Wiring for dust collector

[jwvess00]

Hi there!

I was planning on roughing in the wiring for a future dust collector in the woodshop side of the shop but am not sure what I should do.

The dust collector is probably this one or one similar to it: http://www.clearvuecyclones.com/cv1800-series/23-cv1800-lh-single-phase-with-filters.html

That has a 5HP Leeson motor, 1PH, 240V. The installation book for the dust collector says it requires a 30A breaker. I don't know the model number of the motor they use so I don't know what's on the motor plate. I'm told that it's a real 5HP motor, not "5HP peak" or some such, so it will be hard-wired.

When I read 30A breaker, my mind went to NM 10-3, but a bit of Google searching left me questioning that. I don't know either the motor plate data or the NEC well enough to know if NM 10-3 is sufficient or if it had to be 8-3 (I doubt I *need* 3 conductors plus ground but I don't know for sure so if I'm running NM that's what I'd get).

That's when I realized I'm not sure how to secure NM 8-3 cable. I've never seen a staple that big, and I'm an electrical engineer, not an electrician, so I don't do this as a trade. Dad's a retired electrician but that was for a manufacturing plant, not residential, so most of the wire he pulled professionally was all in conduit.

I don't know when I'll buy the dust collector -- may be later this year, or possibly some time next year.

My original plan was to run the wire from the panel up through the attic space (since it's not yet insulated, that's coming hopefully within a month as soon as I find a contractor), then down into the shop wall and into a surface-mounted box. From there I'd run conduit or armored cable to the unit itself. It's probably a bit more than 40 feet from the panel, up to the attic space, across the shop into the woodshop, and down to where I'll be mounting a box for the connection.

Questions:
1) If I ran NM through the attic, what size? If #8, how do you secure it to the framing, and is there any special rules on spacing?

2) If I use conduit, I assume all sorts of other questions come up but the run would be about 50'-75', and would probably be the only circuit in the conduit (max, maybe one other but I doubt it). What wire size would that be?

 

[wyliesdiesels]

Motor wiring low down:

Over 3HP needs to be hardwired

Wire is sized @ 125% NEC FLC- which is 28a
Breaker is sized @ MAX 250% NEC FLC

For your 5HP motor this means #8 NM-B(#10 is limited to 30a) or #10 THHN(which requires conduit)

If breaker panel is NOT within sight of motor or farther than 50' then a disconnect is required.

U only need */2 with grd conductor cable unless there is 120v controls.

There is staples for NM-B and nails for the larger sizes

NM-B needs to be stapled every 4.5 feet and within 12" of a j box.

Where the cable enters the panel u need to use an NM-B cable clamp.

If u will be running multiple circuits in conduit u may have to derate them so keep that in mind. Running wire in the attic requires derating for the heat as well...But if u use #8 NM-B that shouldnt be an issue since its a little oversized...

 

[pattenp]

Since the wiring instructions call for a 30A breaker then you only need #10 wire. I wouldn't get into the weeds over whether the motor is truly 5hp.

 

[MTW]

Sizing A Feeder for 5HP 230V 1Φ Motor

NEC sizing 5HP 230V 1Φ
28FLA (from 430.248) x 1.25 required min adder = 35A min circuit size
35A wire rating required, (from 310.16)
Romex 60C rated #8AWG good for 40A
THHN 75C rated #10AWG good for 35A (used with conduit)

If it were me, I would use 1.50 as the multiplier, 1.75 is the maximum allowed
28A x 1.5 = 42A med circuit size
42A wire rating required, (from 310.16)
Romex 60C rated #6AWG good for 55A
THHN 75C rated #8AWG good for 50A

Your nameplate Full Load Amps are likely going to be lower due to a 3600 RPM (2 Pole) motor, but the NEC makes no distinction for this.

If you want to have a copy of the NEC to look for yourself.
2011 NEC PDF

MTW Ω

 

[David C]

Can you all discuss this in a little more detail?

I get it that a 3Hp motor requires #10Ga wire and a 5Hp motor requires 8Ga wire.

What is the appropriate wire size when the equip. mfg states that it is a 5Hp motor that draws 30A as noted by the OP.

Does the motor name plate provide the design amperage?

