d088 Posted August 16, 2009 Report Share Posted August 16, 2009 Hello everyone, I have finally purchased a hot tub, which I was able to find used for a good deal. I'm preparing to run the electrical circuit and found in the manual that the spa has the ability to convert between 30 AMP or 50 AMP setup. Can anyone help me to understand the pros/cons of running it at 30 AMP vs. 50 AMPS? It is a Leisure Bay G-2 Genius Series spa. The reason for asking is that when I built the house, I pulled an extra 10/3 circuit to the attic for future expansion needs, but I would have to run a new circuit and cut out drywall for a 50 AMP circuit. If there aren't any real drawbacks, it would be nice to use the existing circuit and save a couple-hundred dollars. Thanks for any help you can give! Ben Quote Link to comment Share on other sites More sharing options...
Roger Posted August 16, 2009 Report Share Posted August 16, 2009 Hello everyone, I have finally purchased a hot tub, which I was able to find used for a good deal. I'm preparing to run the electrical circuit and found in the manual that the spa has the ability to convert between 30 AMP or 50 AMP setup. Can anyone help me to understand the pros/cons of running it at 30 AMP vs. 50 AMPS? It is a Leisure Bay G-2 Genius Series spa. The reason for asking is that when I built the house, I pulled an extra 10/3 circuit to the attic for future expansion needs, but I would have to run a new circuit and cut out drywall for a 50 AMP circuit. If there aren't any real drawbacks, it would be nice to use the existing circuit and save a couple-hundred dollars. Thanks for any help you can give! Ben If you feel you need to run the heater and the pump on high speed at the same time you will need a 50 amp circuit. Quote Link to comment Share on other sites More sharing options...
d088 Posted August 16, 2009 Author Report Share Posted August 16, 2009 Being new to hot tubs, does "running the pump on high speed" mean that the jets are on? So essentially, whenever the heater turns on the jets would stop? Quote Link to comment Share on other sites More sharing options...
bart6453 Posted August 16, 2009 Report Share Posted August 16, 2009 Being new to hot tubs, does "running the pump on high speed" mean that the jets are on? So essentially, whenever the heater turns on the jets would stop? Yes, when the jets are on, the heater will not work. Typically the pump overrides the heater...so if you have the pump going...no heat until you turn them off. Go for the 50amp set up. The additional cost is very minimal...less than 20% additional for sure....and if you go with a 30 amp circuit.....and get a different tub someday...you will most likely need to re-wire. Also...if you live in a cold climate and plan on spending any time in the tub in the winter...you are gonna want all the power you can get. Really the only difference other than the breakers is the gauge of the wire. Quote Link to comment Share on other sites More sharing options...
n1oty Posted August 16, 2009 Report Share Posted August 16, 2009 Hello everyone, I have finally purchased a hot tub, which I was able to find used for a good deal. I'm preparing to run the electrical circuit and found in the manual that the spa has the ability to convert between 30 AMP or 50 AMP setup. Can anyone help me to understand the pros/cons of running it at 30 AMP vs. 50 AMPS? It is a Leisure Bay G-2 Genius Series spa. The reason for asking is that when I built the house, I pulled an extra 10/3 circuit to the attic for future expansion needs, but I would have to run a new circuit and cut out drywall for a 50 AMP circuit. If there aren't any real drawbacks, it would be nice to use the existing circuit and save a couple-hundred dollars. Thanks for any help you can give! Ben Others have already advised you of the difference between the 30 and 50 amp circuits, and its effect on tub operation. I wanted to address something else in your post that may or may not be a problem. I noticed that you wanted to utilize a 10/3 circuit that is already in your attic. Much will depend on the existing wire type and the hottest temperature that your attic may experience. I know it is commonly believed that any 10 AWG copper wire can carry up to 30 amps. However, this is not always correct. Wire type, ambient temps and the number of conductors in the conduit can all conspire to drop the maximum