In the electrical world there is always more than one term to describe equipment as well as circuitry. This can be a challenge for young apprentices trying to learn. There are branch-circuits, Multiwire Branch-circuits, Class 1,2 &3 circuits, Individual circuits, Dedicated circuits, Luminaries, Lights, and a lot more. In this article we will be discussing “dedicated circuits” or to be technical Individual circuits.
In the National Electrical code book an individual branch- circuit is a circuit that is dedicated to one load or piece of equipment. Out in the electrical field or in within electricians conversations, the term “Dedicated circuit” is used to say the same thing.
There are some things electricians should know about dedicated circuits. There really isn’t anything wrong with them but there are some allowances if you will for a dedicated circuit. Let me give you a scenario.
I got a call from an electrician, he had a question. He wanted to know why a sona that he was asked to wire up by a client had a 20 amp rated plug attached to it by the manufacturer. He said the saona’s nameplate said that it pulled 19.8 amps. He then asked if he had to size the wire and breaker at 125% because it was a “continuous load”. According to article 100 of the National Electrical code the definition of a “Continuous Load” is a load that is expected to operate for 3 or more hours. My question to him was,” how is this a continuous load?” He said that he thought all heating elements were continuous loads. I’m not sure where he learned that but it’s definitely not true. The definition in the code book doesn’t mention such a thing, it just mentions the 3 or more hours. Now the funny thing is, a sauna usually has a timer that shuts it down after 60 min. So we know that is not a continuous load. This electrician was confused. Let’s take a look at some of the code I referred him to so that he could understand.
There are a couple of NEC codes that pertain to dedicated circuits. Section 210.22 which is entitled “Permissible loads Individual” says that an individual branch circuit can be rated to supply any circuit in which it is rated, but can’t exceed the branch-circuit rating. This code section is talking about how much we can load up a circuit amperage wise.
Section 210.21 (Outlet Devices), this code section has a couple of sub-sections, they are, A) Lampholders & B) Receptacles. We will be discussing 210.21(B)(1) here.
In the call that I had from my good electrician friend, He wanted to take off the cord end provided by the sauna manufacturer. This would be a code violation according to 110.3 (B). This code section tells us that we need to wire equipment according to the manufactures listed and labeled instructions. If a manufacturer puts a cord on a piece of equipment , it’s obviously intended to be used.
We need to go back to 210.21(B)(1). This code section says that if we are using a receptacle device for a dedicated circuit, then that receptacle can only have one device on it. Receptacles that are most commonly used are the ones with 2 devices. Well 120 volt 15-20amp receptacles that is. Receptacles like the ones used for your dryer or oven that have 1 device can also be found for 15 and 20 amps. So if you have a dedicated circuit that is a cord and plug connection you have to use a “plug” (receptacle) that is rated for the same rating as the circuit. This sounds obvious but there are certain types of circuits that we are allowed to have a receptacle device that is rated less than the circuit. For an example. Look in the kitchen in your house. More than likely your receptacles are 15 amp rated, but even more than likely they will be on a 20 amp circuit.
There will be other articles about those types of circuits. In closing, a lot of people assume that we can only load a circuit up to 80% of a breaker. There are some codes for certain types of circuits that say that. But for dedicated circuits we can wire them up to 100% on a non-continuous and 125% of a continuous load (210.19 & 21.20).
So don’t be that electrician that just puts everything at 80%. My friendly electrician called me. Saved himself time from running to the part store as well as money in parts. He just needed a 20 amp receptacle that had 1 device. Keep studying and let that knowledge make you money.