Seeking advice: size of circuits to add?


sjk

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I'm going to add some wiring to my garage shop before I finish insulating and drywalling it.  I've read through a pile of threads here and elsewhere and am confused.

To make sure I have headroom, I looked at the manuals of several big 5hp machines at Powermatic, Oneida, ClearVue, and Sawstop.  I found listed amperages of 28A (like on the PM 209 planer), 19.5A (Oneida Super Dust Gorilla), 21A (PM2000 table saw), 30A (ClearVue), 20.5A (Sawstop).  I don't see myself buying 5HP machines, so I'm thinking those would be upper bound.

In forums, including here, I see conflicting things like "I need 40A" and "I run my whole shop on a 50A subpanel".

 

I'm planning on adding 3 220v outlets (I have none, and no current tools that are 220).  From the machine manuals it looks like 30A outlets would leave room to spare.  What amperage would you recommend?

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I'm also in shop planning mode, so going through some of the same thoughts.  Have a few big 220 tools and have my eye on a few upgrades at some point in the future.

My thinking was to run wire capable of running a 30 or 40 amp tools (10 or 8 gauge I believe) to all the likely spots (and 1-2 "maybe" spots).  I assume I can then put in the right size breaker for the given tool.  My desire is to have the wiring run just in case because I don't want to open the walls up again later, if at all possible.

I could easily be wrong here - it's on my list of things to discuss with the electrician... so 10% sharing my thoughts and 90% tagging along for the ride for the answers you get.

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First, I'm not an electrician by trade, but am wiring my own shop and have a cursory understanding of simple circuits, said another way, I'm not an expert ha. 

That said, the real determinate is the wire guage, you can't use thinner wire on larger breakers so if you get your wire size right, the breaker will follow.

Second, are you really going from no 220 tools to several that require 30 amps?  That seems like a very large jump for someone IMHO, as my 2hp jet dust collector only requires 20 amp and my 8 inch jointer is 15. 

I would suggest running a more moderate 12 guage 220 that would support 20 amps and if you ever need more, run conduit - I think 10 guage is pretty nasty to work with and you'd have a better sense of your shop layout so you may only need one receptacle. 

Matt, sounds like you're figured out so would be interested in what the electrician tells you  

I consider myself pretty handy but draw the line at adding a 20 amp 220 circuit to my box...any bigger than that and you might want to consider a professional since I think it gets more complicated  

 

 

Edited by tedfmcm
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I just went through the same thing. I can tell you what I did, then someone who knows what they are doing can actually provide help.

I ran 60A out to the garage to it's own panel. Currently there are 3 20A, a 30A 220 and a 20A 220. 

It's real hard to know what I need but at least this way I can configure as needed. There are very few situations where I would need more than 60A total. And those are going to be ones that involve heat or a/c in addition to dust collection and a tool. 

At least for my level of desired woodworking.

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Most 220V machines including DC are going to be satisfied on 20amp circuits. And ironically, most 110V tools are going to be satisfied with a 20A circuit. Unless you know for certain you are buying something that will draw more amps, you're fairly safe wiring your shop with that in mind. 

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Obviously, shop electric is a wide-open field. A forum thread can’t tell you all you need to know. Your best bet is to hire a licensed electrician...

 

I’ll try to clarify a few points... I’m not an electrician, nor do I play one on TV, so YMMV.

 

==>I see conflicting things like "I need 40A"

Let’s take the 5HP. Why the different amps? There’s the no-load draw, load draw, max-load and inrush... Typical 5HP would be: 21a no-load, 27a load and around 32a max (depending on SF). The inrush would be closer to 75a... Typical breaker would be 30a-40a depending on the type of load – for example, a 5HP DC may be on 30a (constant nominal load) while a 5HP planer might be on a 40a (varying load). Most manuals would recommend 40a (remember 32a max draw) and some 50a (to account for inrush). There are other factors like efficiency, but we'll just ignore that. The requirement is on the motor plate, not the manual.

Per code, devices (outlets) must match breakers... Most of my branches are 30a. However, most of my 30a are end-runs (one tool per branch). The DC is also end-run. My branches are all up-gauged. All this uses up breaker positions quickly. All the 5HP tools and up are end-run to the panel -- again, per code. You tend to use-up breaker positions pretty quickly in a woodshop, if you follow code... You use-up breakers very quickly once you hit 40a branches...

Never assume you’ll only use one tool at a time. The DC is always on, the lights, heater, etc. These all use power. You can suck 30a-40a right off the top before using a single tool. I sometimes run two tools at once: jointer + TS;  jointer + BS; jointer + planer; and planer + sander. I’m sure there are other combos, but not as frequent. So you may have lights + heater + TS + jointer + DC + tunes + TV + beer cooler + ??. That could be 40a-50a right there...

If possible, run a sub for the shop. It gives you flexibility. Shops are rarely static environments. Run a 125a sub (it's maybe $25 more than a 60a sub), you’ll never need the power, but you’ll want the available breaker lugs. Also, there's more 'room' to maneuver in a 125a sub.

