220v 40 amp to 15amp

[Stevematt21]

Hey guys I'm building a new house, and the electrician just finished installing a 40amp 220v outlet in my garage...

I wanted to be sure I had enough power for any tool I might need...

Now what I am wondering is how do I convert the outlet to accept a 220v 15 amp table saw I would like to plug in..

What do I need to do in order to do that? The plugs are different I know that much..

Thanks!!

 

[gungatim]

a different plug.

 

[dw1]

and breaker, dont leave your 15 amp table saw on the 40 amp breaker.

 

[sberry]

It depends on the motor and the cord. If it is really 15A will have a 14 cord and a 30A is the max breaker.
I really don't understand a 40 to a recept for general. If you don't already have equipment picked that needs it (most popular is 30 and 50) change it out to a 30.

 

[alfredeneuman]

There's no such thing as a 40 amp outlet.
A 40 amp circuit uses a 50 amp outlet (receptacle)

You'd have to change both the receptacle and the breaker

 

[Stevematt21]

Attached below is the manual for the saw.. It has the ability to convert over from 110 to a 240

 

[Stevematt21]

Here is the pic

 

[Stevematt21]

What do I need to change the breaker to?

 

[sberry]

Is there a thermal reset button on the motor?
I would be tempted to leave it 120 if I had a good circuit. have one with a hp motor, left it 120 and have never tripped a breaker.

 

[Stevematt21]

I believe there is a thermal reset

 

[DekeT]

and breaker, dont leave your 15 amp table saw on the 40 amp breaker.

Why not?

 

[lucky1]

As another person commented, you are allowed to put a 50amp receptacle on a 40 amp circuit. It's what I just did. I believe you have to label it as such..for example "Welder Only". A lot of the Harbor Freight Welders have a 6-50p plugs in their 240v welders. The one I'm getting only draws 26 amps max but has 50 amp plug. I see no reason why you can't wire a 6-50p on your table saw. The saw motor will only draw the required amps and has built in overload protection.

 

[lucky1]

Here is the pic

If that's from the manual of the Rigid saw sold at HD, it's the exact same one I plan on buying. I've read and saw YouTube videos that say the saw runs noticeably better and cooler on 240v vs. 120. I'm curious about that myself.

 

[IlliniJeeper]

Why not?

There's no reason to worry about that. You leave 0.2A cell phone chargers plugged into your 15A or 20A circuits all the time without issue, there's nothing wrong with having a machine with a lower amperage draw than you circuit. That breaker is to prevent damage in the walls from overheating the wires. From the receptacle to the machine, it's the job of the machine to control that current draw.

 

[dw1]

Why not?

If there is not any overload protection on the motor itself and the 15 amp motor is fused at 40 amps, you could risk burning up the motor before the breaker would trip.

 

[thewatusi]

The breakers are to protect the wiring, not what is plugged in.

 

[Bondo]

The breakers are to protect the wiring, not what is plugged in.

Ayuh,.... Ditto that,.... No reason what so ever to change the breaker,...

 

[alfredeneuman]

There may be a place in the Manual where it states the electrical requirements.

If you installed a 15 amp receptacle on the 40 amp circuit it would be a violation.
If you you cut the plug off the saw and replaced, it would void the warranty.

Better idea to replace both the receptacle and breaker.

 

[dw1]

I would apply 430-52 and the inverse time CB he got from HD or Lowes-FLA @ 250%
I wouldnt care as much about my $3.00 cell phone charger to my $300 table saw motor over a $10.00 CB.
Or possibly 430-32 A 1
Does the motor have a thermo overload switch built in?

 

[Jeff Ivers]

Why not create a short pigtail with a 40 amp plug on one end to plug into your outlet and a 15 amp receptacle end on the other end to plug the saw into? In other words a very short extension cord with the appropriate plug and socket.

 

[Stevematt21]

I would apply 430-52 and the inverse time CB he got from HD or Lowes-FLA @ 250%
I wouldnt care as much about my $3.00 cell phone charger to my $300 table saw motor over a $10.00 CB.
Or possibly 430-32 A 1
Does the motor have a thermo overload switch built in?

What does all this mean?