MTW, Can you elaborate on the multiplier, I get it that it is a type of safety factor but there appears to be some discretion in the multiplier value. Why be more or less conservative? What does that buy you. Is it correct to imply from your second to last paragraph that wire size design is based upon nameplate motor Hp?

 

[wyliesdiesels]

NEC sizing 5HP 230V 1Φ
28FLA (from 430.248) x 1.25 required min adder = 35A min circuit size
35A wire rating required, (from 310.16)
Romex 60C rated #8AWG good for 40A
THHN 75C rated #10AWG good for 35A (used with conduit)

If it were me, I would use 1.50 as the multiplier, 1.75 is the maximum allowed
28A x 1.5 = 42A med circuit size
42A wire rating required, (from 310.16)
Romex 60C rated #6AWG good for 55A
THHN 75C rated #8AWG good for 50A

Your nameplate Full Load Amps are likely going to be lower due to a 3600 RPM (2 Pole) motor, but the NEC makes no distinction for this.

If you want to have a copy of the NEC to look for yourself.
2011 NEC PDF

MTW Ω

The wire ampacity chart changed to 310.15(b)(16) in the 2011 code cycle!

And 150% FLC is way overkill...

Can you all discuss this in a little more detail?

I get it that a 3Hp motor requires #10Ga wire and a 5Hp motor requires 8Ga wire.

What is the appropriate wire size when the equip. mfg states that it is a 5Hp motor that draws 30A as noted by the OP.

Does the motor name plate provide the design amperage?

MTW, Can you elaborate on the multiplier, I get it that it is a type of safety factor but there appears to be some discretion in the multiplier value. Why be more or less conservative? What does that buy you. Is it correct to imply from your second to last paragraph that wire size design is based upon nameplate motor Hp?

The OP said the breaker is to be 30a NOT that the motor draws 30a...big difference..

By code, wire for motor circuits is sized based on HP NOT motor nameplate amperage. It is done this way so that if say a 5HP motor made by one manufacturer is swapped for a different brand of 5HP motor which has a higher FLA(28a or less) the wiring will still be sized within spec...

 

[David C]

I didn't phrase my question correctly, and thanks in advance for any information.

If I am recapitulating the OP correctly his dust collector installation book says that he is being supplied a 5Hp motor, and that he should use a 30A breaker (all following questions are based upon 240V 1ph current UNO.

For his 5 Hp motor, if he installs a 30A breaker should he connect it to 8 Ga Cu wire? 10Ga Cu wire is good for 30A by my limited understanding. Are you saying that since it is a 5Hp motor he should use 8Ga wire?

Then there is the confusing issue of the 5Hp shop vac, and the like, on a 20A 120v circuit. No one on this site thinks the 5Hp shop vac requires 8Ga wire.

Can you elaborate on these issues? If you have the time and patience you might include code references. I can read these to help me form a better understanding of the issue.

I am not trying to catch anyone out on anything they said. I don't know enough and it is against my nature, and a waste of time, to play gotcha.

Also I am not interested in what a person might get away with though contrary to the code. Over the last several months I have read guys posting that they run their 3Hp motor on a 20A circuit with 12Ga wire and it doesn't trip. Or they use 10Ga wire on their 5Hp dust collector. I am only interested in those installations if they comply with code.

What I hope to get is a better understanding of the code requirements and how to implement them. I have wired my garage with several 30A brkrs with 10Ga wire. I thought that this limited me to a 3Hp motor.

 

[MTW]

1.What is the appropriate wire size when the equip. mfg states that it is a 5Hp motor that draws 30A as noted by the OP.
2.Does the motor name plate provide the design amperage?
3.MTW, Can you elaborate on the multiplier, I get it that it is a type of safety factor but there appears to be some discretion in the multiplier value. Why be more or less conservative? What does that buy you. Is it correct to imply from your second to last paragraph that wire size design is based upon nameplate motor Hp?

1. By the NEC rules, it doesn't really matter what the OEM says is adequate, unless it has been tested as an assembly and listed as such. In which case it will have a label stating the maximum and minimum circuit protection listed right on the specification label along with the agency that did the testing. In 30 years of wiring dust and mist collectors I have yet to see one tested and listed this way. As an example look at most any A/C condenser unit, these are usually testing laboratory listed and marked with the max and min circuit sizes and even differences for using a HACR rated breaker or fuses, some units don't have a listing for fuses, which means there not approved for use.