 

==>I don't see myself buying 5HP machines

Never say never. You might see some nice 5HP tool needing a good home on Craigslist.

 

==>I assume I can then put in the right size breaker for the given tool. 

Don’t mix 20a and 30a branches. Run all 30a. Trust me, shops are never static environments. So all my 15a, 20a and 30a tools run on 30a outlets/branches/etc. If the tool has a plug, I replace it with a 30a. Why? Experience. I've learned that shops reorganize and after you run the branches, you don't want to do it again... So don't mix, just run 30a... So why not just run 40a or 50a? You can't, per code... Things change when you get to 40a. Again, hire an electrician for the big stuff...

 

==>I run my whole shop on a 50A subpanel

A given sized sub has max amps and max breakers. My shop draws around 57a, no-load... So a 60a sub would just cover it, but not under load. I have a 125a panel more for the available breakers than the required amps. Also, don't forget about the 120v circuits -- you'll need a few of those: ShopVac+Router+Chargers+??

Note: In my 125a sub, all breaker positions are now occupied. Because of that, I violate code by sharing a single branch with two separate 5HP tools that aren't run concurrently (but don't tell anyone that, it's a secret)...

 

Hope some of that helped.

Edited by hhh
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One more point to consider is duty cycle on the machines. As hhh mentioned, electric motors have an 'inrush', or startup current that can be as much as 10 times the nominal load current. Such machines, if fed from a breaker sized for the 'full load amp' rating of the motor, will start tripping the breaker if cycled on and off repeatedly, as is common for a tablesaw in a hobbyist's shop.

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apologies to @sjk, I'm not trying to hijack his thread, but just wanted to clarify a few of @hhh's comments above.

 

two quotes caught my eye:

  • "Per code, devices (outlets) must match breakers... Most of my branches are 30a. However, most of my 30a are end-runs (one tool per branch). The DC is also end-run. My branches are all up-gauged... "
  • "Don’t mix 20a and 30a branches. Run all 30a. Trust me, shops are never static environments."

"up-gauged" - meaning you're running thicker wire?  a 30 amp is 10 gauge wire, right?  You're running 8?

So even if something has specs that require a 20amp, run a 30amp breaker?

 

Personally, I'll have a 200 amp sub-panel in my shop.  The house is getting upgraded to 400 in the next few weeks (which sounds huge to me, but the electric company said that's "normal" for Greenwich, CT - he mentioned houses that have 800, 1000, 1200...  yikes).  So I'll have room in the panel to run anything I need, I just don't want to run wire more than once if I can help it!

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==>"up-gauged" - meaning you're running thicker wire?  a 30 amp is 10 gauge wire, right?  You're running 8?

yes

 

==>So even if something has specs that require a 20amp, run a 30amp breaker?

yes. All my 15a, 20a and 30a tools run on 30a outlets/branches/etc. If the tool has a plug, I replace it with a 30a. Why? Experience. I've learned that shops reorganize and after you run the branches, you don't want to do it again... So don't mix, just run 30a for all the 220 outlets... So why not just run 40a or 50a? You can't, per code... Things change when you get to 40a.

 

==>the electric company said that's "normal" for Greenwich, CT - he mentioned houses that have 800, 1000, 1200...  yikes)

Yea, 400a getting more common than you think... Driveway heater (200a), multi-zone AC (120a), outbuildings(125a), etc. My next door neighbor has a 3000sf and an 8000sf barn for his antique car collection -- he's got 800a service... Power just gets used... You should see the size of the generators folks are installing these days...

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I think Trip drank too much electrical gatorade. My whole shop doesn't have one 30 amp breaker, and I have a 3hp TS, bandsaw, planer, and plan to buy a 5hp oneida pro DC and that only calls for a 20 amp breaker as well. Hey it's your money and if you wanna buy lots of heavy gauge copper, who am I to say no.

sorry...8 gauge wire in a hobby woodshop is nuts.

Edited by Janello
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==>I think Trip drank too much electrical gatorade

Let's see, we've got 1x3HP, 4x5HP, 2x7.5HP, 1x10HP (or maybe it's 12, I forget), and I forgot, 1x15HP..  It's a mix of 1p and 3p. It was much cheaper to purchase a single big spool of 3c+g and run everything off that than shorter lengths of individual gauges and mix of conductors... Method to the madness...

 

Edited by hhh
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==>I think Trip drank too much electrical gatorade

Let's see, we've got 1x3HP, 4x5HP, 2x7.5HP, 1x10HP (or maybe it's 12, I forget), and I forgot, 1x15HP..  It's a mix of 1p and 3p. It was much cheaper to purchase a single big spool of 3c+g and run everything off that than shorter lengths of individual gauges and mix of conductors... Method to the madness...

s

show off.

 

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==>I think Trip drank too much electrical gatorade

Let's see, we've got 1x3HP, 4x5HP, 2x7.5HP, 1x10HP (or maybe it's 12, I forget), and I forgot, 1x15HP..  It's a mix of 1p and 3p. It was much cheaper to purchase a single big spool of 3c+g and run everything off that than shorter lengths of individual gauges and mix of conductors... Method to the madness...

