Unisaw Switch Update

[Sonny]

Re: 4 HP motor install

Spoke to the local motor experts. The standard Unisaw switch is sufficient. He did have and offered to us a switch with the built-in LVC unit, for $254. He said we need a 35 amp breaker and #8 wire. He also said a 5HP motor would require a different switch and larger breaker, also.

Local electrical supply, next door to the motor specialists co., had all supplies we needed. There is no 35 amp breaker, so a 40 amp will do. While there, we spoke to an electricain and he'll do the wiring this afternoon. Electrician recommended a (clothes) dryer cord and outlet box, rather than the cord and outlet Jonas has.

Did any of you have any questions or concerns, that is not covered above? I'm sure I can get more info from the electrician and motor guys.

Sonny

[Sonny]

Okay, another update. Electrician came out and discovered the switch was wired wrong.

Everything we initially had was appropriately sized for the saw, motor, etc. The 12-2 wire was sufficient, the 20 amp breaker was sufficient and the 220 outlet was sufficient.

The saw runs fine. The amp draw is 6 amps at continuous run (according to the electrician and his meter). He said the start-up didn't approach the capacity of the breaker, the switch or any other aspect of the electrical system. He wired it correctly and said we were good to go.

The supplies Jonas bought, mentioned earlier, can be returned, since they were beyond what was needed. We may be able to return the #8 wire, also, or at least possibly get a partial refund, since it was cut from a roll.

Sonny

[Swingman]

Nothing like "boots on the ground" ... even the motor expert and electrician didn't agree until someone got some hands-on on the ground.

You sure that motor is not 3 HP? ;)

[Larry Jaques]

I hope he taught you and Jonas how to read a VOM so you can avoid that next time.

That nameplate amperage for the other motor was 17.something, so I figured it might be OK as-is.

What'd he nail you for, chargewise?

Good luck with that.

-- Progress is the product of human agency. Things get better because we make them better. Things go wrong when we get too comfortable, when we fail to take risks or seize opportunities. -- Susan Rice

[Swingman]

The methodology/approach that must be taken into account when answering questions of this nature, sight unseen, is not whether something "works", but whether it will pass an inspection and be in compliance with "minimum standards" as set forth in models like the NEC. To do otherwise is a disservice to the integrity of the advice proffered in a forum of this nature. This fact was clearly illustrated by many of the answers here, as well as the answer provided by the "motor expert".

Let's not fall into the trap of assuming that because something "works", that it is an all encompassing solution that automatically makes others "wrong".

[John Grossbohlin]

Which reminds me of some wiring I found in the basement of my house when I bought it... About 40 feet of old lamp cords were taped together to run a wire across the basement, laying on the hung ceiling, and out through the exterior rim joist and siding to power a dual bulb outdoor flood light. Yes the lights worked but the wire gauge was probably something like 20 or 24, there were a bunch of open air connections, no work box at the fixture, and no ground.... The wire was also really warm while the lights were on. Needless to say, though it worked I ripped it out immediately.... ;~)

John

[Swingman]

I mentioned it here in past about coming close to a catastrophe some 23 years ago when my then 4 year old came into the garage one afternoon to tell me about the "pretty lights" in the living room.

The "pretty lights" was a fire in a wall that started because someone 30 years earlier had added a receptacle on the opposite side of the same wall and simply twisted the wires together inside the wall with electricians tape.

It worked, and lasted 30 years ... just thank gawd it was 1:30 in the afternoon, instead of the morning, that it finally failed. Our bedroom was on the opposite end of the house from that wall, which was one room away from our daughter's bedroom.

I decided at that time that in the future I would inspect all electrical work myself, not take anything for granted, and that any work of that nature I did personally would be on a fully informed basis and be in compliance with applicable codes ... no exceptions.

[Sonny]

Jonas was prepared to pay them, but the electrician said their office would bill him. For a quick job as this, I was surprised payment couldn't have been settled then. I'm interested in what may be charged, also.... about an hour's time.

The electricain who ran the underground wire and wired my shop subpanel charged me $45. The 6" underground PVC pipe was already laid for the wire run, so the electrician didn't have to do any digging or such, etc. and I had all the supplies he needed.

When at the electrical supply, we met the electrician who was eager to help, so was hired at that time. According to our info, specs, etc, he told us what was needed, as the salesman wrote down his recommendations. Later, at Jonas' shop, the electrician phoned the supply co. and explained we didn't need most of the items, after all. Jonas is to speak with Darrell, one of the supply suprevisors, about the wire refund. Jonas bought 40' of wire, so for that guage, maybe

40' is readily reuseable and he may get whole or partial refund. Otherwise, Jonas has no use for that size wire. I guess it depends on the circumstances, for some refunding, as this, and, it seems, the electrical suppy is willing to try to accommodate its customers, when possible. *Sounds like good customer service, to me! Seems the electrician and the Supply Co have a good working relationship, also, since it only took a phone call to make the arrangements for the possible refund.

Sonny

[Larry Jaques]

Absolutely true...if he were doing wiring, but this was a switch on a table saw, with (I assume) a pigtail going to an existing outlet. How often are those inspected? I'd probably have replaced those breakers, too, but he hired the electrician most of us suggested.

