So I am no electrician by a long shot, about the most I do is put receptacles in the walls and put new cords into electric tools. My issue is when I start my chop saw it trips the 20 amp breaker. All 3 of my chop saws (2 makitas and 1 dewalt) are all 15 amp saws. I realize the starting load is probably bigger than the running load but its a real pain. It wont trip it every time but probably 40 percent of the time which gets real old walking back to the breaker box that much. The same thing happened at my old shop as well. The 15 amp saws were always tripping the 20 amp breaker there. Would putting a 30 amp breaker fix the problem? I have no other tools besides the chop saws that draw more than 15 amps that are not 220 volt so the biggest amperage drawing tool I have that could even plug into the receptacle is the saws. What would be the thing to do to remedy this?
Saws keep tripping breaker
- Thread starter bigcreek
- Start date
Aceman
Well-known member
Try replacing the breaker first. With an identical one. Don't use a 30. What kind of panel is it?
Try plugging your chopsaw into a recep near the panel and definitely not on a long extension cord. When volts go down, amps go up.
If the problem persists, you may have other issues.
Try plugging your chopsaw into a recep near the panel and definitely not on a long extension cord. When volts go down, amps go up.
If the problem persists, you may have other issues.
remauto1187
Member
You never put a Breaker in that is bigger than what the wiring it feeds. 20A-12ga 15A-14ga etc. Breakers are there to protect the wiring and your walls from fire.
Check all of your connections (neutral and hots) at the breaker panel and at the outlets for all circuits that keep tripping. A loose connection will cause exactly what you are experiencing. A bad breaker will also do this.
Do your lights dim when you fire up a tool with a motor? Is wiring in walls alum or copper?
Check all of your connections (neutral and hots) at the breaker panel and at the outlets for all circuits that keep tripping. A loose connection will cause exactly what you are experiencing. A bad breaker will also do this.
Do your lights dim when you fire up a tool with a motor? Is wiring in walls alum or copper?
wyliesdiesels
Well-known member
How long is the feed to the breaker panel?
What size panel?
What voltage are you getting at the panel?
Are u using extension cords?
What size panel?
What voltage are you getting at the panel?
Are u using extension cords?
Thanks for the replies. Wiring is 12 gauge copper. Saw is on a 20' or 30' ext. cord. Ill try it w/o the extension cord. Except the extension cord is kind of a necessity. Would it make a difference at all if I used a 10 gauge extension cord instead of a 12 gauge cord? Lights do not dim. Ill change out the breaker and check to make sure all connections are tight. I have been using my Ridgid tristand pipe threader a ton lately and its never tripped the breaker. Id think it would have a heavier draw than a 14" chop saw but maybe not? Thank you.
I am getting 100 amps at the panel and yes I am using extension cords. I am probably about 20 or 30 feet from the panel.
wyliesdiesels
Well-known member
i didnt ask about the amperage.
I asked about the voltage.
U will need a meter to measure voltage.
Try using a shorter extension cord and/or a beefier one. hat gauge is the cord youre using?
As aceman pointed out, if voltage goes down due to longer distance the amps will go up.
I don't know the voltage but I do have a meter I can check it with. I was using a 12 gauge cord but will try a 10 gauge and see what that does. thank you.
matt_i
Well-known member
The one in our plant shop does this also. We just live with it. Personally I'd choose to cut metal on any other tool than that.
Since this issue only on startup, your saw is probably pulling way too much current for that instant and putting you next to or into the trip curve of the cb. Probably next to since it only happens 40% of time.
As said above try changing out the cb with a new 20A.
Check all your connections as a good measure.
Measure your voltage. What is is it? The higher it is, the higher the inrush current. EG - 115vac will have less inrush than 125vac.
Go purchase a 50' 14 gauge ext cord. You don't even need to unwrap it. just plug it in between your saw and existing extension cord.
Start the saw with the new cord installed. if it clears your problem, then the extra resistance in series with the motor has moved you slightly away from the breaker trip curve. (Problem is these residential grade cb's dont have adjustable time curves. Putting a 30A in would move you onto another curve but it creates a code/safety violation. so don't do that.)
This is a balancing act here. If this extra resistance is too much while doing a long cut, you may see the motor now pulling higher continuous current and put you into a different location on the trip curve and still trip - just much later in time.
Bigger gauge cords, closer to panel, etc. make the issue worse for startup trip conditions.
Also make sure you saw has good bearings and isn't dragging *** trying to overcome the friction load from them. Does it easily freewheel?
All the saws are good saws. They freewheel. So from what I am reading in your post mm08822 a smaller cord like 14 gauge would be better for preventing tripping than a bigger cord like 12 or 10 gauge? And a longer cord as well? Sheesh everything that makes sense to me just went out the window. Id have thought a bigger, shorter cord would help but like I said Im no electrician! 
