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Table saw + welder plug / wiring question

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Forum topic by kyngfish posted 08-06-2020 04:05 AM 682 views 0 times favorited 38 replies Add to Favorites Watch
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kyngfish

115 posts in 937 days


08-06-2020 04:05 AM

My delta Unisaw runs on 240 volts and 20 amps. 3 hp. I just got a welder. It says max input is 24.8 amps when running at 200 amps. It has a 50 amp style plug. I do not need yet another 240 plug. I already have a direct 240 connection at the compressor (separate 40 amp breaker and 8gauge wire) and a plug at the table saw and none of these things including the welder will run at the same time (maybe compressor very rarely). Question is – is there any harm in wiring the table saw with a 50 amp plug – switching the breaker from 20 to 30 amps (currently has 10 gauge wire) and running the welder at the same plug as the table saw?


38 replies so far

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therealSteveN

6241 posts in 1422 days


#1 posted 08-06-2020 04:45 AM

Your average 3HP Cab saw will run all day on a 20Amp 220 line.

Welders are all over the place. This is a good read for you about the welder.

If your max is 24.8, I’d suggest at least a 30 Amp line, but read the manual and make sure. If the plug is for a 50, that is probably for a good reason. I have had 6 stick welders over the years with 200 or more Amp outputs, and all of them needed a 50 Amp input.

I should add my current welder is a Hobart 210 stick, and it’s on a 50Amp breaker of it’s own.

I didn’t see any smoke coming out of your part of the thread, so probably no fire…. :-)

-- Think safe, be safe

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kyngfish

115 posts in 937 days


#2 posted 08-06-2020 05:02 AM

Yeah I’m just wondering if there’s any risk to the saw running on the same circuit as the welder Which needs that 30 amp breaker. (but not at the same time) – I think I would need to run 6 or 8 gauge wire.

The manual for the welder only says 24.8 amps. That’s it.

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MrUnix

8211 posts in 3046 days


#3 posted 08-06-2020 05:03 AM

Yeah, I’d check the manual for your welder to see if it specifies breaker size… I know on my Millermatic 210, it specifies 27A max input, but recommends a standard 40A breaker (or 30A time delay). I went ahead and installed a 50A outlet because I also had the need to provide an RV hookup once every few years. The Unisaw uses the same outlet as well, but only one can be plugged in at any given time. Has not been an issue at all. If your welder can get away with a 30A circuit, then upping the breaker and running both off the same outlet (one at a time) shouldn’t be a problem. Just plug in whichever machine you need to use at the time.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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Madmark2

1604 posts in 1436 days


#4 posted 08-06-2020 05:12 AM

I think what you’re doing is against code. Ibewjon will give a reading please.

At the voltages and current you’re working with errors lead to combustion. Get a pro to wire it. Put all three on separate, appropriately sized, independent circuits.

-- The hump with the stump and the pump!

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kyngfish

115 posts in 937 days


#5 posted 08-06-2020 05:31 AM


I think what you re doing is against code. Ibewjon will give a reading please.

At the voltages and current you re working with errors lead to combustion. Get a pro to wire it. Put all three on separate, appropriately sized, independent circuits.

- Madmark2

Asking a question is against code? To be clear I was asking three questions. Can I change the plug head on my table saw? And given that the circuit already has ten gauge wire – can I switch the breaker? And change the input plug on that circuit to match.

A ton of people immediately react to any electrical questions as though I’d already started a fire.

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CaptainKlutz

3586 posts in 2342 days


#6 posted 08-06-2020 10:34 AM

1)Yes, TS can use any plug configuration you want: as long as it is rated for FLA current AND you never unplug the TS while it is running.

If you plan to use the plug as disconnected device while under power, NEC code requires it to be rated for 3HP motor. Since different mfg have different HP ratings for plugs based on contacts inside; recommend to consult a professional for your plug selection. Last I checked Hubbell rates their L6-30 & L14-30 at 3HP, while the L6-20 & L14-20 are only rated for 2HP. But you should verify if this is still true.

