Electrical help: 20 amp vs 30 amp

Page 3 of 4  
snipped-for-privacy@milmac.com (Doug Miller) wrote:

Which is why you're supposed to wrap some red tape around the white wire in the boxes at both ends, to indicate that it's a hot conductor.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If you have ground/neutral/hot, it's 110, not 220. If you're trying to run a motor designed for 220, you need to have two hots (one from column A and one from column B). Typically you would do this by putting on a different receptacle and moving rewiring the panel side of the circuit to go to a double-pole breaker. Standard practice is to wrap red tape around the white wire at both ends to indicate that it's now a hot conductor.
Be that as it may, amperage requirements are *minimum* requirements. If the machine needs 20 amps, it's perfectly fine to plug it into a 30 amp circuit. It won't hurt the circuit and it won't hurt the machine.
You do need to make sure you've got the voltage right. Many motors can be configured to run on either 110 or 220 by moving a jumper or connecting to different terminals, but make sure you got it right. A mixup in either direction won't be good.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If it can be configured to run on either, run it on the 220.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Do yourself a favor. Ask a qualified electrician. The advice you get here will be good/bad/bullshit. Do you know how to tell which one is which? If you did, you wouldn't have to ask. Ask the professional, it's worth it.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for the help everyone.
Since I already have the double 30 amp breaker and the 10 g wire with hot,hot,ground, I am going to use it as soon as I get to the Borg to get the proper outlet and plug.
Nothing like an electrical question to stimulate discussion - especially in a woodworking group!
Lou

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
A 20 amp two pole breaker is worth about 15 bucks. Although I agree in principle that the system should run fine on the 30 amp circuit, I wonder whether your warranty would still hold if something happened. The internal wiring on their machine will not be of adequate gauge for 30 amps of current. In the owner's manual they will say that they want a 20 amp circuit, not a 30 amp circuit. Sure, Grizz should have designed the system to internally trip with excess current. But if you blow the motor and Grizz find out that 30 amps were running through the wires, they might find cause to blame you for some of that problem. Changing the breaker is a one-minute job. Cheap insurance.
Dave
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you blow the motor and there was 30 amps running through the wires, it would indicate a defective motor.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Jan 2005 16:26:50 GMT, "Dave"

Please. You should refrain from offering electrical advice. I'm sorry if that hurts your feelings, but your reply does not reflect the slightest bit of reality with regard to electrical theory, engineering, or legal requirements.
- - LRod
Master Woodbutcher and seasoned termite
Shamelessly whoring my website since 1999
http://www.woodbutcher.net
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I think you are thinking that the circuit breaker protects the item powered by the circuit. This is not the case. The breaker or fuse protects the wire from being overloaded, not the device. Quite common to plug a 60 watt lamp into a 20 amp circuit. If the lamp developed a short to ground it would hit 20 amps in a big hurry.
On a saw, if you were trying to cut through some nasty gnarly sappy wood with a dull blade mounted backwards the thermal cutout would pop to protect the windings on the motor long before it would pop the breaker.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No. No.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'd just like to thank everyone again. The saw now has power.
I left the 30 amp breaker. Bought a single outlet rated 20 amps/240 v and a matching plug. It is dedicated to the saw (nothing else can/will be plugged into it).
It's a bitch working with that 10 g wire though.
The 1023 SL is just humming right along! I haven't put a blade in it yet - still fiddling with the wings & fence. I want to try to get everything as perfect as I can from the get-go.
Lou
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
A 20 amp two pole breaker is worth about 15 bucks. Although I agree in principle that the system will run fine on the 30 amp circuit, I wonder whether your warranty would still hold if something happened. The internal wiring and switches on their machine will not be of adequate gauge for 30 amps of current, so if a wiring fault occurs in the saw, the risks may be higher. Sure, Grizz should have designed the system to internally trip with excess current. Also, the resistance and design of the motor should automatically limit the amperage of the circuit. However, suppose that you started a fire caused by excessive current, and your house burned down. Would Grizz be expected to pay? In the owner's manual they say that they want a 20 amp circuit, period. I suspect they don't say 'minimum 20 amp circuit'. So their lawyers could argue that you made a mistake. If you blow the motor and Grizz find out that 30 amps were running through the wires, they might find cause to contest your claim. Changing the breaker is a one-minute job, and you can then say that you followed the owner's manual to the letter. You can always change the breaker back to 30 amp later, if you wired it as a 30 amp circuit. Cheap insurance.
Dave

