Setting Up Electrical in My Shop

Scra99tch

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I will get a electrician to help me out with this but wanted to run it by you guys before hand

Right now I have 3 * 3 Phase machines being powered, not all at once but with a 5HP RPC.

I have the RPC connected to a 50AMP breaker with #12 wire to the panel. From the RPC I have a pigtail female 4 prong socket that I will have connected to an 10-4 extension cord to plug into each other machine. Eventually putting a series of 2 or so sockets on the wall and plugging the machines into this too have two running at a time (no more than 4HP with combined motors).

I would like to add a fused safety switch lever to shutoff the machines and to somehow shut down the RPC as well.

How would I wire a fused safety switch to the panel?
 
If you just want a disconnect upstream of the RPC, then it would sit between your 50A breaker in the breaker box and the RPC. I'd opt for rigid conduit to where the RPC sits and install the switch there.

You could alternatively install 3 disconnect switches after the RPC to lock out each machine individually. More cost but more flexibility.
 
Number 12 wire is 20 amp wire.

Swap out the 50 amp breaker for 20 NOW.

20 amps not enough for 5 hp...

Pull correct wire for the 50 amp breaker and you should be good there...

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
Yikes! I didn't even think about the ampacity when I answered quickly above. You'd be looking at running #6 AWG wire from the 50A breaker OR installing a 20A breaker as @tq60 mentioned.

Failure to do so could cause that wire to ignite and start a fire. Please be safe and have your wiring verified by a qualified electrician.
 
Are you servicing the shop, and the residence on the same switch panel, or do you have 200 amp service, and split panels?
 
Number 12 wire is 20 amp wire.
Swap out the 50 amp breaker for 20 NOW.
20 amps not enough for 5 hp...
Pull correct wire for the 50 amp breaker and you should be good there...

Number 12 wire is several sizes too small~~~ That's a given. A further consideration is converting from single to three phase. That would load up the line even further. A factor of 1.73 (or better) for the breaker and wire size will give you a little wiggle room. Remember, the NEC is not a standard, it is the minimum acceptable to a situation.

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Okay thanks for setting me straight.
How’s a 40 Amp breaker on 8 gauge wire sound. Gives me a little more wiggle room. I have it in 1/2in flexible conduit. The 8-2 wire is romex and I have that through the conduit. I would of taken the wire out of the Romex but the ground was unshielded.

I then have 40 amp male female twist lock 10-4 extension cord to the machine I will run.
 
You really should have 8 all the way to the motor. Why not just run a 30 amp breaker with the wire you have? It would be more than sufficient for your needs, and you wouldn't be under size on your wire. Mike
 
That upgrade gets you out of the fire hazard range. Actual "Ampacity" has never come into the discussion. To specify that, we would need to know the actual full load amps of both the rotary converter and the machine. On the motor name plate is a number following an FLA stamp. It will be somewhere on the name plate, not necessarily in any one spot. That number is the full load amp rating for each segment. The wire size will vary depending on that number.

For the first stage, to the rotary converter, take the name plate rating, FLA, multiply by 1.73, and that determines the wire size to the converter for a single phase input. The output of the converter should have a small breaker box, with three breakers. One for each of the machines hooked up to it. If a single plug connection is to be used for the machines, use a single breaker rated for the machine with the highest amps.

5 horsepower is not that big, my compressor has a 5 horse single phase motor. But, it is large for a residential distribution system. Add in the 1.73 single to three phase correction and it's a heluva starting current. A circuit breaker has time rated compensation to allow for motor starting. Be sure any fuses used have the same. You should figure on 3 times for the first few seconds. Starting unloaded may lower that a little, but~~~

It should be noted that "portable cable", plug connected line cords, will often have a higher amp rating than wire in a conduit. Not always, but "type RU" is one type of insulation that will. Romex and THHN will not, they must use the "wire in conduit" rating. There will be an insulation type usually stamped on the jacket of the cable. It won't make much sense, but your electrician will know what it indicatea.

Now, to your original question: a "fused disconnect". If breakers are used, a "fused" switch is not needed. It can be any switch capable of handling the current involved. A "toggle" switch will suffice, like a fused disconnect but without fuses. Do not use a "light" switch, or any residential style switch. Use an industrial style switch. It ain't pretty, but does the job, well. Mount the switch where it will be easy to switch off, unobstructed, and where it can be reached on the way out. Think of the machine "blowing up" and mount it near the path to the door you would be running toward.

As a parting shot, I will point you to http://www.hudsontelcom.com/uploads/ShopElex.pdf, an overview of what you will be dealing with. The ending of the article has been deleted, dealing specifically with your situation. But it will give some indication of the situation leading up to your install. Reading it will not make you an electrician but should give you enough insight to be able to talk to your electrician.

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