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13 posts 1 2

15 amp vs 20 amp

#20167 by webzter » Sat Aug 02, 2008 3:26 pm

I hope this is the right forum to ask this question. I am planning to wire in a dedicated circuit for my Mark V 500 using a circuit breaker and am a little confused on the proper amperage to use. In the manual it states that a 15 amp circuit is required but if you can use "wire and receptacles rated to handle 20 or 25 amp will give you an even bigger safety margin" and then in the next paragraph it says not to use a circuit breaker over 15 amp. I have purchased the matarial to wire in a 20 amp breaker but I don't want to proceed any further until I get this clarified. Any help would sure be appreciated.

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#20168 by a1gutterman » Sat Aug 02, 2008 3:36 pm

webzter wrote:I hope this is the right forum to ask this question. I am planning to wire in a dedicated circuit for my Mark V 500 using a circuit breaker and am a little confused on the proper amperage to use. In the manual it states that a 15 amp circuit is required but if you can use "wire and receptacles rated to handle 20 or 25 amp will give you an even bigger safety margin" and then in the next paragraph it says not to use a circuit breaker over 15 amp. I have purchased the matarial to wire in a 20 amp breaker but I don't want to proceed any further until I get this clarified. Any help would sure be appreciated.
Hi webzter,
The manual is a bit confusing. If you use 14 guage wire in your wall, you must KNOT exceed a 15 amp breaker. If you use 12 guage wire in your wall, you may use either a 15 amp or a 20 amp breaker. If you use 10 guage wire in your wall, you may use a 15 amp, 20 amp, or 30 amp breaker. I believe that your desired protection is with 12 guage wire and a 20 amp circuit breaker. If you are concerned about what the manual says, use 12 guage wire with a 15 amp breaker and upgrade to a 20 amp breaker if you have trouble. :) There is more discussion on this subject elsewhere on this forum.

---

Tim

Buying US made products will help keep YOUR job or retirement funds safer.

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#20169 by a1gutterman » Sat Aug 02, 2008 3:47 pm

webzter, see post 5 of this thread to see what Nick has to say about ths subject: http://www.shopsmith.net/forums/showthread.htm?t=1126&highlight=amps

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Tim



Buying US made products will help keep YOUR job or retirement funds safer.

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#20170 by webzter » Sat Aug 02, 2008 3:53 pm

Thanks Tim. That clears up my concern. I will proceed with the 20 amp breakera and #12 wire.

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#20175 by dusty » Sat Aug 02, 2008 4:52 pm

What Tim has recommended will work for you just fine and it will not get you into a conflict with any building inspector.

Just don't put a 30amp breaker in anything less that a 10 gauge run and don't put a 20amp breaker on a 14 gauge run.

Not only are these probable code violations, they are also good was to create fires where fires are not wanted.

I ran, trouble free, for many years on a 14gauge run and 15amp breakers. The only time I had trouble was when someone else was in the shop with me and tried to use additinal equipment simultaneously.

Oh, I did have to pay attention to where I plugged in the dust collector. If the DC was turned on while the Shopsmith was running it would kick the breaker if both were on the same service run.

Both run harmoneously on the same circuit if wired as recommended by Tim (12gauge run and 20a amp breaker).

---

"Making Sawdust Safely"
Dusty
Sent from my Dell XPS using Firefox.

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#20185 by beeg » Sun Aug 03, 2008 3:28 pm

Webzter

[color="Blue"]Just make sure you get a slow blow breaker. It's made for circuits that have a motor on it and can handle the start up surge.[/color]

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SS 500(09/1980), DC3300, jointer, bandsaw, belt sander, Strip Sander, drum sanders,molder, dado, biscuit joiner, universal lathe tool rest, Oneway talon chuck, router bits & chucks and a De Walt 735 planer,a #5,#6, block planes. ALL in a 100 square foot shop.
.
.

Bob

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Receptacles are not all equal

#20205 by cowboyplus » Mon Aug 04, 2008 1:30 am

When sizing electrical delivery systems, one of the most overlooked specifications is the selection of the terminating receptacle.

Duplex receptacles tend to look alike, maybe just in different colors. Oh, not so. Receptacles have amperage ratings as well as the carriers and overload interruption devices.

A 20 amp circuit, especially in a dedicated equipment environment, needs to have a 20 amp terminal. Below is a photo of a 15 amp and a 20 amp receptacle. Notice the neutral slot in the 20 amp terminal is a “T” shape. The 20 amp receptacle has a more robust spring clamp for each plug spade making it capable of delivering a full 20 amps.

