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240VAC Outlet wiring suggestions

daen's picture

240VAC Outlet wiring suggestions (post #194786)

I am building my own workshop and I am currently installing the electrical. I am interested in suggestions on how to wire in a 240 Volt circuit.

My shop has several 120V 20A general purpose circuits. I am adding a couple of 240V 30A circuits for some heavier equipment like tablesaw, jointer, planer, etc. The 240V circuits will feed two or three receptacles each. My choice of 30A for the circuits is more "just because" instead of from load calculations. I have plenty of panel capacity (200A) and I could conceivably have two machines running at the same time (two people working together, not me with four arms). Also, most of the equipment I intend to run off these circuits is still on the "wish list" so I don't have any nameplate specs.

I do have the jointer though. It has a 250V 15A NEMA 6-15 type plug.

Now to my questions. Which receptacle style would you choose? I can nearly guarantee that no two pieces of equipment I purchase will have the same type plug. NEMA 6L-30 provides the amperage and twist lock. What is most common?

Next, I have pulled #10 for these circuits in EMT. I have pulled four conductors (Blk, Red, Wht, Grn). I know the neutral is probably overkill. But is this good future-proofing? And what would you do with the neutral if the receptacle choice has no place for it? Cap it in the box? Connect it to the neutral bus in the panel or cap it there too?

Finally, as I mentioned above, my jointer is equipped with the 15A plug. The nameplate rating on the machine is for 8.5A. I certainly don't want to put a matching 15A receptacle on the 30A circuit. Should I just change the plug on the jointer cord to a 30A version? Or do I need to derate my circuit to 20A. A jointer, dust collector, and something else at 8A each trips the 20A circuit...

Thanks in advance for your suggestions.

Daen

Ya may not want to use my (post #194786, reply #1 of 20)

Ya may not want to use my approach as you need to be a scrounger.

And not be needin' any permits.

Ah have about 30 either 50A or 30A 3 prong stove/dryer outlets around the place in various buildings. Usually have picked up the outlets and plugs/pigtails for 50 cents each here and there.

I always cut 1/2 of the ground prong off lengthwise so all plugs fit into either the 30A or 50A outlets. Some are fed by 50A circuits, some only by 12 AWG.

System has worked well for me for 40 years or more.

Welders, compressors, pressure washer, and pumps are the main type items with the 3 prong plugs.

I do have 3 specific stationary tools with dedicated plug/outlet pairs that are for safety (e.g. the cord goes up to the ceiling to plug in, that way the GKs cant plug in the RAS, 15" planer or 6" planer of table saw)

 

edit: separated paragraphs, noted that when it posted it was all run together.

The amperage issue is a tough (post #194786, reply #2 of 20)

The amperage issue is a tough call. In my case I've standardized on 4-prong 30A NEMA twist locks, protected with 30A breakers.

 

Yes, I plug the occaisional 20A device in, which is technically a code violation.

I'd probably use a big (post #194786, reply #3 of 20)

I'd probably use a big honkin' 4-prong twist-lock and then make up short pigtails as needed to mate to other plugs.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Nice to see someone else (post #194786, reply #4 of 20)

>>>I'd probably use a big honkin' 4-prong twist-lock

Nice to see someone else think the same way that I do.

I like the 4 pin solution because you've always got 120V and 240V available when needed. There were times when I went with 3 pin receps/plugs and got caught wishing I had 120V available.


Now the current issue....protecting a 15A appliance with a 30A breaker always used to scare me. Then an inspector once told me that a catastrophic fault current, like a direct short to ground, produces a transient that will trip a breaker, even if that breaker is rated at a higher amperage than the appliance. While this is some comfort, it doesn't address the problem of a less-than-catastrophic fault of say, 20A on a 30A circuit.

Thoughts?

For the lighter uses, make up (post #194786, reply #6 of 20)

For the lighter uses, make up a pigtail with a small breaker panel on the end of it.  I've seen jobsite units that incorporate like a 4-breaker panel and several outlets in one box.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(And, of course, you should (post #194786, reply #7 of 20)

(And, of course, you should run some  regular 120V circuits anyway.)


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

 ...protecting a 15A (post #194786, reply #15 of 20)

 ...protecting a 15A appliance with a 30A breaker always used to scare me.

Look at your kitchen wall.  It probably has a wall wart for your cell phone, cordless phone, pencil sharpener, PDA charger, etc.  Each of those might be capable of handling 1Amp of power on a good day if things went kerfluey inside the plastic shell.