2. No, normally the only thing you use the nameplate for is for the full load current, to size the overload relay setting for that particular motor. The circuit is sized by the NEC tables, the overload relay is sized by the particular nameplate. In all the discussion above I don't recall seeing anything mentioned about overcurrent (overload relay) protection. This is normally provided by a motor starter with overload protection, usually not supplied by any collector manufacturer as standard, it keeps the cost down, and puts the liability for proper selection on the installer. Using a breaker or fuses for the overload protection is not good practice, which seems to be the consensus here.

3. The multiplier is required by the code for motor loads, 125% is the minimum allowed and goes up to 175% depending on the circumstances. Again this adder is based upon the table values, not the nameplate values. Looking at it from a different view, normal circuit breakers and fuses are only rated for 80% of their marked rating, for continuous loads, which is what a motor load is considered. Same reasoning, prolonged operation builds heat, latent built up heat, affects the operation of protection devices response. They respond differently depending on the temperature. The multiplier is to assure that there is enough capacity for all conditions of operation, be it, starting inrush, multiple starts, reversing, ambient conditions, temporary overloads, sustained overloads (to allow enough time for the downstream overload relay to trip).

As to the advantage of oversizing a circuit? It's not the cost obviously. Less heating of the circuit conductors and connected equipment, the wire acts as a heat sink and dissipator. Better voltage stability during starts or reversals. Less voltage drop on the run, meaning faster better starts and less wear and tear on the motor components, especially the starting circuits on 1Φ motors. Derating used on a larger conductor will still allow enough ampacity to operate the load without hazard of overheating under all conditions of use.

What is derating? Its another requirement to reduce the allowable ampacity of circuit conductors based upon installation conditions. Ambient temperature, number of conductors in a raceway or bundle, installed in insulation, under roof spaces, exposed to sunlight. These all affect circuit heating and the ultimate temperature that the conductors operate at. If I recall the OP was placing the run in the attic, under the roof, in insulation, and considering additional circuits in the same run, not to mention the voltage drop of longer runs. If you don't know how to do the math and look up the values given, the x 1.5 adder provides for some fudging room for a little more money, x 1.25 is a given minimum.

In my earlier post I gave a link for a copy of the 2011NEC, grab yourself a copy and have a read of article 430 which is for motors. The rules for motors are different than for appliances, general use circuits, HVAC, welders, etc.

I stayed away from this earlier to keep on the OP question, but I really wanted to suggest a feeder with a panel for the workshop. I think that this is what he was getting at, with an additional circuit. My guess is, that if there's not enough power present for the collector, the same would apply to the equipment that generates the dust. Running multiple circuits together requires that derating, running one feeder doesn't require the derating for multiple conductors. Besides that it would provide for a diversity of equipment loads, and for easier changes down the road as required. For my time and money it's cheaper to do it right and once, and call it done.

One last side note on collectors. It's a bad idea to use plastic on the collection system, again it's the cheap DIY system, but can be prone to fires. The link the OP gave on the unit in question, even has a plastic cyclone assembly. Plastic collection pipe and cyclones will build up static charges when the material rubs against it. This can build up the static charges enough to cause a spark as soon as the charged particles touches a grounded surface. Picture a nice blue ignition spark inside the collector hosing which is full of fine particulate and a windstorm too boot, it's not a good thing, and I've seen it happen with several shops. The dryer the atmosphere and the more volume of material greatly affects the chance of this happening. You generally won't find any commercially installed dust collection systems using plastic, it will be all metal to reduce the risk of fires.

MTW Ω

 

[MTW]

Here's some snippets from my cheat spreadsheet with some of the tables you might find useful. As pointed out earlier, some of the section references may be old, but the data is still relevant.

David C, Then there is the confusing issue of the 5Hp shop vac, and the like, on a 20A 120v circuit. No one on this site thinks the 5Hp shop vac requires 8Ga wire.