My train of thought was "It should work safely", I found out that it did, and then I thought "Good." No neeners or exclusionary thoughts entered my mind here, nor did any show up in my post, so why did they there, Swingy? Puzzling.

-- Progress is the product of human agency. Things get better because we make them better. Things go wrong when we get too comfortable, when we fail to take risks or seize opportunities. -- Susan Rice

[-MIKE-]

False inference.

[Sonny]

Slight correction: There was no existing anything regarding wiring for this saw, except that the new motor came wired. Jonas' dad had a friend with this saw in an old shop. The saw was given to Jonas. We did some cleanup and check some alignments & other conditions of the saw, before considering any wiring. All wiring, from the breaker panel to and including the switch is new. *The saw is missing the $8.15 flange (large washer) that the blade nut secures the blade with, so he can't install a blade, yet. Jonas has a new Unifence & side table frame (no table top, yet), so that'll be installed next.

Almost all of the major wiring in my shop was done by an electrician. Jonas thought he could do his saw wiring. He's learning his limits, too, but learning, nonetheless.

Sonny

[Sonny]

the term "motor expert"

Once we had our wiring problem, we brought a copy of the motor specs to the local motor experts, Judice Electric Motor Co., and got advice from them, regarding proper wiring and whether the switch was appropriate for the 4 hp saw, relative to the specs. Judice Electric is relaiable, I've had past work performed by them. To the best of their knowledge and charts, they offered their opinion about what all wiring was needed. Then I went to Teche Electric Supply and the sales rep, knowledgeable, also, helped us. The electrician hired was standing there and I asked his advice and if he'd come out to do the work.

Karl may have been referring to my reference to motor experts, Judice Electric .... (and (implied?) the other experts, in their turn, in servicing us).

Sonny

[Swingman]

Your phrase, not m > The standard Unisaw switch is > sufficient. He did have and offered to us a switch with the built-in > LVC unit, for $254. He said we need a 35 amp breaker and #8 wire. > He also said a 5HP motor would require a different switch and larger > breaker, also.

Some folks just don't bother to read before they jump.

[Lew Hodgett]

RE: Subject

NEMA general purpose motor ratings are 3HP & 5HP.

4HP would be a definite purpose motor.

A table saw is considered a general purpose application.

The thermal-magnetic c'bkr for a motor application is chosen for it's ability to handle the inrush current of the motor.

For a 3HP, cap start, cap run, 230VAC, 1 PH motor, a 2P-30A c'bkr is req'd which then requires #10 AWG copper wire between c'bkr and motor.

For a 5HP, cap start, cap run, 230VAC, 1 PH motor, a 2P-40A c'bkr is req'd which then requires #8 AWG copper wire between c'bkr and motor..

For either of these configurations, only the wiring is protected.

An overload relay is req'd to protect the motor windings.

The lowest cost way to wire between c'bkr and motor is to use a 25 ft molded cord set with receptacle clipped for direct wiring.

Lew

[Max]

Did the electrician measure that amp draw under load? If you're ripping a piece of 2" thick maple you might find that the current draw is much higher. I find it hard to believe that a *5* HP motor only draws 6 amps. I have a 3 HP that draws more than that. On 220V. It's not a Craftsman motor is it? (just kidding)

[Bill]

If it was "cut from a roll", it would surprise me if it was eligible for return, rather like a cut from a roll of carpet. I guess it just depends how saleable it is and where you bought it, etc. etc.

[Lew Hodgett]

------------------------------- The sign behind the counter usually reads, "No returns on cut wire", or something similar.

At least in all the years I was associated with electrical distributors it did.

Lew

[Larry Jaques]

I sit corrected. (too lazy to stand)

It's legal in most states to do your own wiring, so I always have. There are lots of books which would help Jonas on his quest.

The library is always my first stop, to see if they're worth reading. I sometimes go through 3 or 4 to find a good one. When I find one I like, I usually buy it.

-- Progress is the product of human agency. Things get better because we make them better. Things go wrong when we get too comfortable, when we fail to take risks or seize opportunities. -- Susan Rice

[Swingman]

Your point goes right back to my contention that because something works doesn't mean that it is the optimum solution.

Makes you wonder how the "motor experts" at Judice feel, based on their knowledge of motors, about being so far off base with the electrical design requirements from what the electrician determined on site?

And Lew's assessment, based on many years in the business, was certainly in line with the "motor experts". In over ten years of watching his participation here, I've not seen one single instance of his electrical advice when it comes to electrical design requirements being nothing but absolute spot on.

I gotta admit to a raised eyebrow about the final solution since I've known so many numb nut electricians in the construction business, but the proof will be in the pudding and it could be be just fine for the intended use, which is all that matters in any event.

I will say unequivocally about the final solution for a cabinet saw, providing it is indeed a 4HP motor: "not in my shop".

[Sonny]

No. A blade can't be installed at the moment because the flange, to help hold the blade in position, is missing. If the breaker trips when a load is applied, we can easily up the wire and breaker size.

The motor is 4 hp and the spec sheet does indicate it is for a saw.

Sonny