 

Yeah, but you're referring to YOUR shop...Not the average shop. Big difference.

If I were Trip and had trips tools, I'd run 8ga. Most of us will never see the need or get there. and If we do...we will be building from the ground up with that in mind.

Edited by Janello
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==>So even if something has specs that require a 20amp, run a 30amp breaker?

yes. All my 15a, 20a and 30a tools run on 30a outlets/branches/etc. If the tool has a plug, I replace it with a 30a. Why? Experience. I've learned that shops reorganize and after you run the branches, you don't want to do it again... So don't mix, just run 30a for all the 220 outlets... So why not just run 40a or 50a? You can't, per code... Things change when you get to 40a.

 

so are you saying you rewire all your big tools to a 30A plug ... if they do not already come with one? Just to make it easier to move tools around and always have the correct outlets to use?

 

Edited by bushwacked
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==>so are you saying you rewire all your big tools to a 30A plug ...

As Jenello correctly pointed-out, my shop's a bit funky... So maybe my solution shouldn't be extrapolated too far... But to answer your question, yes... Since the big tools come sans wire/plug anyway, no issue there... The inspector required everything to be twist-lock, hard-wired to a disconnect, or hardwired... He failed me on the first pass... So all the existing plugs had to go anyway... I purchased a spool of SJEOOW, twist-lock devices and rewired where necessary. I passed on the second inspection, but he made me promise to put the router table on a twist lock and move the DC to a dedicated branch...

All things considered, it took me about three hours to change-over... So it's not like a big deal... But the advantage is that I can move a sander, drill press, whatever across the shop and plug it is without worrying that one tool was 15a, the other was 20a. Why did I do this? My previous shop was 'by the book' -- 15a, 20a and 30a outlets... And every time I moved something, I had a problem... So I did what anyone would... I made some small extension cords with 15a on one end and 20a on the other, 20a on one end and 30 on the other... you get the idea... When I moved to a new shop, I promised never to do that again... So I wired all 220v to 30a outlets...

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I think Trip drank too much electrical gatorade. My whole shop doesn't have one 30 amp breaker, and I have a 3hp TS, bandsaw, planer, and plan to buy a 5hp oneida pro DC and that only calls for a 20 amp breaker as well. Hey it's your money and if you wanna buy lots of heavy gauge copper, who am I to say no.

sorry...8 gauge wire in a hobby woodshop is nuts.

I agree. I ran all 20 amp for all 240 and 120 plus one 40a circuit for the dust collector. 

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==>underwater wrecks

Tally's up to five friends lost on wrecks... Three not a hundred feet from where this was taken...

T-1-2.thumb.jpg.c5a813a9ee54b6147c8779aa

 

But it'll be the cave's that get me: You don't come back, we split your gear...

q-1.thumb.jpg.d49d94cdee0281453e54d45de7

 

j-1.thumb.jpg.12cb43f0cd38300bcaf3532cff

Cenote Nohoch

 

My other hobby -- underwater imaging...

Edited by hhh
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==>so are you saying you rewire all your big tools to a 30A plug ...

As Jenello correctly pointed-out, my shop's a bit funky... So maybe my solution shouldn't be extrapolated too far... But to answer your question, yes... Since the big tools come sans wire/plug anyway, no issue there... The inspector required everything to be twist-lock, hard-wired to a disconnect, or hardwired... He failed me on the first pass... So all the existing plugs had to go anyway... I purchased a spool of SJEOOW, twist-lock devices and rewired where necessary. I passed on the second inspection, but he made me promise to put the router table on a twist lock and move the DC to a dedicated branch...

All things considered, it took me about three hours to change-over... So it's not like a big deal... But the advantage is that I can move a sander, drill press, whatever across the shop and plug it is without worrying that one tool was 15a, the other was 20a. Why did I do this? My previous shop was 'by the book' -- 15a, 20a and 30a outlets... And every time I moved something, I had a problem... So I did what anyone would... I made some small extension cords with 15a on one end and 20a on the other, 20a on one end and 30 on the other... you get the idea... When I moved to a new shop, I promised never to do that again... So I wired all 220v to 30a outlets...

OK, I am nowhere near your level of skill/knowledge ... but this just makes sense to me. I do not see why people would not go this route to make it easier on themselves in the long run. This gave me a great idea for when I finally get to start creating my shop once I complete the house renovation ...

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Thanks for all the replies guys!

I don't have any machine purchases in the near future, just want to try to plan ahead before I close up the studs.  A cyclone is probably the next purchase, some time in 2016.

I've already got an 80A sub panel with just 2 breakers in it (for exterior circuits that are almost never used).  I've been planning on running a lighting circuit, a couple of 20A outlets in the ceiling for heaters, several 20A outlets around the shop, and then the 3 220v outlets (basically in areas where I'd get decent coverage for moving machines around).

So far it sounds like I should make the 220v outlets 30A, with the possible question of whether I need a 40A to handle whatever cyclone I wind up getting.

 

HHH - is there an application process for becoming your heir?  A lottery perhaps?

 

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