LOL..... I think you needed exorcisms from a reputable priest / priestess like my VW that have the weirdest electrical problems......... Or a new breaker. I am only on 50AMP sub, and 100+ft extension, don't have this issue. can you try a different plug on a different breaker?
penright
ALLIANCE MEMBER
All the saws are good saws. They freewheel. So from what I am reading in your post mm08822 a smaller cord like 14 gauge would be better for preventing tripping than a bigger cord like 12 or 10 gauge? And a longer cord as well? Sheesh everything that makes sense to me just went out the window. Id have thought a bigger, shorter cord would help but like I said Im no electrician!
I think @mm08822 was using the smaller/longer cord as troubleshooting. If breaker trip off current, then anything you can do to limit current will keep it from tripping. Smaller/longer cord will add more resistance, lowering that initial current. If a motor uses back EMF for current limiting, then it has to start spinning to generate it. That's why it almost a dead short when I motor starts. Dead short, lots of current. He did mention you would not want to run it for a long time. If you limit the current, and the motor under load slows down, then design back EMF goes down and current goes up, motor melts down so to speak. I don't think any one was saying smaller/longer is better, but just in case someone else is reading this, just wanted to be clear.
Unless someone can explain why, bigger/shorter electrical cords are always better, especially on motors.
20 or 30 feet on #12, with a 20amp breaker doesn't seem too much. Something is broke. It's hard to believe that 3 saws would have the same issue.
Did I miss it, did you try it on a different circuit? Maybe wait till the wife goes to the store and try it on one of the house circuits?
zmaxmotorsports
Well-known member
Are you letting the saw get up to speed before shoving it into what ever you're cutting?
Iam saying that a smaller cord is better in this case because inrush current is too close to trip curve. This is a way to simply add a very small amount of additional resistance to lower inrush current.
On a normal motor circuit the breaker can be 250% of fla. This however is a convenie ce outlet and breakers cant be randomly changed for higher.
On a motor circuit you do design for max voltage and current so you can get full output of motor and maybe a little extra when you get into the service factor area for short periods. This is where you dont want any low voltage at full load so larger wire, shorter runs is desired.
matt_i
Well-known member
I don't think its solveable without a 30A breaker wired to #10awg but still hooked to the 5-15 outlet...the inrush is too great. Although I've seen a guy bury a blade to the point in a piece of solid tool steel that he work-hardened and this tripped the 20A breaker in steady state. The motor is capable of drawing more than 20A, especially when you consider the 'back emf' on the startup...
AntonLargiader
Well-known member
How long does it take to trip? Does it happen instantly (magnetic trip) or after some time (thermal trip)?
I had that issue with my ancient Delta 15A chop saw; it tripped after about a second and I think going away from an extension cord helped me.
I had that issue with my ancient Delta 15A chop saw; it tripped after about a second and I think going away from an extension cord helped me.
wyliesdiesels
Well-known member
U cant put a 5-15r on a 30a breaker...
rsanter
Well-known member
This.....what else is on the same circuit?
I like to have a dedicated circuit for the garage.
Where is your main panel? If it is on the side of the garage then add a single breaker and wire it to a single plug opposite the panel on the inside of the garage
Bob
sberry
Banned
There may be an exception for this and small welders. increasing the size of the wire makes it worse. A dedicated circuit is needed where the breaker can be sized up, use a 12 on a 30. I carry a 14 cord 50 ft for my small air comp for this, it it automatic and want it the same size as the cord on the machine, I have used a lot of these saws on 25 ft of 16 due to this.
Attachments
sberry
Banned
Back in the day had old service, old transformer with lots of long wire on it and never a problem. When I upgrade, big fat wire, new ****** it became an issue especially on a circuit 3 ft from the panel.
The only exception permitted in 210.21 b3 is for welders and electric discharge lighting. Otherwise no upsizing permitted for general convenience recepts.
So 14 cord 50 ft is the only choice unless you hardwire it to become a dedicated motor ckt.
sberry
Banned
It wouldn't be a general convenience recept.
Interesting stuff thanks a lot for the replies everyone. Ill try this stuff out and see what happens. Had no idea a smaller cord could be my salvation. Ill be over there on Wednesday and can try it out then. Thank you!
most likely you got other loads on the same circuit. I tripped my breaker a couple of times with a miter saw. turned it it was the extra freezer on the same circuit. moved outlets and no more problems. i can run a shop vac and mitersaw on the same circuit as long as i stagger startup. try to turn them on at the same time and it trips.
sberry
Banned
This is a routine problem with these, even without "other" stuff on the circuit. Especially where service is good and strong, it delivers so much so fast.
Awesome, thank you.
Well problem is solved. As long as I use a 14 gauge 50 foot cord to the saw I have no problems as long as it is not plugged into the receptacle closest to the breaker box. That receptacle is only a few feet away from the box and still trips the breaker but the rest of the receptacles do not trip the breaker with that 14 gauge cord. Thank you everyone for the education!