Wire Size for Kewanee Elevator Motor

MFan

Member
I've got a 46 foot Kewanee 500 elevator with an electric motor. It's going to be used in a couple of places to load the hay mows, so I'm wanting to run wire in the barns to convenient outlet locations.

Motor is from a silo unloader, 5 HP, 240V (single phase), 26 amp. It's got a motor starter on the side. I'm thinking of running 8 AWG stranded from the main box in each barn to the outlet location (probably 60-80 feet run). I'd have a 30 amp shutoff switch by outlet. From the outlet I would use a heavier extension cord, 10 gauge, out to elevator motor.

Any thoughts from the electrical gurus on this? I know that 10 AWG is rated for 30 amps, but I'd rather err on the side of caution and use a larger wire size.
 
I did not take time to do the calculations, but if the run is not more than 80 feet, your plan should be fine.
 
M Fan, always glad to see a person ask questions and try and do things right. You asked for it so here are my comments: Wait n see, electrical or legal questions usually bring out the most opinions of any topics here lol and I enjoy and love reading every one.........


A) "I'm thinking of running 8 AWG stranded from the main box in each barn to the outlet location (probably 60-80 feet run)."

I did this in a hurry so no warranty but for

8 AWG Copper,,,,,,,,,240 Volt Single Phase Motor,,,,,,,,,,,80 Ft run,,,,,,,,,,,26 Amps,,,,,,,,Looks like the voltage drop would be 2.686 volts or 1.12% which is acceptable and its something Id definitely (if my calculations are correct???) do versus using only 10 Gauge. But do as you please, I'm ONLY here to offer help and suggestions, but NOT tell others what to do.


B) "I'd have a 30 amp shutoff switch by outlet. From the outlet I would use a heavier extension cord, 10 gauge, out to elevator motor."

Id be sure the 30 amp switch is BOTH in sight of and within 50 feet of the elevator. Our shop always used lockable switches so the electrician could padlock the switch when he was working downstream of it. That's kind of how they are made as a safety precaution.

C) "From the outlet I would use a heavier extension cord, 10 gauge, out to elevator motor. "

Okay here's the deal and dont anyone have a calf yet: TRUE 10 Gauge wire (subject to insulation and enclosure and temp etc etc) is generally rated for 30 amps.............TRUE 26 amps is less then 30.............TRUE (Billy Bob) 10 gauge will work and suffice fine. I just have to say, however, when I was an AC Power Distribution Design Engineer I perhaps "over engineered" or was "over safe" or "over conservative" lol and I didn't prefer (when and where possible) to have a continuous load of over 80% of a conductors rated ampacity i.e. I didn't prefer to have over 24 amps continuous in 10 gauge wire BUT THATS JUST ME....... (But see below regarding true ampacity

HOWEVER if you look deep at wire ampacity charts the insulation class and enclosure and ambient temperature and jacketing all contribute to the safe rating, and if used outdoors in free air the ampacity can be higher then if the conductors are say enclosed in conduit or buried or in free air etc etc etc.

D) You mentioned a "motor starter" I take it theres proper thermal overload protection for the motor ???

E) Any overcurrent protection for the conductors FROM the switch TO the elevator will be sized, of course, to match the wires ampacity. That could be fuses or circuit breakers (TWO POLE OF COURSE) such as a two pole fused safety switch (Id use like Class KF Dual Element Time Delay fuses to allow motor start up if I recall correctly, been a while sorry) versus a non fused safety switch if that's the overcurrent protection location. If not already so equipped with proper thermal overload protection, you know they make Combination Starters which suffice for BOTH the safety disconnect PLUS have the starter contactor and heaters/thermals all built in to a single unit.

F) As I'm sure you're already well aware that 240 volt (Only 240) single phase branch circuit requires the two Hot UnGrounded Phase Conductors L1 & L2, PLUS the safety Equipment GroundING Conductor which IS VERY IMPORTANT in that outdoor metal device application !!!!!!

NUFF SAID

Best wishes, keep safe with outdoor 240 volt equipment, the life you save may be yours or your family.........

John T
 
John T, thanks for the reply. Some follow-up questions.

For your item D): by motor starter I'm referring to the large, square box on the side of the motor. I assumed it was for high torque starting. Is there a better or more correct name for it?

What do I need to check to make there is proper thermal overload protection?

Item E): Do I need 30 amp time delay fuses at both the main box where the branch comes out of, and at the safety switch? Or just time delay out by the switch?

I like to include as many shutoffs as possible in a circuit to allow for work on the system while keeping lights, etc., on for seeing what I'm doing.
 
A) "For your item D): by motor starter I'm referring to the large, square box on the side of the motor. I assumed it was for high torque starting. Is there a better or more correct name for it?"


1) THATS NOT JUST A BOX WHERE CAPACITORS ARE LOCATED IS IT??????????? I ask cuz you mentioned High Torque Starting. Take a Look See??

2) Its NOT just a wiring junction box is it????

