch circuit sohrt circuit protection device, as defined in Part D of Article 430.
Ok here's an example of the error that your position takes.
I have a tablesaw with a 15amp motor and a 15amp breaker built into the saw. I plug it into a 30amp circuit. If the motor stalls it trips yhe saw's breaker , that works. But if a fray develops on the cord and starts shorting to ground it could draw more amps than the 14ga cord canhandle, overheat the cord and cause a fire. The saw's breaker will not trip because the draw is befor the breaker.
That is why you should size the wireing, outlet and breaker to the equipment to be plugged into it.
Jack
So I take it that in your shop the desk lamp with the 16ga cord on it is plugged into a receptacle protected by a 1 amp breaker. You must have service panels cascading down the walls to make room for all those itty bitty breakers to protect the cord that came on all those low current draw goodies.
Since the house is on fire let us warm ourselves. ~Italian Proverb
No, the lamp and cord is UL listed for a 20 amps outlet, just because it only draws 1 amp doesnt mean it is designed to be only pluged into a 1 amp circuit, but I certainly don't have it pluged into a 50 amp outlet.
Jack
It seems pretty clear that the NEC and logic support sizing the breaker to both the wires and the attached device. It's also a long-held belief of many that the OCP is for the wiring, and I've heard it from many people, including electricians, not just here.
I think the only time you'd see an actual difference in performance is if you had the situation you described, where a device faulted and drew more than it ought to (to the point of melting something, starting a fire) but still less than the attached breaker. A dead short wouldn't do it, and you'd probably have to stretch quite a bit to find a situation where you'd really have a difference.
But barring further evidence, I think it's safe to conclude that best practice is to size the wiring for the largest load you think you might use with this or another device (to avoid pulling again), and size the breaker to the device.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
"But barring further evidence, I think it's safe to conclude that best practice is to size the wiring for the largest load you think you might use with this or another device (to avoid pulling again), and size the breaker to the device"
Within reason this will work. But if you think you may want to use this circuit for a welder later and need a 60amp service and you run the wires for that you would have a tough time attaching that big a wire to a 30 amp outlet that you need now, and I think it would be very poor practice to chang the plu on a 30amp device to a 60amp plug.
Jack
Edited 6/1/2006 1:44 am ET by JLMCDANIEL
You say within reason and then proceed to give a totally unreasonable example. Put down the joint and turn out the shop lights, there's nobody home .
Since the house is on fire let us warm ourselves. ~Italian Proverb
Ok, then run 10ga 3 cond plus ground to every outlet in you shop because someday you may want to plug somthing bigger into it and don't want to have to make anoter pull.
By the way it wasn't an unreasonable example, I just had to pull new wires for a 60 amp outlet to replace a 30 amp outlet when I replace my wire welder with a stck welder.
Jack
Edited 6/1/2006 12:25 am ET by JLMCDANIEL
Where did the 230 amps to 60 amps come from? By the way thats exactly what I did in my shop. I do hate pulling wire through conduit.
Since the house is on fire let us warm ourselves. ~Italian Proverb
Sorry about that I ment 30 amp device but i mistyped (fat finger syndrom), have edit message to make correction.
Jack
Edited 6/1/2006 1:47 am ET by JLMCDANIEL
But if you think you may want to use this circuit for a welder later and need a 60amp service and you run the wires for that you would have a tough time attaching that big a wire to a 30 amp outlet that you need now...
Not only that, it would be a violation of the NEC:
210.21 Outlet Devices. (B) Receptacles.(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.(3) Receptacle Ratings. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or where larger than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.
So no, you can't put a 30A receptacle on a 60A circuit.
What according to the NEC determines the capacity of the branch circuit, the wire used or the breaker that limits the current available?
Since the house is on fire let us warm ourselves. ~Italian Proverb
Barry,
I didn't say put a 30amp outlet on a 60amp circuit. The statement was made to use as big a wire as you may want to have the circuit in the future and an outlet and breaker for the amperage you need now. Which would mean wires big enough for 60amp (for future use) and a 30 amp breaker and outlet for the 30 amps that I need now.
Jack
I really have no interest in welding or any heavy mechanical work, just a plain little old wordworking shop for an old retired preacher.I will talk it over with an experienced electrician though.
