Need some help on adding a RPC to my shop. I will be picking up a used 25hp RPC that will power 5 machines in my shop. None of the machines will be powered at the same time. I have a 10HP wide belt, a 7.5hp table saw, a 10HP dust collector, a 5HP shaper and a 1hp feeder. I haven't checked out the RPC yet because I don't have it in front of me, but I was wondering if I should get a separate box with breakers and wire each machine to the box then run one circuit from the box to the RPC? I was planning to run 2 gauge wire from the main panel to the RPC and use the same wire possibly from the RPC to the box that I have the machines wired to. Would that work or is there a better way of doing this?
Could I use 12/3 romex for the 5HP shaper and feeder, then 6/3 for the 10HP sander and the 10HP dust collector and then 10/3 for the 7.5hp table saw?
You don't list voltage, I am guessing you have 240. Yes for the panel for the output of the rpc , each motor needs the proper breaker. 12 ok for the 5 hp. 10 ok for the 7.5. 8 good for the 10. I hope you don't plan to use Romex in place of cord, and cord would be 12/4 or 20/4 because the ground is counted as a conductor, where Romex is 12/3 w/ ground. Romex is not allowed by NEC for exposed usage, and dangerous because romex is easily damaged and not flexible. And there will be 2 machines powered at once, so start the DC first, then a tool. Then the feeder. So actually 3 machines.
You don t list voltage, I am guessing you have 240. Yes for the panel for the output of the rpc , each motor needs the proper breaker. 12 ok for the 5 hp. 10 ok for the 7.5. 8 good for the 10. I hope you don t plan to use Romex in place of cord, and cord would be 12/4 or 20/4 because the ground is counted as a conductor, where Romex is 12/3 w/ ground. Romex is not allowed by NEC for exposed usage, and dangerous because romex is easily damaged and not flexible. And there will be 2 machines powered at once, so start the DC first, then a tool. Then the feeder. So actually 3 machines.
Ok thanks for the reply. I wasn't planning to use romex, but rather 12/3 and 10/3 and 8/3 ect. That has three wires and a ground and it will be in conduit. I will have 240 out of the breaker box and into the RPC. So you are saying that I can have a box on the output of the RPC with a breaker for each machine and the appropriate sized wire going from the box to the machines? What kind of box should I use? A standard 3 phase breaker box with the appropriate 3 phase breakers? Never dealt with 3 phase equipment. The 10HP dust collector is 25amps on 240v so that would get a 30amp breaker and the same for the sander. I would use conduited 8/3 wire going from the 3 phase box on the output of the RPC to the machines. The table saw is 17 amps at 240v so I would use a 20amp breaker and 10/3 conduited wire. Then so on. Does this sound reasonable? Any suggestions on specific 3 phase breaker boxes for this setup? It would need to have at least 10 spaces. Also, what sized wire should I use from the RPC to the main panel? I was thinking 2 gauge copper with a 70amp breaker as it is a 25hp but i don't have the specs in front of me so I will have to double check.
Square D is the only brand I will use. QO type breakers. You will need breakers x 3 = spaces and spares for the future. I would get a 30 circut with a main breaker. Main depends on output of rpc. I have not done one in years since vfd's came out. What is output amps of rpc? And I would have starters with overload protection on each motor if you do not. Have you priced vfd's compared to rpc?
Square D is the only brand I will use. QO type breakers. You will need breakers x 3 = spaces and spares for the future. I would get a 30 circut with a main breaker. Main depends on output of rpc. I have not done one in years since vfd s came out. What is output amps of rpc? And I would have starters with overload protection on each motor if you do not. Have you priced vfd s compared to rpc?
VFD's would be very expensive. There is a guy in Canada that makes custom VFD's at good prices but it's still too high compared to the cost of a used RPC. I think he quoted me $800 for a VFD for my sander and $185 for the feed motor with $80 and $60 shipping and he said they have to be shipped separate. I would imagine my dust collector would be $800 + $80 as well. My table saw VFD was $500 + $60 and my shaper is $250 + $60 and feeder would be $185 + $60.
The RPC that I am buying is $500 so it would be much more economical. Planing on getting a 30 space Square D 3 phase panel which is $275 and each 30 amp 3 pole breaker is like $175 and the 20amp 3 pole breakers are $75 each. The wire is not going to be too bad as I have a buddy that gets 20% off at my local electricians supply house. I will be using conduited wire.
My 10HP wide belt sander and 10HP dust collector each list 25amps at 240v which is what they will be wired at, so would a 30amp breaker be ok or should I go with a larger breaker?
I have them on my table saw, and shaper. Would need to purchase new ones for the dust collector, and wide belt sander. I must admit I don't really see their purpose from a functional standpoint. If there is a 3 phase panel with independent breakers connected to each machine and then the panel to the RPC, wouldn't the factory on off switch be fine?
What type of switches? Are the original switches magnetic with overload protection? The overload heaters in each phase in the starter protect the motor. The overload heaters are sized closer to the actual amperage draw of the motor, protecting the motor, but also the wiring because the breaker is sized large enough not to trip on startup current.After being an industrial electrician for over 40 years, and electricity being dangerous, I only do things the safe way. Safety is not always cheap, but I am not getting hurt, and will not advise anyone to take any shortcuts. The vfd will replace a starter, so they are not as expensive as they look. Take out the panel fed by the rpc, and there is more savings.