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 14 Jan 2005 02:37:10 +0000, Dave wrote:

Oh, Dave - A BIG Thank You!
After reading your post and realizing the risks I've been taking with all those 60 watt lamps and 1/10th watt alarm clocks plugged into those humongous 15 and 20 amp circuits, I've rushed breathessly around the house and unplugged them all! Gawd only knows the risks we all take on a regular basis by plugging under-utilizing dangerous equipment into over rated outlets!!!
Thanks again for saving me from disaster with my insurance company!
In eternal debt to you,
- Doug
--

To escape criticism--do nothing, say nothing, be nothing." (Elbert Hubbard)


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Dear Doug,
Thankyou for your facetious comment, which I anticipated from someone. Those appliances are all rated to be plugged into 15/20 amp 110v AC outlets. So of course the manufacturers design those appliances with that point in mind, and with appropriate safeguards to protect consumers based on that maximum amperage the appliance could be subject to. However this table saw is designed to be plugged into a 20 amp circuit. Sure, I think it will work fine on a 30 amp circuit, provided there is no short circuit or higher than anticipated draw. I do wonder why Grizz didn't just say that it will work fine with 30 or even 50 amp breakers. But it didn't, maybe for reasons of liability.... Therefore this analogy that you are making is not an accurate comparison.
Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 14 Jan 2005 04:42:58 +0000, Dave wrote:

Dear Dave,
Breakers are designed to protect the wiring to the load, not the load. All modern motors (load) have thermal breakers integrated to protect the motor.
Your friend,
- Doug
--

To escape criticism--do nothing, say nothing, be nothing." (Elbert Hubbard)


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dave wrote:

Dave, you're way off here. Breakers are sized for the ampacity of the circuit wiring. As long as the <total> load on the circuit is within the rating, it's just fine and will do it's job as designed. There's no protection for the device itself (in this case the saw) implied by the breaker, simply the protection from overcurrent so that the household wiring does not overheat.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Doesn't every electrical question here on the wReck have pretty much the same effect as a troll? ;-)
Patriarch
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 14 Jan 2005 02:37:10 GMT, "Dave"

As I said before:
Please. You should refrain from offering electrical advice. I'm sorry if that hurts your feelings, but your reply does not reflect the slightest bit of reality with regard to electrical theory, engineering, or legal requirements.
- - LRod
Master Woodbutcher and seasoned termite
Shamelessly whoring my website since 1999
http://www.woodbutcher.net
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The Grizzly saw hookup originally asked about is a 3 wire hookup to the electrical switch. Hot-Hot-Neutral. If the wire has a white jacket on it, it is a neutral. Ground wires are bare.
Beyond that, if you open up your main service panel to your house, there SHOULD be a little green screw run through one edge of the NEUTRAL bar that connects to the back of the service panel, which in turn is connected to the GROUND bar in the service panel. That said in the main service panel there is a completed circuit between neutral and ground in a 4 wire hookup. In sub-panels, the "green screw" is removed and the 4 wires (hot-hot-neutral-ground) are run separately to the main service panel. It's just a formality done so that an electrician can tell it is a sub panel, since back at the main panel the ground and neutral are combined...see above. This is according to current NEC code.
So, the whole neutral or ground argument is mute...they connect together back at the panel. Therefore, if it's got a white jacket, call it neutral, if it's bare, call it a ground.
Kevin
On Fri, 14 Jan 2005 13:36:39 +0000, LRod

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Just a formality? Like Dave, above, you should not be giving electrical advice.

While you may have actually looked at the code, you _clearly_ didn't understand it.

You couldn't be more wrong.
scott
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.