ZRX61
Well-known member
What size breaker ya running?
Question for everyone running a 60 gal/5-6.5hp compressor...
- Thread starter ZRX61
- Start date
454ragtop
Well-known member
I got a real one, Baldor true 5 HP, on a 30 amp breaker.
Jim
Jim
pault28
Well-known member
Same here.
Now are you talking a real 5-6.5HP motor, or a sears special 5-6.5hp motor?AKA what is the amp rating on your motor?
I'm on a 40amp IIRC. A bit over kill, but it was repurposed so.
Devilbis 6.5.. yanno, the ones they were forced to change the labeling on...
motor appears to be 15amp.
Yea, that is more like a 3.5-4 HP motor. A 30amp should be more than adequate for you.
RCStocker
Well-known member
First of all you can not run anything larger than a 5 HP. motor on 220V. It is impossible. That is all that it calculates out to.
Look at the motor. Look at the amps and you will have your answer. Remember 220V is only 2-110 V lines. It takes less power to run 220V motors. The size wire you run to your compressor is determined by the length of the run of wire and the amps it draws. You can easily find the charts on line so I will not take the time to look it up.
There are 3 ways of figuring Horse power. Companies over rated motors. Sears was one of the worst offenders. The government put a stop to it.
110 V can only run a 2HP. motor. If you see a shop vac that says 5 hp. they are full of bunk, and bull spit. Hope this helps.
Look at the motor. Look at the amps and you will have your answer. Remember 220V is only 2-110 V lines. It takes less power to run 220V motors. The size wire you run to your compressor is determined by the length of the run of wire and the amps it draws. You can easily find the charts on line so I will not take the time to look it up.
There are 3 ways of figuring Horse power. Companies over rated motors. Sears was one of the worst offenders. The government put a stop to it.
110 V can only run a 2HP. motor. If you see a shop vac that says 5 hp. they are full of bunk, and bull spit. Hope this helps.
sberry
Banned
Where did you learn this?
Now are you talking a real 5-6.5HP motor, or a sears special 5-6.5hp motor?
I'm on a 40amp IIRC. A bit over kill, but it was repurposed so.
Sears has what they call "ILS" motor ratings, meaning, if lightning strikes the motor, it will produce the rated horsepower.
JDon99
Well-known member
I don't know where you got this info but it's wrong.
Baldor sells single phase motors up to 15hp.
http://www.baldor.com/products/ac_motors.asp
You mean the 5.0HP shop vac motor won't pull the same amperage as my 5HP WEG motor on my IR2475 compressor with 30amp breaker?.....haha!
Reminds me of years ago when lawnmower manufacturer's kept up-sizing the HP ratings on their Briggs & Stratton engines. I think they they were up to about 6.5HP by the time regulators stepped and cracked down on it for false advertising. Now they rate the engines in lb-ft of torque!
Reminds me of years ago when lawnmower manufacturer's kept up-sizing the HP ratings on their Briggs & Stratton engines. I think they they were up to about 6.5HP by the time regulators stepped and cracked down on it for false advertising. Now they rate the engines in lb-ft of torque!
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pault28
Well-known member
Mine is a 5hp...23 amps with 10 gauge wire and a 30 amp breaker.
Power loss (resistive)= I squared X R
At 220V current running thru the wiring is about half and resistance is the same. That means less resistive loss in the actual wiring.
James_B
Well-known member
30A should be fine.
That being said, I was running my 5HP compressor on a 50A breaker, as it was normally plugged into the NEMA 6-50R socket that I installed for my welder. If I needed to use the welder, the compressor got unplugged.
That being said, I was running my 5HP compressor on a 50A breaker, as it was normally plugged into the NEMA 6-50R socket that I installed for my welder. If I needed to use the welder, the compressor got unplugged.
sberry
Banned
The only real thing is the recept isn't motor rated that high. It is something that doesn't really scare me, I am sure the reason is well founded. I do it, although my main comp is 3 and the breaker is off to the 5 so its not gross error.
