1) OK, very good........Yes, I ask many questions at times, but they are necessary.
2) The code requires that the conductors are to be sized at 125% of the Full Load Current. This results in 14 amps x 1.25 = 17.5 amps. Code also requires that the breaker be sized at 250% of the FLA = 14 amps x 2.5 = 35 amps. Since a 35 amp double pole breaker is not common, code allows to use the next standard size breaker which is a 40 amp double pole, 240 volt breaker. Based on 40 amps, the branch circuit conductors will need to be sized as 8 AWG stranded copper or 6 AWG Stranded aluminum. You will require 2 consecutive spaces either on the left or right hand side of your main electrical panel to accommodate the 40 amp double pole breaker. The neutral conductor going to the parts washer lands on the main neutral bus bar. The ground wire at the panel lands on an equipment grounding bar and not the neutral bar. If your panel does not have an equipment grounding bar, you can purchase one at any of the home improvement stores for around $5.
3) The voltage drop calculation based on a 40 amp load, 240 volt single phase supply @ a 50 foot run = 1.3% voltage drop or a loss of 3 volts. National Electrical Code recommends a voltage drop not greater than 3%. Therefore, you are OK to use either 8 AWG stranded copper or 6 AWG stranded aluminum.
4) Since the parts washer will be hard-wired, you will need a 240 volt double pole non-fused safety disconnect switch. The 2 hot wires (red & black) from the breaker will land on the LINE side of the disconnect switch. The LOAD side of the disconnect switch gets wired to the 2 hots of the parts washer. The neutral and ground wires DO NOT get wired to the safety disconnect switch, only the 2 hots.
A 40 amp safety disconnect switch is not a common switch, therefore, you can use a 60 amp rated 240 volt safety disconnect switch. Refer to the link below. Home Depot carries these as well as Lowes or any electrical supply store. The switch shown on the link below is rated for in-door use only.
5) Since you have existing conductors from the old spa tub, just make sure they are the minimum size I mentioned above. if so, then you are good to go and can use the existing spa conductors.
6) If you will be installing conduit, let me know the size of the existing wires and I can provide you with the proper diameter of conduit to use.
Hope this helps.........If you have any additional questions, let me know and I'll be glad to answer them for you.
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The next time you have an electrical question, you can also request for me at:http://www.justanswer.com/home-improvement/expert-your-electrician