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Can you plug a 220v table saw into a 60A plug/breaker

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Forum topic by rlrobinhood posted 03-28-2011 05:16 AM 4366 views 0 times favorited 19 replies Add to Favorites Watch
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rlrobinhood

80 posts in 2107 days


03-28-2011 05:16 AM

Hi all,

In my shop, I have a 220 circuit that has only one outlet on it (completely normal, I know). I believe this was originally used for a welder and the breaker on the circuit is a 60A. My question is can I plug my table saw into this? I know I can change out the breaker to a lower amperage, but hope to have a welder soon and want to be able to plug it into it as well without doing a bunch of switching around. Also, I don’t have any spaces left in my box.

Table saw is a old Craftsman (113) direct drive 12” saw. At 220v, the motor says it pulls 8.4A. Also, the motor on the saw has an overload reset button.

Thanks a million.

rlrobinhood


19 replies so far

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patron

13535 posts in 2802 days


#1 posted 03-28-2011 05:32 AM

at 60 amps
it will run the saw at 8.4 amps

but if there are any problems
it wont shut the breaker
before it fries the motor
or switch

just my guess here
bob will be along soon
and give you the facts

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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ajosephg

1878 posts in 3022 days


#2 posted 03-28-2011 05:42 AM

Yes. go ahead.

CB is to protect wiring, not appliance. Think about all the other circuit in your house that have minimal loads, for example a radio that maybe draws 1 amp in a 20 amp circuit.

Besides, most shop equipment have built in overload protection.

-- Joe

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TopamaxSurvivor

17654 posts in 3137 days


#3 posted 03-28-2011 05:46 AM

I’m still awake David ;-) It will run the saw, but it is not a very good idea to over fuse it by that much. If there is a short circuit, it will most likely burn something up before the circuit breaker trips. The reset button on the saw is for overload protection which is different than over current protection.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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patron

13535 posts in 2802 days


#4 posted 03-28-2011 05:46 AM

good point joe

nice to know these things

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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TopamaxSurvivor

17654 posts in 3137 days


#5 posted 03-28-2011 06:02 AM

I think circuit breakers are supposed to stop fires no matter where they hapen to be, inside the wall or out!!

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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ajosephg

1878 posts in 3022 days


#6 posted 03-28-2011 06:27 AM

Bob: What you’re saying makes sense, but carried to the extreme wouldn’t that require all electrical cords to have the same current capacity of the wiring in the walls?

Also, I’m not sure I agree or understand what you mean that overload protection is different that over current protection. If a motor gets overloaded, it will draw more current and kick out what ever circuit/overload protection has the lowest rating. If a short occurs (downstream from the outlet), the same thing happens, big time current draw, again kicking out one or both circuit breakers. If the short occurs between the outlet and the tool, then the only protection is the CB in the panel. That is why it behooves us users to keep an eye on the condition of of drop cords, and not to overload them.

-- Joe

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David Grimes

2078 posts in 2101 days


#7 posted 03-28-2011 06:40 AM

The breaker should match the gauge of the wiring… period.

Your 60 amp breaker 240 volt single phase circuit should have 6-3 with ground copper wire if memory serves correctly. If aluminum, 4 gauge(or rip it out and replace with copper). I would not use aluminum except for very large service entrance with the terminal end slathered with no-lox.

If you have a dead short, it will trip the breaker… again, as long as the gauge of the wiring is sized to the amperage rating of the breaker.

If you have any problems internal to the saw, then the thermal overload should stop it far short of frying or fire, since all of the scenarios (like bearing(s) starting to seize, rotor/stator problems, etc. would generate heat as a byproduct of the failure. Other failure modes would result in the opposite: the internal device would have a break in its circuit and nothing will take place. It will be drawing no current at all.

You could change the 60 to an arc fault breaker for more sensitivity to other than amperage draw if you’re a doubting thomas and then rest the peaceful sleep of the blissfully ignorant.

YES ! You can plug the saw in there as it is now with no worries.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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crank49

3980 posts in 2432 days


#8 posted 03-28-2011 07:17 AM

10 ga wire is only good for 30 amps; don’t matter if it’s 10-3 10-4 or what ever.

But, back to the welder outlet, it’ll run the saw with no problem. If you really want to you could possibly replace the breaker with a smaller one, but then you can’t run a welder on the circuit till you put the bigger breaker back in. Don’t see a really good reason to do this.