ThanksNorm (never been on TV)
Your logic escapes me. 20 times it's rated current is ok but twice the rating on his saw is not? UL buyoff or not 20 amps through your desklamp cord will make a nice fire and the breaker is not going to prevent it.
Since the house is on fire let us warm ourselves. ~Italian Proverb
You could use 12ga wires and ceramic lamp socket and the device would be rated for 20amps but if you put a 100wat lamp in the socket it would only draw about .9 amps, ther is a differance between rating and draw.
Jack
Obviously....but he was talking about protecting the device wiring from a fault, not it's normal current draw.
Since the house is on fire let us warm ourselves. ~Italian Proverb
>
Your logic escapes me. 20 times it's rated current is ok but twice the rating on his saw is not? UL buyoff or not 20 amps through your desklamp cord will make a nice fire and the breaker is not going to prevent it.
**Apologies in advance but this may be wordy and specific to NA:
What Jack was trying to say, I think, is that the lamp, as a general purpose residential appliance, is capable of surviving a short to 15A. (I'll use the 15A number because ALL residential appliances in THIS country are only rated to 15A.) Doesn't matter what wattage bulb you use in it for the purpose of this discussion. The reason you see a rating of 60W or 100W on a lamp is to limit heat generated by the bulb itself. That number is not a limitation of the appliance's wiring.
There are so many appliances out there that the codes in question call for all low power appliances to have suitable circuitry to safely handle the 120V potential (prevent tip-tip arcing and electrocution) and the 15A max (short circuit) current (prevent fires). Believe it or not, 16ga wire will safely handle 15A in most cases. *Most* people use 16ga extension cords for portable power equipment all the time. (Personally, I use 12ga cords but I'm admittedly paranoid. That's because I've done all kinds of experiments to test these limits. Electronics was my childhood hobby. The only time people generally use heavier guage than required is on hifi speakers... thanks to greedy "Monster" marketing.)
The point is, because it would be impractical for the branch wiring and breakers to accomodate all low power devices, the general circuits (CEC and probably NEC) are 15A and all devices are designed to be compliant (certified safe by UL or CSA) with that. In fact, as I've pointed out, CEC does not allow residential lighting on anything above 15A service. Btw, that's why I think the 20A receptacle as an alt for the 15A duplex over the kitchen counter is a mistake that CEC will eventually correct.
Service to all larger appliances *should* be sized appropriately. In the CEC, this is implicit if not explicit. Your stationary tools discussed here, as well as dryers, stoves, welders, etcetera, should be provided for separately. As I've said, the ultimate purpose of the code is to prevent house fires. The codes are just a compilation of words and cannot cover every case. Understanding the *spirit* of the code, which is just trying to prevent house fires, means understanding *why* those words and rules are there. You can't really learn about electricity from those rules. Most electricians (hopefully not too wide a brush) learn those rules and don't have a deeper understanding of electricity than what they observe within their field. To understand it, you have to study electricity, not a rulebook, and play with it and its limits. Since most people won't do that, there are rules to follow which attempt to limit dangerous practises. They're still not fool-proof. When an extension cord mfgr says "this device is for temporary use" and the code says "extension cords are for temporary use", how many people listen? That's why there are laws and insurance companies that say: follow the code. And if you know better, strategically exceed the code. Your family may depend on it. The code here says you can have 12 outlets (plugs or lighting fixtures) on one branch circuit and run 14ga wire up to 100ft (approx?). How many people know that 100 clock radios are OK on one circuit while a vacuum and a dehumidifier are NOT OK on one circuit? How many know it would be unsafe to run a 12000 BTU window AC on a long stretch of 14ga shared circuit?
That's why I wired my shop with separate 15A and (mostly) 20A breakers and separate 12ga wire to each outlet. I can change the breaker later. If I need a larger service later (my largest motors now are only 1.5HP), I'll run another branch from the sub. Outlets abound on every wall, not just at 6ft intervals for walls at least that size as the codes says. I even have 20A circuitS for my treadmill and window AC.
Accidentally plugged my dust collector (1.5HP) into a 15A outlet recently and tripped the breaker with the flip of the switch. OK, because it draws much more than 15A at startup. Back to the T-slot outlet where it belongs. That might not have been noticed on a longer run of 14ga branch to a 15A outlet because of the voltage drop but it doesn't make it a more safe practise. In this case, when code says to size a circuit to 25% above the expected load, they are *not* taking a single motor load into consideration, believe me or not. That limit of applying only loading 80% of a circuits capacity is for more of a resistive load and usually multiple devices make up such a load. A single motor that draws that much static current will draw more dynamically and you better understand enough about electricity to *not* have that serviced by a 15A branch with other loads on other outlets.
