The Electrical Code

210.20 Overcurrent Protection. This is saying that the breaker needs to comply with what the A through D in this article is saying. Now there are two words here continuous and noncontinuous which means a device that is looking to use that level of power, weather is be 10, 15, 20 amps it is going to use that amount. Then there are devices that use that amperage on and off. Like with breaks in between when the device is asking for the full amount of amperage and cycles off. Much like a boiler(when the thermostat is asking for heat the boiler begins to produce heat and uses what ever is needs to heat the space and then turns off when the thermostat is satisfied). We will go through his in an independent blog later. This article refers to another article that we have not covered, 240.5 which cover flexible cable. And they want the breaker to be 125%. Just look at the machines label. In the machines label there is a amp rating for the device and you need to multiply that amp rating X 1.25 and that is the size of the breaker. Now remember that the breaker and wire size needs to coincide. This is important because even if your device needs 15 amp to operate, you truly need 18.75 amp or 20 amp breaker because they don’t make a breaker that is rated for 18.75. And even if the world was perfect and that was offered then the wire needs to meet those guidelines. If you have any question or comments please let me know.

“Branch-circuit conductors and equipment shall be protected by overcurrent protective devices that have a rating or setting that complies with 210.20(A) through (D).

(A) Continuous and Noncontinuous Loads. Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load.

Exception: Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.

(B) Conductor Protection. Conductors shall be protected in accordance with 240.4. Flexible cords and fixture wires shall be protected in accordance with 240.5.

(C) Equipment. The rating or setting of the overcurrent protective device shall not exceed that specified in the applicable articles referenced in Table 240.3 for equipment.

(D) Outlet Devices. The rating or setting shall not exceed that specified in 210.21 for outlet devices.”