ampacity well below 30 amps. For example, the maximum ampacity of 10 AWG Romex (a 60 C conductor) is 30 amps. However, if your attic temps reach 105 degrees F during the summer and the Romex is subjected to this heat, the maximum ampacity of this wiring drops to 21.3 amps. If your attic gets hotter than this, then the de-rating will be much more severe. My point is, unless you live in an exceptionally cool climate where the attic never exceeds 70 degrees F, you may have problems with using the 10 AWG for a 30 amp circuit. I suspect that, at most, you could use it for a 15 or 20 amp circuit. I quickly checked the appropriate table in Article 310 of the NEC and found that, at a minimum, you would have to run a 90 C rated wire through the attic, assuming the hottest attic temperature between 105 to 113 F. A 10 AWG 90 C wire (such as THWN-2) at this ambient temperature has a de-rated ampacity of 34.8 amps. As a matter of fact, the ampacity of 90 C wire remains above 30 amps all the way up to 131 degrees F. I checked your profile and it does not state what part of the country you live in. I don't know, maybe you live in northern Alaska and this won't effect you. However, I realize that a northern Alaska scenario is not likely and that the odds are that you live in a warmer area. If so, this info may keep you from burning your house down. John Quote Link to comment Share on other sites More sharing options...
d088 Posted August 17, 2009 Author Report Share Posted August 17, 2009 John, Thank you for the information. I will always welcome additional feedback when it comes to safety! I rewired my house completely after Hurricane Katrina and exclusively used 90C rated wiring for just this reason. However, I was under the impression that the 60C and 90C wiring was not to be derated until temps reached 140 degrees and 190 degrees Fahrenheit respectively. By the way, I am in the New Orleans area. I appreciate your concern and for taking the time to share your thoughts. I ended up running a new 50A circuit today because my wife, "can't use the hot tub if I have to choose between jets and heat!" Add another $300 to the bill... Ben Quote Link to comment Share on other sites More sharing options...
n1oty Posted August 17, 2009 Report Share Posted August 17, 2009 John, Thank you for the information. I will always welcome additional feedback when it comes to safety! I rewired my house completely after Hurricane Katrina and exclusively used 90C rated wiring for just this reason. However, I was under the impression that the 60C and 90C wiring was not to be derated until temps reached 140 degrees and 190 degrees Fahrenheit respectively. By the way, I am in the New Orleans area. I appreciate your concern and for taking the time to share your thoughts. I ended up running a new 50A circuit today because my wife, "can't use the hot tub if I have to choose between jets and heat!" Add another $300 to the bill... Ben Congratulations on the foresight to use the higher rated wire. Too bad you can't use it now since you are going with 50 amp service to the tub. It is always possible that your jurisdiction has relaxed de-rating percentages for temperature, but I really doubt it. Most jurisdictions, if they modify a section of the NEC, usually increase the level of protection. The NEC is generally perceived as a set of minimum standards. I carefully re-read the percentages from the Table in the NEC with the temperature de-rating factors and stand by my earlier statement. However, as in all cases when discussing electric code, you would be prudent to check with your AHJ for any changes required in your jurisdiction. John Quote Link to comment Share on other sites More sharing options...
quantumchromodynamics Posted August 17, 2009 Report Share Posted August 17, 2009 You should calculate the voltage drop for the circuit under load. The voltage drop should be less than 3 %. 1) "Adverse" conditions (warm climate). 2) 100 foot circuit length. 3) 6 AWG copper wire. 4) 240-volt. 5) 1 phase. 6) Voltage drop = 5.8 volts (2.4%) http://www.southwire.com/voltagedropcalculator.jsp http://www.cablecalculator.com/ http://www.csgnetwork.com/voltagedropcalc.html http://www.csgnetwork.com/wiresizecalc.html http://www.gorhamschaffler.com/wire_size_calculator.html Quote Link to comment Share on other sites More sharing options...
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