Running from one recept can be done,, I am not a fan if I can help it unless its really temporary. I was in a building the other day where the power was really makeshift, green acres and the sorry thing was it had been like that a long while and didn't really need to. I am slowly converting any boogers over but equipment gets it own wire especially if its part of the infrastructure.
ok, plan is 30ft of 10g wire.
& just to muddy the waters a bit.. I may make up a couple of pigtail adaptors so I can run my mig, tig & plasma cutter on the same circuit if the need arises...altho I doubt the circuit would handle them running max output (MM210, Syncrowave 200 & Spectrum 375)
Pity my 40A/250V/10,000W extension cord wasn't 10ft longer, then all I'd need for the compressor would be the pigtail adaptors.
& just to muddy the waters a bit.. I may make up a couple of pigtail adaptors so I can run my mig, tig & plasma cutter on the same circuit if the need arises...altho I doubt the circuit would handle them running max output (MM210, Syncrowave 200 & Spectrum 375)
Pity my 40A/250V/10,000W extension cord wasn't 10ft longer, then all I'd need for the compressor would be the pigtail adaptors.
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James_B
Well-known member
I had no option.
When I fitted the 6-50R socket for the welder, it used the last 2 vacant breaker positions on the 200A/40breaker panel. When I got the compressor, it was a case of fit the compressor with a 6-50 plug or have no high capacity compressor. Even those 2 breaker positions disappeared when I rewired the kitchen to bring it up to code.
Our eventual solution was to get a 200A/64breaker panel and have it installed ... but we sold the house before the installation happened, and the purchasers got the new panel for future installation.
bsaint
Well-known member
You need to use the service factor of the motor to figure into your current equation then multiply it by 1.5 to size the breaker. Or you can just ask here 
Charles (in GA)
Well-known member
You have spouted this before, and it is totally incorrect. Please quit misleading people with your mis-information.
First off, it is generally accepted as 240v, with the nominal number being 230v. 220v is a thing of the past, hasn't been common in the past 30 to 50 years.
Second, you can run virtually any size motor on 240v if you have a large enough amperage circuit. I own a 7½ hp compressor, a true 7½ hp, draws something like 33 amps running. NEC tables show a 7½ motor on 230 has a FLC of 40 amps, and those tables tend to err on the high side to allow for the most inefficient motors, and at 240v the amps will be a little less anyhow.
You can buy compressors with single phase motors up to 10 hp but be prepared to have a good electric system to supply them.
If it is "impossible" to run a motor greater than 5 hp on "220v" then why does the NEC table 430.248 "Full Load Currents in Amperes, Single-Phase Alternating-Current Motors" bother to list motors up to 10 hp?????
It takes the same power (watts) to run a given motor on 120v as it does on 240v, its just that the amperes is twice as much on the lower voltage, thus requiring a heavier wire.
Charles
bsaint
Well-known member
OP, a motor will run more efficient at a higher voltage due to less heat (as the current will be less.) So with less heat you can run a smaller breaker and wire than if you ran a 120v motor saving you some money. I don't know if you were thinking a 120v circuit for your compressor, but I figure Ill throw in that morsel of info.
Its why when I buy a building, it'll be 480v.
Its why when I buy a building, it'll be 480v.
sberry
Banned
You will lose a little down a small wire heavily loaded. hats thee disadvantage of 120 general circuits, very limiting. You can simply carry 2 x the wattage over the same wire at higher voltage with less drop. New technology is helping but costly yet, they can soft start motors and run at 30 hp on rural lines but I think the poco don't cares for much north of 10 hp for a compressor on a rural and residential line.
sberry
Banned
I aint bashing for giving mis info but there are a few things worthy of working on in between the code quotes, we do pretty good with grounding but miss some things about what I call the "reaction" between the current and the wire. It involved V drop and time and duty cycle.
Its best left up to others,, I don't know a watt from an ohm and really only know where 4 wires go but get what some old timers hinted about applied load and why they didn't panic at 2V drop with a circ saw.
