Re: hypothetical question
Originally posted by ephesus56ad: Now the service is 200amp and the tub is 50 amp. . . . Is the wiring going to be fine . . . because the load does not exceed what the wire is rated for?
I think you have the right basic concept. But let me phrase it a different way: At every component in the wiring system, the amount of current passing through that component has to be no more than the component?s rating. If the Service Panel is rated for 200 amps, then the total load in the house has to be less than 200 amps. If only 50 of those amps are heading in the direction of the hot tub, then the wire need only be rated for 50 amps.
But there are several possible twists and turns in the plot for this story. Hal mentioned one: You need to have a 50 amp breaker at the main panel. If the homeowner has a 50 amp breaker at the main panel to serve the sub-panel, that issue goes away. But here are a few more issues:
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- <font size="2" face="Verdana, Helvetica, sans-serif">A #6 wire is only good for 55 amps if it is made of copper, and not of aluminum.</font>
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- <font size="2" face="Verdana, Helvetica, sans-serif">Not all types of wire are approved for underground installation. So if the homeowner ran part of the cable underground, then it becomes important to know what type of wire he used.</font>
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- <font size="2" face="Verdana, Helvetica, sans-serif">If a load is likely to run more than 3 hours at a time, there are rules about counting it as a higher load, and therefore giving it a larger wire. This would not come into play, if the 50 amp value is the number given by the manufacturer (i.e., they would have already taken the extra factors into account).</font>
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- <font size="2" face="Verdana, Helvetica, sans-serif">A very real, and potentially very dangerous, situation might arise, if the hot tub needs both a 220 volt and a 110 volt supply. Any external metal parts of the hot tub (and the sub-panel itself, by the way) have to have a safety ground wire going all the way back to the main service panel. That wire cannot be the same one that is used to give you the 110 volt neutral (or ?cold leg?). So if the manufacturer says that you need 50 amps of power at both 220 volts and 110 volts, then you would need four wires. If the 6/3 has a safety ground wire (typically bare copper), then it cannot be connected to the neutral wire at the hot tub or at the sub-panel.</font>
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[ April 13, 2004, 03:14 PM: Message edited by: charlie b ]