Another option might be to put a sub panel in and use the 60 amp feed to power the panel. That’s what I did in my garage. I have a #6 ga 240 volt 3 wire feed going to a small (4 circuit) sub panel. The panel runs 2 circuits of 120 volt outlets, my 220 volt 2 hp air compressor and also has a welder outlet. I think maybe once in 30 years when I was welding at high power (1/2” plate, burning 5/32” rod) and the air compressor happened to start at the same time, I kicked out the 60 amp main feed, but otherwise, no problem.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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TopamaxSurvivor

17654 posts in 3137 days


#9 posted 03-28-2011 07:44 AM

Joe, et al, Over current protection, circuit breakers and fuses, protect the wiring and devices if there is a short circuit or other excessively high load on the wiring.

Overload protection protects the motor from running too hot because of physically overloading it or under voltage causing it damage. It is not a short circuit protection. It is a time delay protection to allow for starting. Most overloads are set too high to be of much value, IMO, but that alleviates nuisance tripping.

Manufacturers can do lots of things electricians cannot do. For small appliances and other devices normally connected to 15 or 20 amp household circuits, they use cords as small as 18 gauge but they cannot be longer than 6 feet. The code allows for making taps off circuits and feeders using smaller wire too. It is normally not an issue in the circuits we are normally using in our shops and houses.

The proper way to wire the saw with 8 amp load is to plug it into a circuit no larger than 20 amps. 15 would be better protection for it, but I am not 100 % certain what the code says about the difference between using a 15 or 20 amp circuit if it is not a dedicated circuit for the saw.

If it were my saw, I would not run it on a 60 amp circuit. If there is a problem, it becomes a fire hazard too easily.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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Grandpa

3256 posts in 2137 days


#10 posted 03-29-2011 06:08 AM

I believe David Grimes pretty well read the code to you in his statement above. I also think if you change to a 20 amp circuit breaker you will find that the wire will not go under the screw on the breaker. If you trim some of it off you no longer have a # 6 wire rated for 60A.

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rlrobinhood

80 posts in 2107 days


#11 posted 03-29-2011 06:20 AM

Wow, lots of comments here. Thank you very much. I’ve always been a “play it safe” kind of person and “better safe than sorry.” So, with this being said I think I’d like to protect down to a lower amperage. Due to the fact that I want to be able to run a welder and a saw from the same outlet, is there a way to make a short inline protection pigtail? Maybe a pigtail with a small breaker box or maybe one that will take a fuse?

Fuse…. with 220v, how do they fuse it? Is there a fuse on each hot leg? If so, what would happen if the table saw received power on only one leg?

Any thoughts? Thanks again.

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TopamaxSurvivor

17654 posts in 3137 days


#12 posted 03-29-2011 06:20 AM

Yes, but the thermal protection in the saw is a motor overload, not a short circuit or over current protection. These are two different animals, it is like mixing up apples and oranges. I know it is not easy for the layman to understand the difference, not sure how to simplify it any more.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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ajosephg

1878 posts in 3022 days


#13 posted 03-29-2011 06:42 AM

IMHO Small motors may or may not have the protection Topamax is talking about. I don’t think my saw does. Its protection amounts to a circuit breaker (with a red button sticking out) in the capacitor housing.

Here’s a link to back up what I said. http://www.kilowattclassroom.com/Archive/MotorOL.pdf

robinhood – each leg of a 220 volt line is protected. A 220 volt circuit breaker will open both lines if a fault occurs, so your question about what would happen if the saw receives power on only one leg is mute. However, if it did receive power on only one leg, nothing would happen, it wouldn’t run. No current runs through the common or ground line in a 220 volt motor.

I guess if you want to be super safe you could wire in a small breaker box with a pigtail, but I’m not sure if that meets the NEC code, and I don’t have access to a code book.

-- Joe

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bubinga

861 posts in 2129 days


#14 posted 03-29-2011 06:46 AM

If you are running A one amp device on a single circuit with a 20 amp breaker in your house
Do you change it to a one amp breaker ?
Answer—NO
The breaker is to protect the wire from over heating
If you running something that is drawing 8 to 10 amps, and the wire is rated at 60 amps your good to GO If you get a short,the breaker will pop just over 60 amps to protect the wire from catching fire,but it wont protect the motor,HENCE, overload protection on the motor,that’s why overload protection is there
The best thing to give piece of mind, and best protection is put in in sub panel,and it’s really pretty easy

-- E J ------- Always Keep a Firm Grip on Your Tool

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TopamaxSurvivor

17654 posts in 3137 days


#15 posted 03-29-2011 07:31 AM

rlrobinhood You could run the cord into a small box that holds one circuit breaker or a small fusible disconnect, then run your saw outlet from that.

The bottom line is preventing fires and catastrophic failures. There are many sources of these in electrical systems. Erring on the side of caution with proper fusing for the motor is a wise choice. If the motor should ever fail, it will be quite a sight to behold on a 60 amp breaker unless your panel is a Sq D or Cutler Hammer.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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