NOTE !!!!!!!!!!!!!! I'm more used to seeing capacitors or junction boxes on the side of a motor then a Starter. If I were to place a bet Id doubt its a starter BUT HEY I HAVE BEEN WRONG BEFORE LOL Are there any push buttons or red re sets or switches of any kind on it???

3) I cant say from here just whats in that square box, perhaps some of the fine more hands on more recent in the practice (I been retired since 1991) electricians can and/or even post some pictures for you???

That being said, A Starter consists of a set of Contactors (like a relay) PLUS Thermal Overloads or what are called Heaters. How it works is the heaters sense current and if its excessive the relay/contactor opens up.

Look n see whats in that box??? Is it simply a wiring junction box orrrrrrrrr see if theres what looks like a relay and set of contacts inside there orrrrrrrr Capacitors??????



B) "What do I need to check to make there is proper thermal overload protection?"

See the above LOOK INSIDE THERE. (Capacitors, Relays, Simply wiring???) Note some smaller motors have an internal thermal overload protection device and you see like a red re set push button somewhere on the case GOT ANYTHING LIKE THAT


C) "Item E): Do I need 30 amp time delay fuses at both the main box where the branch comes out of, and at the safety switch? Or just time delay out by the switch?"

Is the "main box" a circuit breaker panelboard or a fuse panel??? You may NOT even need them it depends on the motors starting characteristic and starting torque and start up load. Looks like an elevator would be started empty before grain is added (increasing load) so a regular fuse would work HOWEVER if a regular fuse blows due to excess initial start up current (I doubt if elevator is started empty), then BOTH locations would require them. Often the main panel is a circuit breaker while the fused safety switch is where time delays may or may not be needed. Also, the code allows the use of a larger breaker then normal to allow a motor to start so it doesn't trip provided the motor is overload protected


That's all I have to say about that

John T
 
Silo unloader motor box will contain 2 , 3 or 4 capacitors with start and run functions.
A local motor starter will be required at each supply receptacle.
Don"t plan on plugging the elevator in live and under startup .
10awg would do but 8awg would be better as the code book calls for 32.5 amp minimum capacity.
70 amp non time delay fuse, 45amp time delay fuse or 60 amp breaker. Starter thermal size 30.0amp.
 
JohnT,
This is just for my understanding. If a 5 hp motor is only doing 2 hp of work will it use the full amps, 26 amps?

If my 225 amp lincoln welder is only set on 75 amps will the amp draw on 75 be the same as on 225?

If your answer is no to both questions, shouldn't the person asking the questions measure the current while the elevator is under full load? That may be hard to do unless he has the smaller wire to run a test.

Have a great day and don't eat too much turkey.
George
 

I'm not John T.
George, you make an interresting point. The National Electrict Code charts are designed to protect the wiring and motor. There would be nothing wrong with going smaller to do what you are talking about. But an easier way would be to just put a zero speed switch on it to stop it if it droped below a set speed.

I have a feeling that that large box on the side of the motor is NOT a motor starter but just holds the captors and motor leads.

Waiting to see what John T has to say.


Dusty
 
Mornin George,

Hey, you're a good hand on electrical stuff I bet you ALREADY know this. Sure, as you increase the load on a motor the amperage increases and likewise if you're welding at low amperage she's not pulling as many amps on the welders input.

Without looking back at his post or in general the Full Load Amps (FLA) as best I recall, lol its been a while remember, is the number I used when I designed a motor branch circuit. If I designed for FULL LOAD figures, that should have taken care of it I figure.

Have a Happy Thanksgiving George

John T
 
And here I was waiting to see what the good Dusty Man had to say lol. As you know I'm rusty as an old nail on this having retired in 1991 and rely on you more recent hands on "real electricians" to help me out which yall do and I appreciate it.

I agree its prob NOT a starter but a capacitor or wiring box, that's why I asked if there were any BUTTONS on it???????

QUESTION FOR YA ELECTRICIAN: Those typical two Push Button mechanical type Start/Stop boxes you might see say on the wall next to the motor, did those serve as the Starter with Thermal Overload PLUS the Disconnect method I.E. kind of like a Combination Starter orrrrrrrrr were they the Starter ONLY????????????? and a separate disconnect (safety switch) was ALSO required????

Talk to me my friend and Happy Thanksgiving

John T (like to see you in Florida again)
 

John, I retired 10 years after you, and that was more that 10 years ago, so I'm becoming rusty also.
Those mechanical starters were mostly just a starter and thermal overload. Some may have had a disconnect on them. Maybe some had a lock out on the start button.

On those motors with the large box on them.
They sure were nice to hook up because had so much room to put the wires.
All that I worked on were totally enclosed air over. And that large box had a nice gasket on the cover. And some were aluminum frame.
I soon learned to NEVER install them where that box would be on top. Especially if they were to be used in cold weather. When the motor is running the motor warms up, then when turned off they cool off and draw cold damp air in, then moisture turns to water and runs into the motor, which soon ruins the motor.
So it's best to set the motor so the box is on the side of the motor, and drill a hole or 2 so that condensate can drain out.

