220 electrical question

[turkeyrun]

I see. All of these years studying wiring and I've never heard of that being necessary. What happens when you plug in a blender or something that draws only a couple amps on a 20amp circuit?

I guess because I'm always making sure the circuit and wire are large enough, rarely having to worry about too large.

What is "normally" taught is having the circuit capacity needed for to prevent overload and fire protection.

Too much circuit isn't discussed, but can be a problem

IMHO, a welder should be on a dedicated circuit because of the high Amp draw. Not on a GF, welding IS a fault, by nature.

One solution would be to use a short "extension" cord, with a GFCI, for use on other tools.

 

[ConstitutionCowboy]

Don't know if it has been said yet, but the breakers are there to protect the wiring in the house (garage) and not what is plugged into the circuit. As long as the wiring is big enough to service that which is plugged into it and the circuit breaker is the proper size to protect the wiring, it doesn't matter how small the current draw is for the device being plugged into it.

Make sure, of course, the voltage is the same as for the unit being plugged into it. Don't plug a 120 volt thing into a 220 volt circuit. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZT!!!

Woody

 

[KOPBET]

…it doesn't matter how small the current draw is for the device being plugged into it.

That’s what my wife keeps telling me.

 

[Ahall]

Take a closer look
The center plug is 30 A, 125 V, not 220 on an RV system.

This is probably not the right approach to the issue.

 

[Ahall]

The OP asked about circuit protection for a 5 hp, 220v 17a table saw.
Woodworking machines in that power class usually have motor starting circuits with electronic relays and overload protection engineered into them when they left the factory. Smaller motors may have overcurrent protection engineered in as well.

Before advising the OP to spend time and money on rewiring the house or building electronic devices, it would be prudent to review the electrical gear on the saw.

He may have everything needed for electrical safety and to protect the machine without any modification beyond a new plug.

If the original starting circuits have been altered or removed, that's another issue.
Some of the thoughts in this thread are well meaning, but not quite on target.
The devices used to protect the equipment should be appropriate for the application. The circuit protection for motors typically acts like a resettable slow blow fuse. It tolerates the very high starting current for a brief period, but long exposure to moderate overcurrent trips it. The average breaker is not engineered to behave that way.

I, for one want to see what's on the saw, and stop guessing.

 

[trekrok]

Ok, a revision. The tag on the saw motor I can only partially read. I said 17amp because I thought the tag said 34 amp at 110. But I think it's 24, so 12 amp at 220v is likely what I'm dealing with. It's a 2hp motor off a compressor so that would make more sense based on comments above re hp to amps.

My main concern here was just about what if something jammed, shorted out in the motor etc. would a breaker pop before sparks fly, if I just plugged it into the welder receptacle.

 

[Nate08chevy]

Ok, a revision. The tag on the saw motor I can only partially read. I said 17amp because I thought the tag said 34 amp at 110. But I think it's 24, so 12 amp at 220v is likely what I'm dealing with. It's a 2hp motor off a compressor so that would make more sense based on comments above re hp to amps.

My main concern here was just about what if something jammed, shorted out in the motor etc. would a breaker pop before sparks fly, if I just plugged it into the welder receptacle.

No. The breaker is rated too high to safely trip for the saw. Protection at the device can and does fail. Safety in redundancy. At a minimum swap breakers to a 20

 

[ConstitutionCowboy]

That’s what my wife keeps telling me.

Must be love!

Woody

 

[KOPBET]

If it were me and I was that concerned about it, I would convert an existing garage 120v recep to 240v 3 wire recep, mark both ends of the white wire as black, change the single pole breaker to a double pole 20A breaker (assuming I had room in the panel and the wire was #12.) Just my opinion which is most always wrong. Just ask her.

 

[montesa]

If it were me and I was that concerned about it, I would convert an existing garage 120v recep to 240v 3 wire recep, mark both ends of the white wire as black, change the single pole breaker to a double pole 20A breaker (assuming I had room in the panel and the wire was #12.) Just my opinion which is most always wrong. Just ask her.

That would work but would only be 20 amps due to 12 ga wire right?