The appliance plug connector should be kept clean and lightly sanded, if tarnished, for efficient operation.

Image


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#20207 by a1gutterman » Mon Aug 04, 2008 1:53 am

Cowboy is correct, and the SS manual also states it, as webzter posted:
webzter wrote:I hope this is the right forum to ask this question. I am planning to wire in a dedicated circuit for my Mark V 500 using a circuit breaker and am a little confused on the proper amperage to use. In the manual it states that a 15 amp circuit is required but if you can use "wire and [color=red]receptacles rated to handle 20 or 25 amp will give you an even bigger safety margin"[/color] and then in the next paragraph it says not to use a circuit breaker over 15 amp. I have purchased the matarial to wire in a 20 amp breaker but I don't want to proceed any further until I get this clarified. Any help would sure be appreciated.
and if you install a wall switch in this circuit, it too needs to be a 20 amp rated switch.

---

Tim



Buying US made products will help keep YOUR job or retirement funds safer.

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#20214 by Ed in Tampa » Mon Aug 04, 2008 12:20 pm

webzter wrote:I hope this is the right forum to ask this question. I am planning to wire in a dedicated circuit for my Mark V 500 using a circuit breaker and am a little confused on the proper amperage to use. In the manual it states that a 15 amp circuit is required but if you can use "wire and receptacles rated to handle 20 or 25 amp will give you an even bigger safety margin" and then in the next paragraph it says not to use a circuit breaker over 15 amp. I have purchased the matarial to wire in a 20 amp breaker but I don't want to proceed any further until I get this clarified. Any help would sure be appreciated.



First let me clear up a serious misconception. Increasing the amperage of a circuit (done corrctly of course) does not mean the device plugged in will get more amperage. It simply means the circuit can handle more amperage.

A device (properly functioning) will only draw as much current as it needs and is designed for. Problems occur when the device can't get enough current and trips the breaker or if circuit is marginal and device experiences a lower voltage which will increase it's amperage demands.

Second the breaker in the circuit box is not there to protect the device plugged into the circuit but it there to protect the circuit. A 15 circuit breaker means it will only allow 15 amps to be drawn on that circuit. If you have a device that for some reason draws more the breaker will trip thus protecting the circuit not necessarily the device. It is possible that a malfunction in the device could cause an current draw that would destroy the device but never trip the breaker. Example you have a device that is built to draw 3 amps, for some reason a component fails and the draw jumps to 10 amps, everything in the device can be fried and it can in fact catch fire but would never trip the breaker. I believe more than one house has burnt down because a heating blanket malfunctioned shorted but not enough to exceed the breaker rating and caught fire.

Shopsmith says their machine operates on 115volt at 15 amps or less and this is verified by the UL approval. (UL will not approve any 115 volt device that draws more than 15 amps I believe). However what Shopsmith doesn't say is if the line voltage at the machine is too low it will draw more current and a breaker is liable to trip.

By upgrading your circuit to 20 amps circuit you will have to upgrade the wiring from a 14 gauge to 12 gauge that one factor has a positive effect. A 12 gauge wire will have less voltage drop than a 14 gauge wire for the same lenght run. That means the voltage the device sees will be closer to it's exact need and therefore it's amp draw will be lower. Also while the inside components of the SS are only rated at 15 amps the safety margin built into them will probably keep them from self destructing should a short occur (your wiring insulation wore through and your wire touched bare metal).

I have my SS on a total 20 amp circuit, 20 amp breaker, 12gauge wire, 20 amp connections. I even changed the line cord from the stock 14 gauge to a 12 gauge and I attribute that change for making a marked improvement in the realized power of my SS. I have no impericial data to support that claim but to me my SS seems to work better.
Ed

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#20246 by jg300da » Tue Aug 05, 2008 9:59 am

Ed in Tampa wrote:... I even changed the line cord from the stock 14 gauge to a 12 gauge and I attribute that change for making a marked improvement in the realized power of my SS.
Ed


Bingo. The circuit breaker is there to protect the WIRE. Nothing else. It doesn't care what type of load is connected, inductive (like the Shopsmith) or resistive (like incandescent shop lighting).
Upgrading the wire from the panel to the Shopsmith outlet means nothing unless you also upgrade the 14ga SJ cordset that came with your Shopsmith from the factory as Ed did. The circuit is only as strong as the weakest link.

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