Just my 3.47 cents (inflation is rampant this year).
Andy
These discussions tend to devolve into what the NEC means, but I think the fundamental problem is woodworking machinery manufacturers who suggest that the circuit breaker be used in lieu of a starter with overcurrent protection. The obvious driver is low sticker price. Sure it's theoretically possible, but to me it makes no sense to be talkng about resizing your circuit breaker to protect a particular motor. Pete
Edited 5/31/2006 11:16 pm ET by PeteBradley
Amen
Since the house is on fire let us warm ourselves. ~Italian Proverb
Taunton published a book entitled "Wiring a House" which contains some data that you need. There has been a series of booklets entitled "Wiring Simplified" which I find more complete yet easy to understand. The latter publication is brought up-to-date regularly. I would suggest looking for them at your library before purchasing either one of them. You should probably use 20-A or 30-A receptacles, depending on your wire size. A 15-A plug can be inserted into them, but not the other way around. Receptacles have their voltage & current ratings printed on them also. Making a study of them at a hardware store can be educational.
Whether your work must be inspected or not, it is wise to follow the electrical codes.
Cadiddlehopper
Thanks Caddiddlehopper. I'm off to the Librrary now --opps, since it's a holiday weekend I should probable wait until Tuesday!
Norm (never been on TV)
I would probably just head to my local Electrical supplier, Those counter fellas will set up properly in no time.Work Safe, Count to 10 when your done for the day !!
Bruce S.
Thanks to all of you for the good advice. I now see there is more to this than I originally thought. Bruce I think you were right, the best thing I can do at this point is go to an electrical supply shop for the right result for my situation.
Again to all I say thanks!Norm (never been on TV)
No offense, but successful electricians have more freedom and are a lot better paid than electrical supply clerks. You'll be pretty lucky if you get one that's a qualified electrician, and rightly so.
You need to either hire a proper electrician (on a consulting basis, if you wish to do the work yourself) or educate yourself with books etc., and also check with your city inspector once you've decided what you're going to do to have your plan checked.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
I can totally disagree with you on the counter clerks, The Electrical supply store that I go to have the best help I've seen. And are NEC experts, these guys are pros. Not Big Box Store clerks. The Owner and his Sons run the counter along with three helpers. And He makes sure that you will pass the Nit Picky Building inspector, and boy is our County Inspector a fussy guy. Our County codes Exceed NEC. No red tags on my shop when I built and wired it. You don't have to be in the IBEW to be a good Electrician.Work Safe, Count to 10 when your done for the day !!
Bruce S.
Hmm. Obviously my experience isn't universal. The Platt I shopped at did NOT have qualified people selling. Neither did the big box, but that won't surprise anyone... hopefully anyone relying on the clerk will go where you were smart enough to shop, not where I ended up. :)My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Here's what I would do in your case. Hire a good certified electrician and explain to him what you want. This might cost you a little now but might save a lot in the long run.
Be careful before putting multiple outlets on a single 220v circuit. There may be no problem doing it, but it might not be legal where you live. If you have a fire and you have wiring that's not to code, you could find an insurance claim denied. Or a subsequent owner of your house might just try to make you legally responsible if there's a fire.
So you should contact your city's building permit department. Find out what code is for your town (it does vary from place to place). Where I live, you cannot have more than one outlet on a 220v circuit, so each outlet has a run of wire that goes to its own circuit breaker. This may or may not be true where you live, so get your plan checked before you run the wire.
I suggest looking at the most powerful machine you might consider getting. For me, that was a 220v/21A, 5 HP table saw. That meant I wanted 30A (21A + 25%, 30A is the smallest that works) circuits, so I ran 10/2 (+ground) wire from the breaker to all five of the 220v outlets I put into my garage. For convenience, all my 220v equipment (jointer, bandsaw, table saw, space heater) uses the same NEMA 6-30 plug, so moving equipment around is easy.
If I had a machine that really needed to be limited to 15A on its circuit, I could still use the 10/2 I ran in the wire, just swap out the 30A breaker for a 15A breaker, but more likely I'd just use the 30A breaker. Do you use a 0.9A breaker to limit current to a 100w light?