That is no different from the 15 amp device on a 50 amp breaker.

YAY!  I love WYSISYG editing!  And Spellcheck!

____________________________________________________

Those wall warts all carry UL (post #194786, reply #18 of 20)

Those wall warts all carry UL ratings, which says they were tested by creating a dead short internally and making sure that no fire or other life/property-threatening event occurred as the wall wart destroyed itself.

Much different from installing a 15 amp device (with #18 line cord) on a 30 amp circuit.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

No Deal. "I don't  want" is (post #194786, reply #5 of 20)

No Deal.

"I don't  want" is usually followed by "no inspections." Do you want to do it right, or forever make excuses for doing it wrong?

Let's back up, and look at what all those pesky electrical rules are trying to accomplish. Believe it or not, but those pesky rules are not the result of ignorant schemers, conspiring just to make life hard.

The whole point of circuit design is to protect the wiring, the appliance, and maybe even you. I know, this is hard to understand, since the ordinary 'convenience' circuit -the one you're most familiar with- is the one exception to the rule. The plug on your jointer is a subtle hint as to what the jointer requires.

If you put your 15 amp jointer on a 30 amp circuit, you take away any chance that the breaker will trip should something go wrong with the jointer,

If you want your circuit to supply many tools, that circuit is no longer a 'branch circuit.' It is now a 'feeder.' This means you need to have correctly sized fuses or breakers at each tool. This detail might actually open up an entire set of advantages for your shop.

The easiest way of providing this protection is by using a 'combination' motor starter. That is, a box that has fuses, a contactator, a disconnect, and overloads ("heaters") all together. Use the starter to power a receptacle of the correct pattern.

The starter introduces a few other possibilities. First of all, it makes sure that the power tool will never automatically re-start after a power outage. Next, it makes it easy to tie your dust collector into the system, so it starts automatically when you start the jointer. You can easily tie in other things - task lights, additional 'stop' buttons, etc.

Expense? It amazes me that folks will go out of their way to buy the 'best' tools, the most premium materials .... then skimp on safety and proper design.

>>>The easiest way of (post #194786, reply #8 of 20)

>>>The easiest way of providing this protection is by using a 'combination' motor starter. That is, a box that has fuses, a contactator, a disconnect, and overloads ("heaters") all together. Use the starter to power a receptacle of the correct pattern.

 

Most awesome!! I've always wondered what a "starter" was. It always seemed like nothing but a switch to me, and now that I think about it the ones I've bought were nothing but a magnetic contactor (no fuses). I'll have to look for ones with fuses.

Thanks...good advice.

 

Scott.

More About (post #194786, reply #9 of 20)

More About Starters:

Strictly speaking, a 'starter' is defined as a contactor with overload protection. A contactor is a big relay.

What this means is that the power to your machine goes through some beefy contacts, then through 'heaters' that will open if too much current flows through them for too long a time. "Heaters" do NOT offer protection against short-circuits, so are no substitute for fuses or circuit breakers.

The contactator has a coil, that is often powered by the same source that powers the machine. That is, some of the power is diverted to power the coil. Since the coil requires only a very small amount of power, this part can use small wire and light-duty switches.

In addition to the 'power contacts,' a starter also has a much smaller 'auxillary contact.' This contact lets you use 'momentary' con tact push-buttons to start the machine. In the event of a power failure, this contact will open, keeping the machine from starting until the button is pushed again. A second 'auxillary' contact can be added, and used to operate the dust collector.

Now that you've described it, (post #194786, reply #11 of 20)

Now that you've described it, I see that I've used contactors before. I just didn't know that it was a relay that used line voltage for the coil and switched circuit.

As for starters, the one for my tablesaw has the magnetic feature which stops it from restarting after a power failure, but to my knowlege there is no overcurrent protection. I'll look for this with the next one I buy.

Thanks a mil.

More About (post #194786, reply #10 of 20)

More About Starters:

Strictly speaking, a 'starter' is defined as a contactor with overload protection. A contactor is a big relay.

What this means is that the power to your machine goes through some beefy contacts, then through 'heaters' that will open if too much current flows through them for too long a time. "Heaters" do NOT offer protection against short-circuits, so are no substitute for fuses or circuit breakers.