Its best left up to others,, I don't know a watt from an ohm and really only know where 4 wires go but get what some old timers hinted about applied load and why they didn't panic at 2V drop with a circ saw.
Picked up a 10/3 6ft drier cord from Lowes & have now wired that to the switch on the compressor so my compressor now has a plug on it. I'm getting closer to having air
Scary find: Popped the cover off the switch on the comp to swap the wires over & discovered that the ground wire wasn't actually connected. It was just sitting there. Compressor was hard wired in at the old place 17 years ago (last 2 years in storage).... I'm assuming it's been like that all along as there was no marks on the end of the wire from it being compressed by the screw that it was sitting next to.. Just like to thank Griffiths Electricians of the Antelope Valley for that **** up.
Scary find: Popped the cover off the switch on the comp to swap the wires over & discovered that the ground wire wasn't actually connected. It was just sitting there. Compressor was hard wired in at the old place 17 years ago (last 2 years in storage).... I'm assuming it's been like that all along as there was no marks on the end of the wire from it being compressed by the screw that it was sitting next to.. Just like to thank Griffiths Electricians of the Antelope Valley for that **** up.
bsaint
Well-known member
On the same token you have to be careful. Some mag starters and cables are only rated for current ampacity @ 250 - 300v. Think SOO Jr cable. In this case even with the same current draw with two different voltage devices, you couldn't not run one at 480v by code if its only on junior SO cable.
Really? If the nameplate on my 1HP motor shows 14 amps at 115v or 7 amps at 230v, please explain how the motor runs more efficient? No matter which way you look at it, the motor still requires 14 amps total, no?
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Others, including myself have gone round and round with RCStocker. I'm not sure if he really is just that stupid or is just trying to stir the pot with his responses. However time and time again he posts inaccurate, down right ignorant information that he just can't seem to understand is incorrect. He is a true example of age and experience have absolutely nothing to do with actual knowledge. That is if his claimed experience is even factual. I think the reason he is not banned is he provides comic relief for many a folks with his obscenely off the wall comments.
Charles (in GA)
Well-known member
His post this time, was, I think, a copy and paste from the last post he made on this exact same subject. If you are just kidding with people, you insert the little round guys
to the right of this reply box, so everyone can see you are kidding.Charles
Charles (in GA)
Well-known member
No, the motor, at 230v would require 7 amps total in your example, but the wattage would be the same 1,610 watts, no matter if 115 x 14 or 230 x 7.
Charles
Durka
Well-known member
EDITED 5/1/2014 -
Sorry, slipped my mind to mention that I was referring to a sub-panel in the garage that I ran from the service in the house, then to the compressor.
Hopefully this should make better sense. Start from the beginning,-
I ran 4 AWG (Copper) in conduit 42" underground to the sub-panel. Code required that I drive two 8' copper grounding rods in succession for; I believe it was an earth ground ? From the sub panel. Here's the sub (did this about 3 years ago), -
View media item 40218
Compressor is on a 60 amp breaker (10 awg copper). I had a couple 20 amp circuits hook up at this time as well. 100 amp service to the sub btw.
Since the motor has it's own protection as sberry pointed out below (post #34)
View media item 39107
Then My 60 amp breaker should be alright ? Overkill, but okay in this circumstance ?
Sorry, slipped my mind to mention that I was referring to a sub-panel in the garage that I ran from the service in the house, then to the compressor.
Hopefully this should make better sense. Start from the beginning,-
I ran 4 AWG (Copper) in conduit 42" underground to the sub-panel. Code required that I drive two 8' copper grounding rods in succession for; I believe it was an earth ground ? From the sub panel. Here's the sub (did this about 3 years ago), -
View media item 40218
Compressor is on a 60 amp breaker (10 awg copper). I had a couple 20 amp circuits hook up at this time as well. 100 amp service to the sub btw.
Since the motor has it's own protection as sberry pointed out below (post #34)
View media item 39107
Then My 60 amp breaker should be alright ? Overkill, but okay in this circumstance ?