Do you use a 0.9A breaker to limit current to a 100w light?
I'll address this one. No, you don't need to install a 0.9 breaker. That 100W light comes with a 15A plug, and a UL sticker. UL knows that a 15A receptacle will either be on a 15A or 20A circuit. The UL sticker means they've tested it to be safe when installed on a 15A or 20A circuit.
That same lamp many not have been safe if it was installed on a 50A circuit. Which is why the NEC doesn't allow you to put 15A receptacles on 50A circuits.
Assuming this is a residence in the USA, you won't have any 220V circuits. You can do 120V, or 240V.
As for the OP, it's best to consult a licensed electrician.
First of all the breaker's purpose is to protect the wireing not the device pluged into it. If you use 12 ga wire you use a 20 amp breaker, if you use 14 ga wire you use a 15 amp breaker, etc. If you use heavy enough wires you could use a 100amp breaker and you could plug a 100 wat lamp into it or a 5 hp table saw. The breakers purpose is to protect from over loading the wireing . You could plug a lamp UL listed for 15amp circuit into a 20 amp outlet, the plug would fit. If the lamp had a problem and drew 19 amps it would more than likely melt the insulation on the wireing on the lamp but the breaker wouldn't trip, but is the lamp had a problem and drew more than 20 amps the breaker would trip.
Jack
First of all the breaker's purpose is to protect the wireing not the device pluged into it. If you use 12 ga wire you use a 20 amp breaker, if you use 14 ga wire you use a 15 amp breaker, etc. If you use heavy enough wires you could use a 100amp breaker and you could plug a 100 wat lamp into it or a 5 hp table saw.
With all due respect, that is incorrect. It is stated many times on the internet, enough so that is is considered "common knowledge" by non-electrical professionals. I consider it the number #1 "internet myth" about the NEC.
The are, in fact, many section in the NEC where the branch circuit OverCurrent Protection Device (OCPD) provides protection for fixture or equipment wiring. For example, see 240-4, or 422-11. Can you state where in the NEC it says that the OCPD only protects the branch circuit wiring?
I come down hard on this because this thinking leads to dangerous beliefs, like the idea that you can plug a 100W lamp into a 100A branch. To the contrary, 210-21(b) is quite clear that a 15A receptacle can only be placed on a 15A or 20A branch, and a 20A receptacle can only be placed on a 20A branch. The whole point of this requirement is to avoid the type of "drinking from the fire hose" scenario you propose. A 100W lamp could never be engineered to be safe, if there existed the possibility that it could be hooked up to a 100A branch. A 20A branch is a different matter: the rated ampacity of 18 AWG lamp cord is 10A, according to Table 400-5(A). So it may get real warm when it has 19A going through it, but I doubt is would melt. In any case, UL has tested that situation as safe, so we can comfortably have such items in our homes.
[BTW, the case of the 5 HP table saw can sometimes be a special case. If is installed on a dedicated circuit that follows the rules in Article 430 for Motor Circuits, the branch circuit short circuit protection can sometimes be quite large, as large as 70A for a 5 HP single-phase motor. But still not quite as high as 100A. This is a special case in the NEC for dedicated motor circuits, where a separate motor overcurrent protection is also present. It doesn't apply to general purpose circuits.]
As I said, this seems to be a common misconception. There was a post here a few months ago where some guy swore up and down that it was perfectly permissible to install 20A receptacles on 50A circuits, because the "breaker only protects the circuit wiring, per NEC". He continued to believe this despite what the NEC says, and despite the master electricians over at Breaktime telling him he was all wet. Unfortunate, since it is a potentially dangerous belief.
Barryo,
I,m sorry if I gave the impression that it was OK to plug a 100wat light into a 100amp service, that was not my intent. The breaker is sized to the wireing and outlet. The wireing and outlet should be sized to the use.
Jack
The breaker is sized to the wireing and outlet. The wireing and outlet should be sized to the use.
Fair enough.
