110/220, why

[HR masters]

Please explain to this amperage illiterate WW why I can run 2 machines drawing 8 amps each on a 20 amp 110 circuit and can't run 2 machines at same time that draw 12 amps each on a 220 thirty amp circuit. I am about to take the 1-1/2hp motor from my fifty+ yr old Atlas 3110 and put it in my 40+ yr old Sprunger jointer, and put a 3hp in my TS. I want to run my DC at the same time as my TS. Is there away to run both without a dedicated 220 for both DC and the TS? thanks HR

[Howard Acheson]

Theorectically you can. You might run into problems with the high startup amps required to get your DC rotor going but once running, it will run fine. You will also have higher than rated "running amps" on startup of your saw but the amps will not be as high.

That said, the NEC codes requires separate circuits for peices of heavy equipment I believe.

[Steven Wilson]

That said, the NEC codes requires separate circuits for peices of heavy equipment I believe. Well not really. There is the section of the NEC that covers motor circuits and discusses having multiple motors on one circuit. That same part of the NEC also discusses having fairly large breakers on smaller cable inorder to handle startup current. Most of us though don't wire up motor circuits as described by the NEC, we use the more conservative Branch Circuits. Or as my Electical Inspector said, if you have a plug and cord on it, it's a branch circuit. Only go the motor circuit route if you really need to. So, in our shops we can generally wire up 220v branch circuits with multiple outlets. Of course our breaker will match up with the wire guage used and it's up to us to make sure that the total load is within that allowed by the breaker/wire combination. Of course, your local Electrical Inspector is the final authority for where you live; YMMV.

[Jeff Horton]

That said, the NEC codes requires separate circuits for peices of heavy equipment I believe.

Oh your going to chastised for thinking and not quoting chapter and verse of the code! Better put on your hard hat!! !:eek:

[Rob Russell]

Jeff,

A hard hat? Wouldn't it be more appropriate to put on insulated underwear!? You have gotten the point, though, that we should be sure about the code if we're going to reference it. :)

Steven has already posted the gist of my comments. FYI (Howard), the heaviest machine that any of us has isn't likely to be anywhere near what is considered to be a large machine. Once you hit 50 HP, you're starting to get into decent sized machines. When you're talking about big, the HP ratings are in the thousands.

HR,

The biggest rule you'd want to be concerned about is that your conductors match the breaker size, so that means #10. 30 amp circuits can't have the normal receptacles either - you need to use receptacles that are rated for 30 amps.

Once you update the motor on your table saw, you may have problems trying to run both that and a DC at the same time. It'll mostly depend on the startup draw of the machines.

FYI, we use real names on SMC - not madeup monikers. Send a message to the admins (click on the "Contact Us" link at the bottom of the page) with your real name and they will update your profile.

Rob
Addy protocol: unlicensed, experienced homeowner electrician

[Jeff Horton]

Jeff,

....You have gotten the point,....


Don't flatter yourself. I got a point, just not the one you think.

[Rick Christopherson]

As has been already said, you won't have any problems with putting both tools on the same circuit. I do have to disagree with the concensus that you will have a problem during startup. If I understood your message correctly, wasn't one of the motors 1-1/2 hp? If so, then you could start the motors simultaneously without having a problem, let alone having a staggered start.

Even if both motors are 3 hp, they will still operate and start just fine, but you wouldn't want to start them simultaneously.

[Rob Russell]

We don't know what HP the DC is - just the table saw and jointer.

[HR masters]

I appreciate you sharing your electrical knowledge but if you want to berate me for something you nothing about, you are walking on the wrong side of me. You are free to go on my website my name and picture are prominately displayed. Is it Rob, robert or bsomething else? HR

[Charlie Velasquez]

Oh your going to chastised for thinking and not quoting chapter and verse of the code! Better put on your hard hat!! !:eek:
These types of questions come up often, and sooner or later some one mentions "the code says..."

Is there someplace online that a person can access the code.
As the "code" is integral to safe installation, you think it would be in the best interest of towns, municipalities and other organizations to have a copy on-line that is free and easily accessible to all.

So, is there such a web site?

[Peter Mc Mahon]

Rob Russell, Howard said "I believe", therefore stating that he does not know for a fact. I am guessing that he is merely trying to help someone and makes mention of saying that with the disclaimer "I believe". Peter.

[Tom Jones III]

Is there someplace online that a person can access the code.As the "code" is integral to safe installation, you think it would be in the best interest of towns, municipalities and other organizations to have a copy on-line that is free and easily accessible to all.
So, is there such a web site?

I have not been able to find such a web site. You can go to the nec site, but to get anything you have to pay big. Even if you paid the ridiculous amounts, I'm not sure most of us would get anything out of it. I don't believe that is was written for consumers. You can find forums similar to this one that are for electricians. There are also various handbooks that you can get at the borg and electrical supply places written for consumers through reminders for professionals. Be careful that you are not making yourself more dangerous through a little knowledge.

It seems people just are not going to refer to chapter and verse of code and will always just state their opinion. When they give their opinion hopefully the people who are reading it will realize the value of such an opinion and not waste too much time or money or create too dangerous a situation.

[Don Baer]

To anwer your original question you can. I built industrial motor control panels for a number of years. When we would size conductors, beakers etc. the NEC clearly states that you should size the service for "100% of all of the motors connected to the circuit and 150% of the largest load". If one were use this analagy in your case you would take the FL apms of 8 amps x2 plus 4 additional amps that would mean 8 amps+12 amps(8x150%)=20 amps.

I can't site part of the code where this answer lies but I did stay at a Holiday Inn express last night.

[Ken Salisbury]

In order to be a bona fide member of Sawmill Creek you must use a real first and last name. Please PM Jackie Outten with that information and she will update your registration accordingly.


http://oldrebelworkshop.com/misc/moderator.gif

[Rob Russell]

Ken,

HR Masters is his real name, at least it's how he is known professionally. You can see that by looking at his website. While a bit confusing to some, there are people who don't use their first name - ever.

HR - please accept my apologies. The assumption that I made was that your use of initials and masters was referring to some sort of Human Resources company name. I intended no offense.

Rob

[Allen Bookout]

there are people who don't use their first name - ever.

That is a truism. Just spend a little time in West Texas.

[Andy Haney]

that was posed by Charlie V. I checked with our City Inspector today, and he said those who publish the Codes have copies for sale, and there are copyright laws (or such) relative to posting those on-line. I know nothing of the details, but our Inspector referred me to this website as a possible resource for you folks who may be interested.

http://www.mikeholt.com/index.php?id=homegeneral

Hope this is helpful to someone.

Andy Haney

[Kent Fitzgerald]

Is there someplace online that a person can access the code.


If you mean the National Electric Code, no. The NEC is published and copyrighted by the National Fire Protection Association, a private organization, and they're not in the business of making it available for free.

[Steven Wilson]

You can access the NEC Code at your public library or buy a copy of it most anywhere. It's not that expensive. Sooner or later every good bookshelf should have a copy.