2) Maybe you can change the breaker to 30A with 10AWG wire?
The breaker protects the wire only, and the 10AWG wire is rated for 30A; so 30A breaker will met NEC wiring code. BUT
If the run length from the panel to plug is long (typically 150+ft), you may need to de-rate the wire current rating to avoid excess voltage loss under full load. The need for re-rating depends on the equipment sensitivity connected to the circuit and total run length.
It is also common to see de-rating on wires used for welding equipment, as they are considered continuous loads which raise the wire temp under load for long time periods. Best to use what ever size circuit and wire the mfg of you welder recommends.

3) Yes, you can change the 30A circuit to use any receptacle configuration that is capable of supporting the 30A current and/or rated motor HP.

My apologies that the answers are not shorter. Electrical code has lots of interacting factors.

FWIW:
NEC Code 430.22 requires that motor circuits be rated for 125% of motor name plate FLA. Some older inefficient 3Hp motors have 17A FLA, which requires a 25A circuit (22A rounded up to next breaker size). If you plan to upgrade to 5HP motor tools in your shop, will need 40A circuit (28A FLA = 35A circuit min) per code.

My Hobart 190 welder only draws 22A max and mfg specifies a 30A circuit, but uses a 6-50 plug.
The straight blade plug drives me nuts for two reasons.
First: Straight blade receptacles are not rated for thousands of insert cycles, more like a few hundred. So any outlet that gets plugged/unplugged can get loose or wear out after a few years. If you plan to have a lot of plug changes, suggest a locking L6-30 style plug will be more durable, as it is rated for thousand+ cycles.
Second: It is really hard to find 6-50 receptacle to make an extension cord. Either end up with a 4” metal box and wall receptacle, or hunting down a Forney #58401 6-50r (only found at welding supply or Amazon).

Most welders have flexible input power requirements. While I don’t recommend this; when I am not pushing max current on welder (1/8” steel or less), mine works perfect on 20A breaker, and will even run on 15A generator output working remote for sheet metal work.

Personally I don’t like to install receptacle with higher rating than wire/breaker, but it is allowed in code. So if you want to use 6-50 that comes with welder on your TS and wall outlet, it will work. In most industrial shops, if the installed plug is rated higher than circuit, then the box/outlet needs to clearly labeled with circuit limitation.
In my shop I use L14-30 and 10AWG wire for my 2-3HP tools and welder. By having the 4 wire L14 plug, I can also connect up a small 120V work light on my 2HP Band saw, and have a mini breaker box on my TS station that allows one plug for both Saw, and 120V outlet for router extension table. It adds some cost in the plugs, but as an engineer I like the flexibility.

Always hire a professional electrician when there is doubt!

#IAMAKLUTZ, not an expert, so YMMV.

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

View Fred Hargis's profile

Fred Hargis

6415 posts in 3341 days


#7 posted 08-06-2020 10:36 AM

If the wire is #10, there’s no reason you couldn’t change the outlet and breaker to a 30 amp. The saw will do just fine as well. You cannot (in case I misread your question) put a 50 amp outlet on the 30 amp circuit.

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

View clagwell's profile

clagwell

293 posts in 640 days


#8 posted 08-06-2020 12:02 PM


Question is – is there any harm in wiring the table saw with a 50 amp plug – switching the breaker from 20 to 30 amps (currently has 10 gauge wire) and running the welder at the same plug as the table saw?

- kyngfish

What you want to do is fine, as long as there’s only one receptacle on the circuit:

-- Dave, Tippecanoe County, IN --- Is there a corollary to Beranek.s Law that applies to dust collection?

View Madmark2's profile

Madmark2

1604 posts in 1436 days


#9 posted 08-06-2020 12:45 PM

Like I said, what you are trying to do is against ELECTRICAL CODE!

Put in three, separate, appropriately sized, dedicated circuits. No plugging and unplugging.