>First of all the breaker's purpose is to protect the wireing not the device pluged into it. If you use 12 ga wire you use a 20 amp breaker, if you use 14 ga wire you use a 15 amp breaker, etc. If you use heavy enough wires you could use a 100amp breaker and you could plug a 100 wat lamp into it or a 5 hp table saw. The breakers purpose is to protect from over loading the wireing . You could plug a lamp UL listed for 15amp circuit into a 20 amp outlet, the plug would fit. If the lamp had a problem and drew 19 amps it would more than likely melt the insulation on the wireing on the lamp but the breaker wouldn't trip, but is the lamp had a problem and drew more than 20 amps the breaker would trip.
---
The breakers purpose is to prevent a fire from burning down your house. You have to understand the reasons behind the electrical code, not just the exam questions a person must answer in order to become 'qualified'. For the reason you stated, it is not wise to plug a 15A fixture (for a 100W bulb for instance) into a 20A outlet. This is (mostly) not allowed by CEC. (Hopefully they will correct the 20A kitchen duplex outlet mistake.)
In the case of large appliances such as stoves, dryers, and stationary tools, the breakers purpose is *also* to protect the appliance, both from destruction and from causing a house fire. There would be no point in protecting the branch circuit wiring if its destroyed in a fire caused by a lamp cord.
I'm constantly amazed how people use electricity in their houses. 12 outlets on a 15A circuit (CEC; NEC too?) is too many in a modern house. Extension cords were meant to be used temporarily. Would you drive your car all year on its undersize spare? A 15A 120V motorized appliance should be used on a dedicated 20A circuit. Do you always fill your coffee cup to the brim and wait for it to spill?
I was disgusted to find out that outlets and lights in all three of my bathrooms were on the same circuit. Two hair dryers discovered that one in a hurry. *Just* following code is not good enough. So much for having a 'certified' electrician do your work. As with owning an automobile, you have to take responsibility for your house and understand how it works if you want it to be safe.
I wired my home shop with 15 outlets (mostly 20A) on separate circuits/breakers off a 100A sub with a quick disconnect. Lighting on a separate 15A from the main breaker. Overkill. Not for the paranoid (me.) Verbal diarhea? Maybe yes so I'll stop now. :)
Andy
When I took a class in electric wiring, I was informed that the official voltage was 115 or 230 volts even though it was actually 120 or 240 or whatever. That was some years ago and no, I cannot vouch for the accuracy.
tinkerer2,
The "official" nominal voltage for the USA, as defined in ANSI standard C84.1, is 120V line-to-neutral, or 240V line-to-line, for the usual type of single phase power one sees in a home. This can vary a bit, of course, but that's the target.
Motor nameplate voltages are either 115V or 230V. They are a bit lower to compensate for the expected votage drop between the Service Entrance, and the motor's input terminals. For example, a 230V motor is designed to work OK with a voltage from 207-253, which is close to what you'd get from a 240V supply, at the end of a branch circuit, with the -13%, +6% tolerance defined in C84.1.
Thanks BarryO, So 120 volts it is. One has a tendency to believe what you here the first time you hear it, especially if it comes from a teacher. Takes several negatives to conteract the first positive.
>If I had a machine that really needed to be limited to 15A on its circuit, >I could still use the 10/2 I ran in the wire, just swap out the 30A >breaker for a 15A breaker, but more likely I'd just use the 30A >breaker. Do you use a 0.9A breaker to limit current to a 100w light?
John, with due respect, that's not a fair analogy. It would be impractical to install breakers for smaller appliances such as a 100W light.
Also, the 100W light *bulb* cost $1. Its fixture is rated to withstand a short-circuit condition to 15A, not just 0.9 or 20 or 30A. A motor with a 15A rating stands a much better chance of surviving a stall if on a 15A breaker than if on a 30A breaker. It also costs a lot more and will stall more likely than a 100W light will. :)
FWIW, the CEC here does not allow residential lighting on a 20A circuit. I personally would not put a 15A outlet on a 20A breaker for the reasons outlined above. Choice of branch wiring is irrelevant as long as its minimum for the application (eg. 14ga for short runs of 15A with no bundling).
Andy
You and BarryO may well be right. If the manufacturer says to put a 20A breaker, that's probably the best thing to do.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Norm, I agree with John D and stopped reading after then.I believe that for this sort of application, if one is not suitably experienced, it is safer and cheaper in the long run to hire a Genuine Elecktrickery Dawg, so that you start off right. Observe what he does, then come back and read all the posts here.(;)
Test of on-line reply.
lwj
This forum post is now archived. Commenting has been disabled