What type of switches? Are the original switches magnetic with overload protection? The overload heaters in each phase in the starter protect the motor. The overload heaters are sized closer to the actual amperage draw of the motor, protecting the motor, but also the wiring because the breaker is sized large enough not to trip on startup current.After being an industrial electrician for over 40 years, and electricity being dangerous, I only do things the safe way. Safety is not always cheap, but I am not getting hurt, and will not advise anyone to take any shortcuts. The vfd will replace a starter, so they are not as expensive as they look. Take out the panel fed by the rpc, and there is more savings.
Any idea on what size breaker I should run for my wide belt sander and dust collector? They each list 25amps at 240v so I was thinking 30amp breakers and 8 gauge conduited wire. Would that be ok?
Also, what size and type of wire should I get for wiring the RPC to the main panel and then the RPC to the 3 phase subsequent panel that will feed the machines?
In many states you can only legally do your own work on your primary residence that you own. If you have insurance on this shop they can deny any claim if any electrical work is done without a permit and inspection if it's required by the local regulations. This varies widely across the country. I would encourage you to look into the legal requirements before doing any work to make sure you are not jeopardizing your insurance coverage.
In many states you can only legally do your own work on your primary residence that you own. If you have insurance on this shop they can deny any claim if any electrical work is done without a permit and inspection if it's required by the local regulations. This varies widely across the country. I would encourage you to look into the legal requirements before doing any work to make sure you are not jeopardizing your insurance coverage.
Goes with my default "electrical questions" answer of asking a Licensed electrician, and then verifying with your insurance agent. I also point out, that in most cases you have 3 phase at the road. Most power companies will do the install, and it can be pricey, then you will be on a secondary service with a monthly meter charge. BUT, big "but" your insurance will be good, at least on that electrical hook up.
Totally disagree with " three phase at the road". Rarely in a residential area. And yes, always get an experienced electrician. Many states have no license. That is why I only post information from a reliable source, like the NEC. And few power companies do the install. They may send a contractor they work with.
No inspector in my area as this is the very rural south. Plus this is my shop and I am not worried about the insurance. I am not a professional electrician but I am confident that my work won't cause any fires. My buddy that is a licensed electrician will be assisting. I am just trying to gain a better understanding of what all I will need and how to implement it.
Don't know the output of the RPC as I don't have it in front of me.
Here's some info I had saved when I did my Rpc install.
Size the single phase supply (cord wiring, contactor) upstream from the rpc according to the hp rating of simultaneous client motors. Use NEC table 430.250 to get the ampere value for each simultaneous load motor, based on its HP. Multiply the sum by 250%. Size conductors and contactors for this number. Example: simultaneous 7.5 and 5hp load motors, 230v, the entries are 15.2 and 22 amps. Sum 37.2, x2.5 =93 amps. Yow. But doesn't need to be a NEMA size 3 or 4 contactor. Just needs to be sized for 93+ inductive amps.
Good Luck
7.5 hp shows 22 amps, 10 awg wire, and45 amo breaker. But it MUST have overload protection. The large breaker is for start up inrush. All the info I have posted comes from a Square D motor data calculator.
7.5 hp shows 22 amps, 10 awg wire, and45 amo breaker. But it MUST have overload protection. The large breaker is for start up inrush. All the info I have posted comes from a Square D motor data calculator.
Can anyone explain to me what kind of magnetic starter with overload protection that I would need for each machine? I know that my 7.5hp table saw and my 5HP shaper already have these. Is this just essentially a 3 phase magnetic switch? Which ones would I need for my 10HP wide belt and my 10HP dust collector? Can you link me to one or suggest a brand and model?
I would use either Allen Bradley or Square D, whichever is easiest to get. Both are top of the line and commonly available. Yes, a three phase contactor ( magnetic switch ) but starters have overcurrent protection for the motor. I will post 10hp size a little later.
A size 1 starter will take up to a 7 1/2 HP. A size 2 will take up to 15 HP. So for the 10 HP you will need the size 2. Sizes are standard between all brands.
A size 1 starter will take up to a 7 1/2 HP. A size 2 will take up to 15 HP. So for the 10 HP you will need the size 2. Sizes are standard between all brands.
Man those things are expensive. $250-$300 each. Doubt that I am able to afford one on each machine. Might buy one for my sander than later on get one for my dust collector. My 5HP shaper and 7.5hp table saw already have one on each.
You can get them used and refurbished, I have only purchased 1 new. Many were tear outs from jobs, and just reconnected at home. Starters are almost indestructible.
You can get them used and refurbished, I have only purchased 1 new. Many were tear outs from jobs, and just reconnected at home. Starters are almost indestructible.
Thanks for all the help guys! Now my last problem that I need your help with is for the plugs and recepticals. Where can I find the appropriate 3 phase plugs and recepticals? Can someone link me an appropriate 3 phase plug for each of the following machines and the appropriate matching 3 phase outlet that would mate to each plug?
Would the NEMA L15-30p be the correct plug for a 3 phase machine that is 240v and 25amp? I believe that it is. Then I would just get a matching NEMA receptical?
When wiring 3 phase plugs and recepticals are there any certain ways the wires go? Or is it like a standard 220 single phase in that the wires can go anywhere?
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