I recently purchased an indoor infrared sauna that pulls 18.3 amps
I read that the max capacity for 14 gauge wiring is 17 amp on a 110 volt service
Can I safely use a 20 AMP breaker with 14 gauge wiring for an appliance pulling 18.3 amps?
Electrical – Using an 18.3 AMP appliance over 14 gauge wiring
electrical
Related Solutions
Wiring from garage panel to welder
NEC 630.11(A) may be of interest.
National Electric Code 2008
ARTICLE 630 Electric Welders
II. Arc Welders
630.11 Ampacity of Supply Conductors.
(A) Individual Welders. The ampacity of the supply conductors shall be not less than the I1eff value on the rating plate. Alternatively, if the I1eff is not given, the ampacity of the supply conductors shall not be less than the current value determined by multiplying the rated primary current in amperes given on the welder rating plate by the factor shown in Table 630.11(A) based on the duty cycle of the welder.
Also take a look at 630.12 Overcurrent Protection.
The Owners manual (PDF) seems to contain the answer.
Wiring from service panel to sub panel
If we look at 110.14(C) in 2008 NEC, it says:
National Electrical Code 2008
ARTICLE 110 Requirements for Electrical Installations
I. General
110.14 Electrical Connections.
(C) Temperature Limitations. The temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination, conductor, or device. Conductors with temperature ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment, correction, or both.
Which means we'll have to check the breakers temperature rating, and the subpanel terminals temperature rating. Then we'll have to look at table 310.16 (Table 310.15(B)(16) NEC 2011), so we can determine the wire size we should use.
In this example image you can see if we're using copper, we'll use 60°C. Once we look at the table, we'll see that for 50A @ 60°C we need 6 AWG copper wire. (50A @ 75°C = 8 AWG).
110.14(C)(1)(a) basically says that if the temperature is not listed, use 60°C for circuits less than 100A. 110.14(C)(1)(b) says if the temperature is not listed, use 75°C for circuits over 100A. However, in the real world 75°C is often used for both.
While the panel is rated 125 amp, you have a 100 amp service. You also have an electric dryer and water heater in addition to the usual lights and outlets. Adding a 66 amp load to all of this is definitely overloading the service.
If you went ahead and installed this welder, you won't burn down the house (at least not from electrical loads, from welding is another story) but you would get nuisance tripping. Every time you struck an arc, the lights would dim. The resulting voltage drop could damage electronic equipment such as computers and TVs, as well as anything else with electronics, which is virtually everything these days.
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Best Answer
No. No no no no no.
The sole purpose of the breaker is to protect the wiring from overheating. It's not just there to be a buzzkill. If you use a breaker that is too high for the wire you will lose that protection and there is a very real possibility of overheating and starting a fire.
An 18.3 amp device needs to be on a 20 amp circuit, meaning the receptacle, wiring, and breaker all need to be rated for 20 amps. (That would mean 12 gauge wire or bigger.) By the way, is your sauna really 120V? I thought most of them were 240V, which of course is a whole new thing.