Replies

1. 
   DickL | Mar 05, 2007 11:02pm | #1

   >Does anyone currently run 10 gauge with a 30 Amp machine and if so.. any problems or fore-seen ones that could create a hazard in the making?

   I have a 20" Bridgewood with a 5hp Baldor motor. It's on a dedicated 10 gauge circuit with a 30 amp breaker. I think the amps on the motor is less than 30. Runs just fine.

1. 
   SARGEgrinder47 | Mar 06, 2007 08:53am | #7

   Thanks Dick.. please see post #7

   Sarge.. jt

2. 
   Stuart | Mar 06, 2007 12:18am | #2

   If the wire is connected to a 30 amp circuit breaker in your panelboard, it needs to be 10 gauge.  If you go to a 40 or 50 amp circuit breaker, the wire size will have to be increased to 8 gauge.

   As far as what size circuit is needed for a 5hp motor (I assume we're talking 240volts single phase here) my guess is you'll need about a 40 amp circuit, but the best thing to do is figure out what planer you want first and then change the circuit as required to meet the manufacturer's standards.

1. 
   SARGEgrinder47 | Mar 06, 2007 08:54am | #8

   Thanks Stuart.. please see post #7....

   Sarge.. jt

3. 
   CarvinChris | Mar 06, 2007 12:57am | #3

   Hey Sarge, I'm an electrician by trade, #10 wire is recommended for 30amps, for 40amps you will need #8 wire. I am assuming that your 5hp motor is wired for 240volts and a 30amp circuit will do just fine. Perhaps I should take a moment to note something about breakers: they are only rated to work at 80% of their value, i.e. a 20 amp breaker will trip at 16amps,a 15amp breaker trips at 13amps. Your 30amp breaker will trip at 22amps. I've hooked up many a 5hp motor on 30amp breakers with no tripping problems. That said, your planer may draw close or better than 22amps, which may cause your breaker to trip during use. If this happens you could protect your #10 wire with a 35amp breaker which will trip at 28amps. 10 gauge wire is rated to carry 30amps, so you won't have any problems. Hope this helps.

   
   

   ---

   Edited 3/5/2007 5:46 pm ET by carvinchris

1. 
   RickChristopherson | Mar 06, 2007 03:40am | #4

   Carvinchris,
   The information you provided on circuit breakers is not correct. A 20-amp breaker, for example, will trip at a nominal 20 amps, with a margin of error to either side. It may be a little above or a little below, but the nominal trip point is 20 amps.I believe you are confusing this with the numbers for derating a circuit. When you design a circuit, you need to plan for 80% capacity, but the circuit is available for use at 100% capacity. Also note that by definition a cord-and-plug circuit does not know what load will be plugged in, so derating does not apply. When you preface your answers with credentials, you need to be extra careful about the information you provide.
   =============
   To the original poster,
   Your 30-amp circuit with 10 ga wire will operate your 5 hp planer just fine. The high inrush current is short duration, and therefore, does not build up heat in the circuit of sufficient levels. A typical 5 hp motor will draw 24 amps at full rated load, but it is rare that the motor will reach full rated load, and even then, for only short periods.

1. 
   SARGEgrinder47 | Mar 06, 2007 08:56am | #10

   Thanks Rick... please see post #7...

   Sarge.. jt

2. 
   SARGEgrinder47 | Mar 06, 2007 08:56am | #9

   Thank you carvin.. or Chris... please see post #7.....

   Sarge.. jt

4. 
   eweber2 | Mar 06, 2007 04:20am | #5

   I am running a 5HP table saw and a 5HP planer both wired on their respective 30 Amp breakers and never tripped a breaker a startup.

   10 gauge is what you need for running 30 amp.

   Check the amperage on your name plate, usually 5HP motor have an amperage below 26A which should be fine. Some older motor with less efficiency might draw more amps. In that case you should use a 40 amp breaker with 8 gauge wire.

