Replies

1. 
   Ronaway | Aug 23, 2007 06:01am | #1

   Lee,

   The motor may draw more amps on start up so you will need the 30 amp breaker, otherwise you may experience some nuisance tripping on startup. #10 copper wire is usually used for a 30 amp circuit but given the distance you're running the circuit you may want to upgrade to #8 copper just to be on the safe side. The difference in cost will not amount to the cost of getting a motor rewound because of a voltage drop and then you will have to rerun the circuit anyway if that happens. You may want to double check my suggestions with an electrician (I call them electromagicians) just to make sure.

   Ron

   If you're too open minded your brains will fall out.
1. 
   mapleman | Aug 23, 2007 04:09pm | #4

   Ron, Bruce, Paul:

   As always, excellent advice guys! After posting, I checked my breaker panel and as luck would have it, I have a 30 amp breaker open with nothing on it. So, I just need the wire and I'm ready to go.

   Paul - thanks for the specific info on voltage drop as related to # of feet. I will definitely bookmark that info for future reference.

   Thanks again guys,

   Lee

2. 
   BruceT999 | Aug 23, 2007 06:02am | #2

   1. Breaker should have higher capacity [typically 25%] than nominal draw of the load so theoretically you could use a 25A breaker, but those are not commonly used. The most commonly used breaker after 20A is 30A.
   2. 30 amp circuit takes 10ga wire [unless very long runs, which you don't have]. 10ga wire at 220V 25A will drop voltage less than 2% in 90 feet, so your 45 feet will be no problem. At 30A load 2% loss comes at 75 feet.

   BruceT

   Edited 8/22/2007 11:13 pm ET by BruceT999

   
   

   ---

   Edited 8/22/2007 11:17 pm ET by BruceT999

1. 
   paulm | Aug 23, 2007 01:56pm | #3

   Hi Bruce,

   The Breaker is required to be sized at 125% of the load based on Article 210 of the NEC.  The plug that is provided with your planar should be configured with a NEMA 30 A plug cap that will connect to the 30 A receptacle that you will need to install.  A 10 AWG wire from the breaker to the receptacle will be required.

   The rationale for the 125% rule is to prevent heating of the conductors during the operation of the equipment.

   Enjoy the planar, I'm Jealous.

   Paul

3. 
   highfigh | Aug 23, 2007 04:50pm | #5

   If you have ever seen your lights flicker when the 'fridge or AC kicks in, it's because of the peak current drawn. This causes a voltage drop, as stated and long wire runs compound the problem. You never want to size a circuit at the max of the machine(s) on it.

   Are you wiring it 220V?

   "I cut this piece four times and it's still too short."
1. 
   mapleman | Aug 23, 2007 05:31pm | #6

   Highfigh,

   Are you wiring it 220V?

   Yes, as far as I know, 220V is the only option - the specs don't say 110/220.

   Thanks,

   Lee

1. 
   bones | Aug 23, 2007 10:30pm | #7

   To my knowledge, I don't think you can get a 5hp at 110?Government's view of the economy could be summed up in a few short phrases: If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.

1. 
   BruceT999 | Aug 25, 2007 08:21am | #8

   A 5HP 110V motor would draw 52 amps, requiring a 65A breaker under the 25% over-capacity rule and #6 wire. A 220V 5HP motor requires a 30A breaker and 10ga wire. That's why motors larger than 2HP are wired only for 220V.BruceT

1. 
   Drew1house | Aug 26, 2007 08:17pm | #9

   I know the rules however I have walls that are already finished and I have checked on this with the saw manufacturer and he suggested a slow blow 25 or even a 30 amp breaker on a 220 line would be OK on a less than 10 foot 12 guage run. I am still a little nervous. I know it does not meet real codes... What do you think?Drew

2. 
   BruceT999 | Aug 27, 2007 12:45am | #10

   How big is the amperage draw of that saw motor?12ga wire is rated for 20 amps continuous load under normal conditions. A slow-blow 25A breaker is not going to trip until it sees more than 25A of current [actually, it is reacting to heat generated internally from that much current flow] for longer than a certain amount of time; perhaps 15 seconds or so. You could, therefor, be overloading your 12ga wires by 25% without ever tripping the circuit breaker. Will that generate enough heat in 10 feet of wire to break down the insulation and/or start a fire? I don't know, but were it my house I wouldn't want to find out the hard way. How do you know it's only 10 feet of wire run from service panel to 220V outlet? Often wire runs go up, across and down from panel to wall outlet. Is that the only device on the circuit?If it is only 10 feet, it should be easy to pull a short run of 10ga in conduit either on the outside wall or shop wall. If you won't or can't re-wire, at the very least, before deliberately overloading a circuit in your wall, I would temporarily wire an equivalent length of 12-3 Romex to your 25A breaker, enclose it in insulation and connect it to your motor, then run for a while under load [maybe rip up some 2x4 IPE :)] and see how hot that cable is becoming.at 20 amps, 220V, 12ga Romex is good for 36 feet at 2% or less line loss.BruceT