Remember that the NEC code book states that following the minimum code requirements does not necessarily provide an efficient installation. and even some materials made right here, I have had issues in the past with sub-standard quality. With so much material being manufactured outside of the U.S. I will NEVER over-current a wire, as I have seen way too many breakers fail to do their job, resulting in major repairs. As far as oversizing the breaker, good luck getting me to go for that! My six grandchildren were sleeping upstairs when the split hvac unit outside compressor locked-up and completely melted the bus bars in the main breaker panel with the breakers never tripping.
#3 POLE 15 AMP BREAKER SERIES#
Unless you can show the inspector in the NEC codebook a valid exception, and gently convince said inspector to give you a variance, you will likely be in for a serious uphill battle. 15 Amp, 3-Pole Series C NEMA F-Frame Molded Case Circuit Breaker, Type EHD, Cable In/Cable Out, 14 kAIC, 480 VAC, 250 VDC, Fixed Thermal-Magnetic Trip. It is the wire insulation that breaks-down, not the current-carrying capacity. Different insulation material ratings just add more confusion, as this will vary your wires maximum ampacity under code. Arguing will very likely cause no end of future grief for the homeowner. One can argue semantics all you want, but the inspector is going to want #14 wire matched up to a 15 amp breaker, #12 wire to a 20 amp, #10 to a 30 amp, etc. Most local inspectors only care about what they see at first impression. In addition, this subject is discussed in further detail by Mike Holt in the following video: See Figure 440-5 and 440-6 in for a clear explanation.
It's kind of complicated, but it's all in the NEC, Art.440, Section III.īelow is an excellent overview on Art440 by one of the most respected names in the electrical business, Mike Holt. This is not a hard and fast rule, but it is typical and works for most installations.
Things are NOT always as simple as a chart at the home center or a simple electrical book.įor an air con unit you would typically size the conductors to the minimum circuit ampacity (MCA), and size the breaker to the maximum overcurrent protection (MOP). I would not expect the average home inspector to know this.Ī/C units, welders and electric motors have different rules than the "standard" breaker sizing rules. These types of quality, industry exclusive products keep the Square D brand ahead of the competition and are builders and electrical contractors first choice in electrical protection.It is perfectly within reason to have #12 wire protected by a 30A breaker when the circuit feeds an A/C unit. They come in many different sizes and can meet the needs of virtually every function in your home or business. QO circuit breakers have features no other manufacturer can offer. This enables you to easily distinguish which breaker has tripped in a load center that may contain up to 42 different circuit breakers. When a QO Visi-Trip circuit breaker trips, the handle snaps to a midpoint position between "Off" and "On" and a highly visible, red indicator easily identifies the tripped breaker. All QO circuit breakers are equipped with the exclusive Visi-Trip indicator. The ANSI-certified and UL-listed unit is rated for 240 VAC, 10,000 AIR and bolt-on installation. The Square D by Schneider Electric QO 15 Amp 3-Pole Bolt-On Circuit Breaker is intended for overload and short-circuits protection of your electrical system.
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