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Pictures added. Bought a New, old stock, Unisaw. Need electrical advice

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Forum topic by Aaron312 posted 03-16-2020 12:28 PM 1105 views 0 times favorited 29 replies Add to Favorites Watch
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Aaron312

47 posts in 415 days


03-16-2020 12:28 PM

I have been doing some woodworking all my life, but never really had a dedicated shop. Now that I am retired I am going to set up a smallish 300 sq ft shop in my basement and move everything down there. I have had a Ridgid 3650 table saw for years. It is a good, accurate saw and would probably serve my needs just fine. I wasn’t planning on replacing it – until I stumbled upon a Brand New, Never Used, 1998, Made in USA, 3 HP, Left Tilt Unisaw – with a New In Box Unifence and 52” rails. At $500, I thought it was a once in a lifetime deal and I bought it on the spot.

Now my dilema…

I have one 20 amp 110 volt circuit and one 30 amp 220 volt circuit (10 gauge, 2 hots and gound – no neutral wire) available in the basement. I have a Grizzly G0548, 2 HP Dust Collector that draws 9 Amps and calls for a 15 Amp breaker (no reset button on it.) The Unisaw draws 15 Amps and calls for a 20 Amp breaker (it does have internal overload protection.) I don’t think running both machines on one 220 v circuit is code approved, but I think I can legally install a 30 Amp subpanel if I run a separate ground wire back to the service panel (with separate ground and neutral bus bars in the subpanel.)

1.) Is this option of using a separate ground wire OK?
2.) What are my chances of a 30 Amp breaker in the main service panel working with a total of 23 Amps load (thru a 15 A and a 20 A breaker)? I won’t be ripping 8/4 oak all day long! And I won’t use any auto start mechanisms for the DC, so I can start it first and wait a bit before turning the saw on.
3.) I assume I would have to use 10 gauge THHN wire for the ground back to the service panel. Do I have to run that in conduit all the way since it is a single wire? Or can I run it like I would run 12/2 Romex, i.e. stapled to the side of floor joists etc? Existing cable is white-red-black, so I would use the white for neutral and run a separate green wire for ground.

My panel is full, so running another 220 line is not an option. Only other option is to run a new 8/3 w Grnd to a subpanel and that will get expensive enough that I might be better off just selling the Unisaw. Thanks!


29 replies so far

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ocean

228 posts in 1848 days


#1 posted 03-16-2020 12:42 PM

Hire an electrician and do it right. Not worth electrocuting yourself and burning the house down.

-- Bob, FL Keys

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Fred Hargis

6850 posts in 3509 days


#2 posted 03-16-2020 01:32 PM

There’s some pretty sharp sparkies here that will chime…the only i want to say about your saw purchase is YOU SUCK! When you hear the sirens ….run!

-- Our village hasn't lost it's idiot, he was elected to congress.

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HokieKen

16730 posts in 2154 days


#3 posted 03-16-2020 01:36 PM

You can run both of those machines off of your current 30A 230V circuit. AS FAR AS I KNOW. Double check your local code but here the only time you can’t run multiple devices off a circuit is if there is a hard-wired machine on it. Then that machine requires a dedicated circuit.

If you do opt to run a subpanel, I think you have to run a seperate earth ground (as in bury a rod in the ground) not just tie it back to the ground on your main panel. Again, check your local code.

As an aside, if you plan to spend much time in your shop in your retirement, I’d look into upgrading your service panel and running a 60-100A subpanel for the shop. You’ll most likely find that a single 115V and a single 230V circuit are insufficient for your shop.

-- I collect hobbies. There is no sense in limiting yourself (Don W) - - - - - - - - Kenny in SW VA

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HokieKen

16730 posts in 2154 days


#4 posted 03-16-2020 01:36 PM

And oh yeah… YOU SUCK!