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sberry
Banned
This type of motor has its own protection, the wire needs to be large enough to serve the load and the breaker becomes a switch and to protect against short circuit big enough to let the motor start, There are situations where a 60 would be allowed on a 10 wire.
Durka
Well-known member
Thanks, -I hope that this is one of those situations.
sberry
Banned
The load is a pinch above 20, no matter what happens it wont overheat the wire, the thermal on ther motor will open first. When you are doing something like this the breaker cant be above the short circuit rating of the wire,,, (poorly explained and only a generalization) but 14 for a 30, 12 to 50A and 10 at 60.
Having said that,,, although it doesn't make much real difference I also prefer to break closer to the rating and I can,,, and have breakers on hand etc so I put a 30 on. It cant hurt as long as it doesn't trip during starts.
Having said that,,, although it doesn't make much real difference I also prefer to break closer to the rating and I can,,, and have breakers on hand etc so I put a 30 on. It cant hurt as long as it doesn't trip during starts.
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sberry
Banned
You would need a 60 for a 200 synch,,, I don't recall if its 8 or 10 wire @60, but its minimum size is for single circuit in pipe and the other machines are designed to run on 50A max circuits. I am pretty much always plan to run a wire dediucated for these type of machines, 2 circuits here, one for the synch, one for the air and might share the plas and the 210.
Hpozzuoli
Well-known member
89GLH
Well-known member
Ditto.
The former is my guess. I think he's the real deal in terms of being a complete and total idiot. That's why I find him to be so entertaining. He impresses me as being totally serious when he writes the stuff he writes.
Jim C.
Charles (in GA)
Well-known member
Ref: post #33 by Durka..................... not the OP.
Section 430 of the NEC has a table for single phase motor amperages based on hp and voltage. It says that a 5 hp motor at 230v is 28 amps.
The code says to size the breaker and circuit using the table in the code, and not the FLA on the motor, even though it will nearly always be lower. Use the table amps to size the wire, hence, #10 or you could go #8 (depends on the type of wire you are using). To size the breaker, you are allowed to go as large as 250% of the table amps, thus 70 amps max on a breaker, or 175% on time delay fuses, 49 amps, or 50 amp TD fuses. The smaller the breaker, the better, so long as you don't blow it on motor startup. It stands a better chance of protecting the circuit. Since you have a 21.5 amp FLA I would use a 30 amp breaker and see how it works. They are cheap, $7 or $8, so why use the larger one?
Also remember, you must have a disconnect at the compressor if it is more than 50 ft straight line distance, or is not in line of sight from the breaker panel. (code actually says line of sight, however, code defines "line of sight" as out of sight or a distance of more than 50 ft.
In this case, a plug will not suffice as a disconnect, since there are no typical flat blade plugs that are motor rated at more than 3 hp, even though they may be more than the necessary amp capacity.
Charles
Section 430 of the NEC has a table for single phase motor amperages based on hp and voltage. It says that a 5 hp motor at 230v is 28 amps.
The code says to size the breaker and circuit using the table in the code, and not the FLA on the motor, even though it will nearly always be lower. Use the table amps to size the wire, hence, #10 or you could go #8 (depends on the type of wire you are using). To size the breaker, you are allowed to go as large as 250% of the table amps, thus 70 amps max on a breaker, or 175% on time delay fuses, 49 amps, or 50 amp TD fuses. The smaller the breaker, the better, so long as you don't blow it on motor startup. It stands a better chance of protecting the circuit. Since you have a 21.5 amp FLA I would use a 30 amp breaker and see how it works. They are cheap, $7 or $8, so why use the larger one?
Also remember, you must have a disconnect at the compressor if it is more than 50 ft straight line distance, or is not in line of sight from the breaker panel. (code actually says line of sight, however, code defines "line of sight" as out of sight or a distance of more than 50 ft.
In this case, a plug will not suffice as a disconnect, since there are no typical flat blade plugs that are motor rated at more than 3 hp, even though they may be more than the necessary amp capacity.
Charles
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