Take a look at 430.248, the NEC for 5HP would require (56A @ 115V) x 1.25 = 70A #4AWG 60C min circuit size). I'll leave it to you as to who is telling the truth here. Going from the table, any motor operable from a 15 or 20A 115V circuit is likely 3/4HP or less.

MTW Ω

 

[David C]

MTW

Thanks for that, I know that your post took some time to prepare. I read it twice and I am going to print it out and read it again along side sect. 430.

If you can find addition time; what is a reversal?


David

 

[wyliesdiesels]

MTW- good point on the overload protection. I assumed it would either be built into the motor(red reset button on end) or that a starter came with the unit but Ive never installed a dust collector...

David C- there was a thread awhile back that disgussed the gross misrepresentation of motor HP ratings on tools such as shop vacs...a gas powered lawn mower company recently got in trouble for doing the same thing...

 

[MTW]

MTW
If you can find addition time; what is a reversal?

Reversing direction of motor rotation. If done while running, pulls more current and for a longer period than a normal start. There is also plugging which is similar, repeated starts to inch up on something, like jogging a hoist, or inching up on something with a machine tool.

These features don't work with single phase motors, they must slow down enough for the centrifugal start switch to reclose before the motor will start in the opposite direction.

MTW Ω

 

[MTW]

When you got a few hours for study, take a look here for doing some calculations.

Mike has some decent material to learn from, and the price is right. He's gotten better over the years presenting some involved presentations. But he's not as sharp as some of the instructors I had. Still a valuable resource for knowledge.

MTW Ω

 

[David C]

Wylie, I knew that my 6.5Hp shop vac was not a true Hp number. What I was asking is if a motor circuit must be designed for the motor Hp, and not the name plate amps; how is it that these peak Hp motors are able to avoid the requirement. MTW provided the answer which is the design is based upon the listing of the assembled device.

MTW, how is motor rotation reversed. I can imagine setting up a test circumstance where you could force a motor to reverse rotation, but how does that happen in a conventional setting. I can't imagine what would cause my table saw to reverse rotation.

Thanks for the you tube URL. I'll take a view. I still remember E=IR and P=I**2/r from my three classes, fields and waves, RLC circuits, and transitor circuits. I forgot most of it though.

 

[jwvess00]

Hi there!

Thanks for the NEC link.

I stayed away from this earlier to keep on the OP question, but I really wanted to suggest a feeder with a panel for the workshop.

That is probably overkill but it is an interesting idea. The whole shop is an 1800 ft pole barn., divided into two rooms -- the auto shop side and the wood shop. The building is fed via a 100A breaker in the house, to a service panel in the auto shop side. The wood shop room is 17x36, and the auto side is 33x36 (that split partly dictated by the location of a window on the front wall -- the previous owner built the building).

The wood shop side has 3 20A 240V outlets now. One is dedicated to the radial arm saw. The other two give me a choice on which wall I want to use the jointer, which is on wheels. All the other equipment is 120V.

For dust collector motor control, that same company sells this: http://www.clearvuecyclones.com/supporting-products/43-electrical-box.html

They use a Fasco H230B contactor in that box to control the motor. I don't think their $200+ box is required unless I want the wireless remote (which is nice). This thread http://www.clearvuecyclones.com/Bullentin/showthread.php?t=954 shows someone using that contactor to run this dust collector.

 

[pattenp]

If you are still scratching your head as to how to wire the circuit for the dust collector, the control you pointed to is 30A and uses a Nema L6-30 outlet to plug in the dust collector. So use #10Cu on a 30A breaker.

 

[alfredeneuman]

The dust collector is probably this one or one similar to it: http://www.clearvuecyclones.com/cv1800-series/23-cv1800-lh-single-phase-with-filters.html

The installation book for the dust collector says it requires a 30A breaker.

It also says on the assembly instructions page online that the motor draws 20.8 Amps.

#10s on a 30 amp breaker would be plenty

 

[ard]

My shop is conventional stick framing and drywall, but I wired it with EMT for everything. Switches, lights, receptacles, fixed stuff (dust collector, welders, saw, jointer, planer)

just ran pipe to a spot, figure out wire later. 3/4 for rceptacles, 1/2 for lights, 1" for everything else.

Not sure what OPs situation is, but a run or two of 1" could 'future proof' you for a few upgrades later....