The contactator has a coil, that is often powered by the same source that powers the machine. That is, some of the power is diverted to power the coil. Since the coil requires only a very small amount of power, this part can use small wire and light-duty switches.

In addition to the 'power contacts,' a starter also has a much smaller 'auxillary contact.' This contact lets you use 'momentary' con tact push-buttons to start the machine. In the event of a power failure, this contact will open, keeping the machine from starting until the button is pushed again. A second 'auxillary' contact can be added, and used to operate the dust collector.

contrary (post #194786, reply #12 of 20)

contrary opinion....

starters fine if you paranoid - or have a big commercial shop with osha inspections.

most home or small pro shop 120/208/240 motors already have internal thermal protection.

i prolly got around 50 stationary power tools, not a starter on a single one of them except the biggest metal lathe (which came with a mag starter)

no starter even on my $30,000 CNC tree knee mill, just a 25A 3 phase breaker for a disconnect and internal wire protection. 

yur panel cbs are only for wire overheating protection (or gfi or arc fault), none are intended for load protection. 

By the time you buy all those (post #194786, reply #13 of 20)

By the time you buy all those 6L-30s you could have run a 30a circuit and a couple 20s with the appropriate receptacles.

Personally I have decided on a regular 3 prong dryer plug for my 230v 30a tools. It makes it handy if I have to go to someone elses house to work

Greg

Junkhound, I was describing (post #194786, reply #14 of 20)

Junkhound, I was describing starters in general. In this instance - notice I said COMBINATION starters - the fuses in the starter allow you to safely feed a 15 amp jointer from a 30 amp circuit.  To do as some suggest - simply change the plug and use the big circuit- goes against everything we know about electrical safety and is a code violation.

The other advantage to a starter is that it allows you to add controls and tie in other things, like the dust collector, to the operation of the tool.

Gfretwell ... of course a separate, proper circuit is cheaper. For some reason the OP doesn't want to do that. So, naturally, everyone and their brother came up with all manner of 'cheap' -and dangerous- fixes.

I suppose -to steal a line I saw somewhere- "Code minimum" is not an option here." Maybe if these folks know the possibilities, they'll talk themselves into doing it right.

"Fine" homebuilding is all about doing things 'right.' Guys here routinely argue passionately about who makes the "best" tool, and the magazine won't even consider reviewing cheap Chinese imports. I often wonder about the mindset that lets someone worry about using the 'best' tools to do the 'cheapest' work- but that's another thread.

3 phase connection (post #194786, reply #16 of 20)

Connecting  so many equipment simultaneously may overload one-phase circuit.

May be it is possible to use all three phases. 

 http://www.house-building-in-russia.com

I doubt that he has 3-phase (post #194786, reply #19 of 20)

I doubt that he has 3-phase power within a quarter mile, plus dealing with 3-phase power in this situation would be at least twice as expensive.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

No diffefrent? Well, that's (post #194786, reply #17 of 20)

No diffefrent? Well, that's where you're wrong. I'll try to explain why.

In electric work, we size our circuits to the loads. We want the fuse or circuit breaker to be no larger than it has to be, so that it may trip as soon as possible should there be a problem. This practice is a hard-and-fast rule, a basic principle, of the electric code.

Your household 'convenience' and lighting circuits are the only exceptions to this rule. To infer that you may now disregard the rest of the code, and reject its' basic reasoning, because of the exception is bad logic.

There's  no getting around the little detail that a 15-A, 240-v stationary power tool needs to have its' own overcurrent protection. Now, this can be done either at the panel (by running a new circuit) or by providing it where you draw from the larger circuit by adding it there (as part of the combination starter).

Your error is often found in non=permitted DIY remodels, where someone powers the stove, water heatrer, and dryer from the same 50-a circuit. Two words apply: illegal and dangerous.

Oddly enough, there has recently appeared a 'new technology' that would incorporate overcurrent protection into the plugs that come with appliances. Such has been done for decades in the UK, where the plug typically contains a fuse.

I don't know much from (post #194786, reply #20 of 20)

I don't know much from nothing about all the whys and wherefors involving circuits. What I do know is that emt and wire is relatively cheap. Especially when compared to the cost of building overall, the price of machines, and ones time. So pull dedicated circuits to each machine. You don't have to do it now... in fact, you can't since you don't have the machines. Simply surface mount emt later on when you acquire the new machines. Easy peasy, safe, to code, and fully adaptable.