;-)

-- I collect hobbies. There is no sense in limiting yourself (Don W) - - - - - - - - Kenny in SW VA

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tvrgeek

1484 posts in 2664 days


#5 posted 03-16-2020 03:14 PM

Your dilemma is you still don’t have a proper riving knife. But yea, a super saw.

If you stagger turn on, you may get away with it but is under-rated and would likely be against code. I believe our code also required dedicated for hard-wire. L6-30P

You saved 2 grand on the saw, do spend it on the power!

View CaptainKlutz's profile

CaptainKlutz

4183 posts in 2510 days


#6 posted 03-16-2020 05:01 PM

+1 Get a couple quotes from electricians. Be safe, not sorry.


1.) Is this option of using a separate ground wire OK?

OK? Maybe.
Yes, you can run a new ground line, add a sub-panel box, and create a 30A sub-panel.

2.) What are my chances of a 30 Amp breaker in the main service panel working with a total of 23 Amps load (thru a 15 A and a 20 A breaker)? I won t be ripping 8/4 oak all day long! And I won t use any auto start mechanisms for the DC, so I can start it first and wait a bit before turning the saw on.

Issue here is going to be start up load, not load while running continuously. The name plate ratings on your motors are couple amp below typical FLA of motors of same size, so it might work in your situation? The unknown factor in FLA ratings is actual voltage. If you line voltage is low, or you have long wiring runs that increase voltage drop, then the actual currents will be higher; and breaker will see more stress.

3.) I assume I would have to use 10 gauge THHN wire for the ground back to the service panel. Do I have to run that in conduit all the way since it is a single wire? Or can I run it like I would run 12/2 Romex, i.e. stapled to the side of floor joists etc? Existing cable is white-red-black, so I would use the white for neutral and run a separate green wire for ground.

- Ground wire is given special rules. It can be a bare conductor. The challenge is code requires common wires from single circuit feeding a common point to be bundled or located in same conduit/raceway. Proper wiring method would be to add a bare/green wire run next to existing romex along the entire length. Stapled near existing staples, and occasionally bundling the 2 wires with electrical tape every couple of feet.

- Is it unusual to see romex with white-red-black wires and not have a ground wire too. Normally electrician will be cheap and uses 10/2 romex with Black/White/Bare when they run 240v circuit with only 3 wires. Have you checked to see if ground already exists, but was terminated at box and hidden?


My panel is full, so running another 220 line is not an option. Only other option is to run a new 8/3 w Grnd to a subpanel and that will get expensive enough that I might be better off just selling the Unisaw. Thanks!

Installing sub-panel offers some freedom beyond your 8/3 thinking. Most times the easiest way to install one is close to main:
- remove existing 2 pole 30A breaker, and replace with 40-50A breaker.
- mount the sub panel next to the main panel to keep wire length short, and allow you to move the existing 30A circuit to new panel. Can use wire nuts to lengthen the wire into new box. Connect the two boxes using conduit and use short lengths of THHN wire.
- run a new 20A 240v 2 pole circuit for dust collector, and use the existing wiring for saw. Running the long wire with only 20A means running cheaper 12/2 wire, instead of heavy wire for entire panel.
Keeping a small sub panel near the main has lowest cost for expensive large gauge interconnect wire and primary cost becomes new circuit wiring.

If any of the above is foreign language to you, please hire an electrician.
Since some cities add/modify local building codes, be sure you are using the applicable code for your location. If you get sub-panel install quotes from couple of professionals, you will quickly learn if your location has special rules.

#IMAAKLUTZ, not an expert.

Be Safe, Not sorry.
Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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Aaron312

47 posts in 415 days


#7 posted 03-16-2020 07:43 PM

Adding a separate ground wire and turning my existing 30 amp circuit into a sub panel was probably a dumb idea. Single strand THHN wire is actually more $ per ft than 12/3 + ground cable! By the time I did all the work and then it tripped the breaker once, I would be swearing.