Since you didn’t understand the word ”code” in the context of an electrical question, you obviously don’t have deep understanding of what you’re doing. Hire a pro and keep your fire insurance in force because everything will be up to CODE!

-- The hump with the stump and the pump!

View clagwell's profile

clagwell

293 posts in 640 days


#10 posted 08-06-2020 01:00 PM



Like I said, what you are trying to do is against ELECTRICAL CODE!

Put in three, separate, appropriately sized, dedicated circuits. No plugging and unplugging.

Since you didn t understand the word ”code” in the context of an electrical question, you obviously don t have deep understanding of what you re doing. Hire a pro and keep your fire insurance in force because everything will be up to CODE!

- Madmark2

Apparently you missed my post with the NEC excerpt. What he wants to to is in compliance with code.

-- Dave, Tippecanoe County, IN --- Is there a corollary to Beranek.s Law that applies to dust collection?

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kyngfish

115 posts in 937 days


#11 posted 08-06-2020 01:23 PM


Like I said, what you are trying to do is against ELECTRICAL CODE!

Put in three, separate, appropriately sized, dedicated circuits. No plugging and unplugging.

Since you didn t understand the word ”code” in the context of an electrical question, you obviously don t have deep understanding of what you re doing. Hire a pro and keep your fire insurance in force because everything will be up to CODE!

- Madmark2

Uhhh. That’s paragraph you posted doesn’t say what you think it says. You may want to reread every single post on this thread as punishment. :)

I don’t want to put multiple receptacles on the circuit at all.

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Madmark2

1604 posts in 1436 days


#12 posted 08-06-2020 01:40 PM

Asking a question is against code?

Was what I was responding to. This indicates that the OP didn’t understand the word code in an electrical context and therefore doesn’t have the understanding of what they’re doing.

The high currect outlets are not designed for repeated insertions and removals. You can only put one outlet on the high currect line. Plugging and unplugging is bad practice. Just bite the bullet and dedicate the wiring and be done with it.

 

-- The hump with the stump and the pump!

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kyngfish

115 posts in 937 days


#13 posted 08-06-2020 01:45 PM



If the wire is #10, there s no reason you couldn t change the outlet and breaker to a 30 amp. The saw will do just fine as well. You cannot (in case I misread your question) put a 50 amp outlet on the 30 amp circuit.

- Fred Hargis

Can you clarify the last statement? As far as I understand based on the posts above, the only code rule is that I can’t put a plug on a circuit with a ampere rating LOWER than that of the circuit. So a 50A plug on a 30A circuit is actually totally fine.

Honestly all I’m trying to avoid is having to do a THIRD dedicated 240 circuit for 3 items that never run at the same time. The compressor is fine because according to the install instructions it SHOULD NOT be unplugged. So fine. No plug, dedicated 8ga wiring. 40 amps.

For the table saw and welder, it sounds like i need a 30 or 40 amp circuit. My current 240 20A circuit is already running 10GA wire ~20 ft from the panel. So it sounds like the wiring is OK for 30A. Since my welder just runs 30A, maybe the best solution is a 30A plug and changing the plug head on the welder? Or using an adapter?

Either way – one of the plug heads has to go.

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kyngfish

115 posts in 937 days


#14 posted 08-06-2020 01:56 PM



The high currect outlets are not designed for repeated insertions and removals. You can only put one outlet on the high currect line.

That specific quote is the only helpful thing you’ve contributed to this thread. If you stick to statements like that maybe people would listen to you. The first, I didn’t know. The second, I did know, and wasn’t what I was asking. Also, according to other posts, it sounds like this is solvable with a locking plug rated at the correct amperes.

As far as your preference of plugging or unplugging – that’s preference, not code.

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clagwell

293 posts in 640 days


#15 posted 08-06-2020 01:59 PM


You can only put one outlet on the high currect line.

- Madmark2

Why not? It’s allowed:

Just a bit more restricted on receptacle ratings.

-- Dave, Tippecanoe County, IN --- Is there a corollary to Beranek.s Law that applies to dust collection?

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