I think it does but not known for sure.. It is a rigid r4512 table saw.. Have not purchased it yet ..


What circuit breaker would I need to put in ?

 

[pattenp]

The proper plug and receptacle is a 6-15P and 6-15R. Using a 15A DP breaker. Don't use any rigged up adapters, do it right.

 

[Aceman]

The proper plug and receptacle is a 6-15P and 6-15R. Using a 15A DP breaker. Don't use any rigged up adapters, do it right.

This is the right way. The manufacturers literature states to use all 15 amp devices and a 15 amp breaker.

So, you need to replace the breaker and pigtail #14 off the existing #8 wire to the receptacle. Done.

 

[alfredeneuman]

(2)

What both of these posters say

 

[Mustang51js]

The point of changing the breaker is so you don't burn your house down, a 14 wire would melt if it's overloaded before the 40 amp breaker would trip

 

[dw1]

What does all this mean?


I think it does but not known for sure.. It is a rigid r4512 table saw.. Have not purchased it yet ..


What circuit breaker would I need to put in ?

Sorry, had to go rescue my daughter!!

Anyway, in my opinion!! I would change the breaker, your wire is more than big enough, and as stated in a few other post's, you can change the recept and cord cap. What is the amperage of the motor @ 240 volts?

 

[alfredeneuman]

The plug already on the saw plugs right into a 20 Amp receptacle in addition to the 15 Amp receptacle

and use a 20 amp breaker instead of the 15.

 

[Lassen Forge]

As long as someone didn't underwire your house/shop circuits, you'll be fine - change to the correct plug and go.

Where you have problems is when, say, a circuit is wired (in the wall) for 20 amps, someone keeps popping 20 amp breakers (BTW - if it's wired for 20, the breaker should be one step BELOW that, or 15) so they put a 30 amp breaker in its place. Your wall wires heat up, the insulation starts smoldering (as does your wall framing), and then you wish you'd brought marshmallows to what used to be your shop.

If you want greater protection for your saw, either (a) install a breaker or overload on the saw (not a tough job, BTW) or put a smaller breaker between the wall plug and your saw. I run my little old craftsman 110 tablesaw through a 15 amp protected plug strip that is bailing wired to the leg. If the blade jams and pops the 15a plug strip - no big deal, de-energize and reset it, and carry on. If for some reason the power strip doesn't cut off, the wall breaker (which pops at 20a) will cut loose.

Being 220, you won't have the powerstrip option, but you can wire a 15A breaker between your motor and the plug (for gods sake, put it in the right enclosure!!) and attach it to the leg of your saw for the same effect.

 

[DekeT]

If there is not any overload protection on the motor itself and the 15 amp motor is fused at 40 amps, you could risk burning up the motor before the breaker would trip.

EVERY electrical device in my home and shop draws considerably less amperage than the allowable circuit amperage it is on. A dozen or so of them cost considerably more than a table saw motor. I don't see your point at all about disconnecting these electrical devices.

 

[dw1]

EVERY electrical device in my home and shop draws considerably less amperage than the allowable circuit amperage it is on. A dozen or so of them cost considerably more than a table saw motor. I don't see your point at all about disconnecting these electrical devices.

I didn't say anything about disconnecting those devices, they are on a 120v general purpose lighting/receptacle and or appliance circuits. The poster was asking about hooking up a Table saw 240 volts on an exsisting 40 amp circuit. With the above articles I mentioned from the 2014 National Electrical Code, I was saying to change the CB for protection, if you take the 13 amp - 120 volt or 6.5 amps 240 volt load and use an inverse time CB @ 250% of FLA would be 16.25 amps, even in the owners manual of the saw, the manufacturer states to fuse 240 volt circuit at 15 amps. This is one circuit and one device.
If you Leave the 40 amp breaker in there, this would be fused at over 600%
at 240 volts.

 

[dw1]

Another for instance: The newer-higher efficient air condition condenser units, a lot of people are replacing their units with new - high efficient units, the old units had a 30 amp CB, the new units states from manufacturer to fuse at no more than 25 amps, well, guess what has popped into the supply houses now, 25 amp Circuit breakers and they are more expensive than a double pole 30,40 or 50. Go figure. Leave the 30 in there and they will fail the inspection.