Good idea on using the existing 10 ga wire to run to the shop, Captain. I hadn’t thought of that. It is a bit to short to reach the saw, so I would have to add a junction box and splice a few more feet of wire in to reach the saw outlet. Not a big deal I guess, but then I would have splices on both ends. It is long enough to reach th DC outlet, so I could use it for that and run a new 12 ga for the saw.

The run from service panel to the shop is 90 feet, so 8 ga does get expensive running it all the way to the shop. Thanks again

View clin's profile

clin

1128 posts in 2011 days


#8 posted 03-17-2020 08:03 PM

If you have to pull any wire, I’d pull a full set of larger gauge wire and bring more than 30 A to a sub-panel located in the shop. Then go from there. Specifics depend on your existing panel and codes. But I’d want to get things setup right once and for all. Run all shop electricity from a sub panel where you can most easily reset a breaker when needed.

-- Clin

View Kazooman's profile

Kazooman

1540 posts in 2968 days


#9 posted 03-17-2020 08:14 PM

I am curious. Can you tell us a bit more about “stumbling” on a brand new 22 year old table saw? There has to be a story here.

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JackDuren

1465 posts in 1975 days


#10 posted 03-17-2020 08:41 PM

What’s on the 30 amp plug?
I have pretty much the same unisaw. 20 amp 12 guage wire. Delta RAS on the same line. Have had both on at the same running a load on only one at a time…

If it were me I’d change the 30 amp to a 20 amp and go from there….

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Aaron312

47 posts in 415 days


#11 posted 03-17-2020 11:36 PM

Yes, there is a story. A local dealer bought several unisaws for their 20th anniversary celebration in 1998. They had Delta custom paint them a gorgeous emerald green (saw, rails, unifence, everything) to match the store’s logo. The owner kept one for himself and sold the others. But he never got around to taking it home. 20 years later, he retired and sold the store. He built a new house and shop and bought a top of the line saw stop for himself. The Delta went with the inventory to the new owners and they put it on the floor for sale. I just happened to walk in at the right moment!

I will post some pictures if I can figure out how.

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Aaron312

47 posts in 415 days


#12 posted 03-17-2020 11:49 PM

I am going to put in a sub panel. I will either run 90 ft of 8 gauge and put the panel in the shop, or do as Captain Klutz suggested and put the sub panel next to the service panel, use the existing 10 gauge wire for one 220 circuit, and just run one 12 ga for the second 220 circuit.

View HokieKen's profile

HokieKen

16730 posts in 2154 days


#13 posted 03-17-2020 11:57 PM

I would strongly suggest you run the subpanel to the shop and run the appropriate size wire for 60A (6 ga IIRC). It’ll cost a bit more now and you may never use it but, I don’t know anyone that sticks with this hobby for an extended period and doesn’t wish they had more power available. Just my opinion but something you may want to consider.

-- I collect hobbies. There is no sense in limiting yourself (Don W) - - - - - - - - Kenny in SW VA

View Kazooman's profile

Kazooman

1540 posts in 2968 days


#14 posted 03-18-2020 12:37 AM



Yes, there is a story. A local dealer bought several unisaws for their 20th anniversary celebration in 1998. They had Delta custom paint them a gorgeous emerald green (saw, rails, unifence, everything) to match the store s logo. The owner kept one for himself and sold the others. But he never got around to taking it home. 20 years later, he retired and sold the store. He built a new house and shop and bought a top of the line saw stop for himself. The Delta went with the inventory to the new owners and they put it on the floor for sale. I just happened to walk in at the right moment!

I will post some pictures if I can figure out how.

- Aaron312


View Kazooman's profile

Kazooman

1540 posts in 2968 days


#15 posted 03-18-2020 12:41 AM

Thanks! That is an interesting story, that makes some sense. The part about “never got around to taking it home” makes me cringe. Not think about bringing a new Unisaw home? That guy must have had one hell of a shop!

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