1. 
   SARGEgrinder47 | Mar 06, 2007 08:51am | #6

   First.. my thanks to all that answered. As stated I currently have a two 20 A circuits. One down each side of the shop that has #12 wire with 20 A breakers and outlets. I have a single 240 v on the ceiling from the box down the center of the shop which I use for 220v and all my 3 HP machines which all rate at under 20 amps. The 220 v has a 30 Amp breaker and is currently run with #10 gauge.

   I would not given a thought to the need for something larger as most of those I know that run 5 HP do it on a 30 Amp circuit with #10 gauge. But... something popped up in my search for "the Planer" that caught me off-guard and resulted in this thread. Most 5 HP I have en-countered are rated at under 30 Amps.

   While reviewing an ad for the Shopfox 20" I encountered this in the specs. I don't know if they mean it draws 30 Amps consistently or if that is just the circuit set-up. It is very un-clear to me and sets wheels spinning as to an up-grade from 30 Amp with the current and correct #10 gauge to a 40 Amp and #8 gauge to cover start up surges? The ad is as follows:

   Go figure what they imply by 5 HP 30 Amp? Any thoughts on their statement would be welcome. If iin doubt at that point, I will call each distributor and ask them to go the respective machine physically and get the Amp rating off the motor case. Any better suggestions with this in mind... I'm all ears!

   Again thanks Dick.. Stuart.. Carvin.. Rick.. and eweber

   Sarge.. jt

   W1747 - SHOP FOX¯ 20" Planer With Switch Arm

   You can't ask for more great features in a 20" planer than these: Four knives, solid cast iron extension tables, side-mounted magnetic switch, full width board return rollers, adjustable bed rollers and a powerful 5 HP motor. All of these features add up to an incredible planer performance and a finish that's second to none.

   Motor: 5 HP, 220V, single-phase, 30 Amp, TEFC

1. 
   RickChristopherson | Mar 06, 2007 10:26am | #12

   Actually Sarge, the answer is quite simple. You already have the 30 amp circuit in place. Connect the planer to the circuit when you get the planer. If it trips the circuit (it won't) then upgrade the circuit. If it doesn't trip the breaker, then all is well. The circuit breaker is there to protect the wire and to prevent you from overloading the circuit. It knows better than we do, and it won't let you operate a tool larger than the circuit can handle. The heating effects of inrush current on the circuit are negligable unless the motor fails to spool up in a normal time, or if the motor is constantly restarted every couple of seconds. But even this doesn't matter because the circuit breaker also accounts for this too. Regarding the second half of your question, an idling induction motor will draw approximately 1/2 of its nameplate rating. The 5 hp motor will draw about 12 to 15 amps at idle, depending on the mechanical load of the drive and cutter drivetrain.

1. 
   SARGEgrinder47 | Mar 07, 2007 02:14am | #14

   Evening Rick...

   Thanks for the in-put. I called Wilke today and got Curt. Curt knows his machines and says the the rating on the Yorkcraft  5 HP is around 21-24 amps going on memory. He also stated the 30 amp breaker was the way that most of his 5 HP customers are set up.

   As you stated and it just makes common sense, if 30 amps is not enough to handle it the breaker will "send up a red flag" by it's continuance to trip. I am confident at this point that it will not having been assured the machine is rated below the deceiving spec in both Shopfox's and Grizzly's spec sheets.

   Regards...

   Sarge.. jt

2. 
   SARGEgrinder47 | Mar 06, 2007 08:57am | #11

   Thanks eweber... Please see post #7...

   Sarge.. jt

5. 
   TKanzler | Mar 06, 2007 09:17pm | #13

   "But... with a surge that could as high as 40 Amps, . . ."

   Locked-rotor, or starting current for a 5 hp 240V motor is more like 125A.  But it's not normally a problem for a 30A breaker, as what you're likely to have in your panel is a time-delay (or inverse-time) type breaker.  Small overloads can take potentially hours to trip the breaker, and the higher the current, the shorter the time to trip, to the point where a magnetic mechanism trips the breaker almost instantly (like 1/2 cycle), at something like 7 times the rated current or more, depending on the manufacturer and ampacity.  The upshoot is that you don't need to worry about startup currents through the wiring and breaker, as they both can handle it just fine.