 

[alfredeneuman]

From the instruction manual:

Plug your table saw into a 220-240 V, 15 amp., 3-prong receptacle. Make certain the receptacle is connected to a 240 V, AC power supply through a 240 V branch circuit
having at least a 15 amp capacity and protected by a 15 amp time-delay fuse or circuit breaker.

That pretty much eliminates any of the "alternative methods" mentioned here.

The receptacle is limited to a breaker size of 15 amps if a single receptacle is used, and 20 amps if multiple receptacles are installed.

 

[DekeT]

Another for instance: The newer-higher efficient air condition condenser units, a lot of people are replacing their units with new - high efficient units, the old units had a 30 amp CB, the new units states from manufacturer to fuse at no more than 25 amps, well, guess what has popped into the supply houses now, 25 amp Circuit breakers and they are more expensive than a double pole 30,40 or 50. Go figure. Leave the 30 in there and they will fail the inspection.

Well, the "code" as my electrician friends tell me is all about selling more product for the suppliers. And thanks for the explanation about the 240 circuit breakers.

 

[Rock knocker]

Another for instance: The newer-higher efficient air condition condenser units, a lot of people are replacing their units with new - high efficient units, the old units had a 30 amp CB, the new units states from manufacturer to fuse at no more than 25 amps, well, guess what has popped into the supply houses now, 25 amp Circuit breakers and they are more expensive than a double pole 30,40 or 50. Go figure. Leave the 30 in there and they will fail the inspection.

Who says they would fail inspection?

 

[The Cobbler]

Well, the "code" as my electrician friends tell me is all about selling more product for the suppliers. .....

and nothing to do with safety


does the OP have 240/120 or just 240 to the garage circuit?

 

[alfredeneuman]

Who says they would fail inspection?

"the new units states from manufacturer to fuse at no more than 25 amps", as dw1 said .... and it would fail if not installed according to the manufacturer's recommendations. The nameplate is right on the unit, and gives the Max fuse or breaker size.


DekeT:

"Well, the "code" as my electrician friends tell me is all about selling more product for the suppliers."

Your electrician friends are some real dummies, then.

 

[Stevematt21]

I have one dedicated 240 volt outlet with its own circuit.

Several other 120v outlets in the garage

 

[Alchymist]

As another person commented, you are allowed to put a 50amp receptacle on a 40 amp circuit. It's what I just did. I believe you have to label it as such..for example "Welder Only". A lot of the Harbor Freight Welders have a 6-50p plugs in their 240v welders. The one I'm getting only draws 26 amps max but has 50 amp plug. I see no reason why you can't wire a 6-50p on your table saw. The saw motor will only draw the required amps and has built in overload protection.

This label is only required where it is a dedicated circuit for a welder where the breaker is oversize for the wire size, for example #12 wire on a 30 amp breaker. It can only be used where the load is an intermittent duty cycle.

OP, Give some thought to replacing the outlet with a small sub panel, then adding whatever circuits from there. You can have several new circuits sized as needed.

 

[dw1]

Well, the "code" as my electrician friends tell me is all about selling more product for the suppliers. And thanks for the explanation about the 240 circuit breakers.

Deke, see if you can borrow copy of the 2014 NEC from one of your buddies. Look at the first paragraph in article 210. Then flip on back to article 430 (Motors) plenty of reading there.
We just want to be safe with the protection of people and property.

When I first ran across the Air Cond CB sizing issue, the inspector did give me time to run to the supply house and change it out (Lesson learned on my part) and now I look and dont take for granted (I'm lazy sometimes)
But the AHJ said he would fail it, if I left the 30 amp in and didnt change it to 25 amp, my reply was where in the world will I find a 25 amp CB, he then educated me.

Steve, the article numbers I mentioned above are 2014 National Electrical Code Articles. Sorry to make this more confusing than it needed to be, but you now have plenty of info to go on.

Now make all this snow go away, it is putting a damper on my pole barn build.
Sunny and 60* would be nice!

 

[DekeT]

Your electrician friends are some real dummies, then.

I did not want to personalize this and I don't think you should either.