John, I don't know if I'll make the Fly Wheelers. Let you know latter.

Dusty
 
Thanks again for all of the info. I took a closer look at the motor and posted a picture of what is inside the side box. Link in this message should take you there.

Looks like capacitors and a reset switch?

That said, will I need an external motor starter for this large of a motor?

More info on motor from name plate:
Century Farm Rated Model K300
FRAME: F215TZ
TYPE: CSF
HP: 5
CODE: J
HZ: 60
PH: 1
RPM: 1725
VOLTS: 230
THERMALLY PROTECTED PM
AMPS: 26
TIME: Cont
AMB: 40°C
SF: 1.00
INSUL CLASS: B
NEMA DESIGN: L

Some of this is pretty basic and already in previous posts, but wanted to list all that they had on the plate.
Photo of Century Motor
 
Line current on an AC induction motor is not linear with shaft HP. PF maybe a lousy 0.4 at 2HP but improve to 0.8PF with the motor at full rated load.
Modern starter plugs are interlocked to prevent plugging in or inplugging while the receptacle is energized.
 
Thanks for the reply. I double-checked the motor last night and the box contains capacitors and a push-button reset(?) switch. To see a picture, use the link in this message.

For the motor starter at each receptacle, would that basically be an ON/OFF switch setup? I'm not that familiar with these larger motors (at least large to me) and not up on all a motor starter does, but trying to learn.
Picture of Motor Box
 
Time for an update based on new info, I was getting lost down below. I'm trying to give you a range of options now BUT AFTER THIS ITS YOUR CALL Any electric supply house can size a starter and thermals and safety switch (use NEMA 3R for outdoor use) and fuses and/or Twist Lock Receptacles and Plugs now, let them figure the rest of this lol

The picture is what we were thinking, capacitors in that box plus what appears to be a thermal overload with reset.


1) I would still prefer a two pole fused safety switch disconnect at each location in sight and within 50 feet of the elevator. If you're running 10 gauge from it to the elevator, Id use a 30 amp regular fuse and in the event it doesn't allow the motor to start (which I doubt), Id use Class K5 Dual Element Time Delay Fuses.

NOTE AS I RECALL a simple female Receptacle at the barn and a male Plug on the cord to the elevator can serve as the "means of disconnection" i.e. A full blown Safety Switch IS NOT NECESSARILY REQUIRED. Id use 30 amp 2 Pole 3 Wire Grounding Twist Lock Receptacles and a matching Plug. HOWEVER if you do that remember the overcurrent protection device in your main panel (that feeds the receptacle) would have to be a 30 amp (for the 10 gauge cord to elevator) even thought you're still running 8 Gauge from the panel to receptacle.

ID STILL WANT A MOTOR STARTER although Billy Bob could start it across the line by just flipping the safety switch to on which may eventually burn n carbon up the switch knife and contacts lol

You could use a cheaper simple ON/OFF two push button mechanical two pole 240 volt starter with thermals (heaters) just size it for the Motors HP and FLA. The electric supply shop could do that.

Such a device could be mounted underneath the Safety Switch,,,,,,,,,,,,,,,,, Or above the Receptacle,,,,,,,,,,,,Or buy a "Combination Starter" which is BOTH a Safety Switch PLUS Motor Starter all built into a single enclosure.

Likely the cheapest yet still legal system would be a mechanical two button On Off starter with thermals and receptacle and Receptacle mounted under it,,,,,,,,,,Next cheapest a fused safety switch with a starter under it but then you still need a recp and plug out to the elevator,,,,,,,,,,,Probably most expensive is a Combination Starter but I haven't priced this stuff in years so no warranty.

This all hinges on a Receptacle and Plug serving as the "means of disconnection" which I think is fine (No warranty however) thereby no safety switch is required, but I would still like a starter with thermals even if the motor still has that built in overload device. A real Billy Bob might rely on the motors overload device and just use a plug and receptacle but I dont like to start a motor by just plugging into a receptacle YIKES lol Heck at least have a knife type safety switch Bubba can throw!!! Better buy a real "starter" dont ya think???

If my prices or NEC (and Plug & Recp as disconnect) are out of whack maybe Dusty Man can straighten me out???

NUFF SAID rest is up to you

John T
 
Thanks again for all the input.

Perhaps this opens another can of worms, but do am I correct to think the ground wire in the circuit needs to be similar size to hot wires.

EXAMPLE: 8 AWG for L1 and L2, 8 AWG for ground?
 
When I designed I just usually specified the same size HOWEVER if you dig deep in the NEC (Mines soooooo outdated) there are some exceptions that permit it to be smaller wire in certain situations, but Im wayyyyyyyy to lazy to look that up lol

John T
 

The plug and receptacle is good for a disconnect. The starter could be mounted on the elevator near to the motor. That way only 1 starter is needed no mater how many different you places you plug in.
You can get 8-2 w/ground cable, not cord to run to the receptacles. Use cord to go to the starter and motor.

Dusty
 

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