   Be seeing you...

1. 
   SARGEgrinder47 | Mar 07, 2007 02:44am | #15

   Evening TK...

   Thanks for "weighting in". As I just posted to Rick, I am confident that the 30 A is the ticket to ride as I called the distributors and confirmed that their 5 HP's draw in the 21-24 range. 

   But when checking my circuit today, I realized that I had put a 20 amp breaker.. a 20 amp receptacle with 20 A twist locks on the current machines as they have 12 A and 16 A draws which have smaller gauge wire in thier self contained plug-in cords from the machine itself.

   The good news is I ran #10 wire in case of a future purchase of 5 HP. So.. I will change the breaker in the main box to 30 A and the receptacle to 30 A twist lock to handle the planer. Then I will run a short piece of #10 wire off the open side of the first 30 A receptacle to a small sub-box below the 1st receptacle. I drop a 20 A breaker in that box and come out to receptacle #2 mounted 12 inches below that sub-box on the same up-right metal ceiling pole. I use #12 wire here with a 20 A receptacle and 20 A twist lock plugs .

   That will give me 30 amps protection for the 5 HP planer receptacle and reduce the the secondary receptacle to 20 amp protection for the smaller draw 12 A and 16 A which have thinner gauge wire in their stock plug-n cords.

   And of course.... only one machine would be run at a time on that dedicated circuit! I just haven't figured a way to operate more than one large machine at a time............... yet!  :>)

   Regards..

   Sarge.. jt

    

    

1. 
   RickChristopherson | Mar 07, 2007 09:32am | #16

   Sarge, It is not necessary to rewire the power cords on the tools, nor is it necessary to drop down to a different circuit breaker size from the existing 30 amp breaker of the main circuit. The only reason for doing this is if you wanted to reuse the 20 amp outlets that you already have, when you upsize the breaker back to the circuits rated ampacity of 30 amps. I think you may find that the cost of adding the breakout boxes will be higher than buying new plugs.The tool manufacturer sized the power cord on the tool according to the expected current draw from the tool. In accordance with article 240-4, exception #1, your tool cord can be as small as 16 gauge and still be connected to a 30 amp circuit.The logic behind this part of the NEC is that the cord is sized according to the specific tool, so the current flowing through the cord will not exceed the ampacity of the cord under normal circumstances. Furthermore, the cord is open-air, so it will cool itself better if overloaded, and also because it is visible if a problem were to arrise.

1. 
   SARGEgrinder47 | Mar 07, 2007 07:13pm | #18

   Morning Rick..

   Thanks again  for the reply. So.. you say instead of coming off that 30 receptacle with an inter-mitten two pole 20 A I can just change to 30 amp twist lock plugs on the smaller draw machines without concern? I know this what you said.. but again I am no electrical guru for sure and want be absolutely sure I read you "loud and clear"! ha.. ha...

   If that is the case... I will certainly do that as it will cost about $50 to drop the extra 20 amp breaker.. box.. and receptacle below the 30 A. This is a case where I think most of non-electrical types get confused and over-think with un-certainty over what is safe and what is not!

   Regards...

   Sarge.. jt

    

1. 
   RickChristopherson | Mar 07, 2007 08:40pm | #19

   Yes, Sarge, you read that correctly.

2. 
   SARGEgrinder47 | Mar 07, 2007 09:03pm | #20

   Thanks Rich... done deal!

   Sarge.. jt

2. 
   brownman | Mar 07, 2007 10:47am | #17

   Thanks for that reply! I'm also now better educated. I always wondered why my 5hp wide belt sander didn't trip off as the Amp meter always spikes to the max on initial start up. Thanks for sharing!
   Danny