The Keyway Splice Box system is fitted with a rigid metal lid that allows easy removal once required. A wide range of case sizes are available to suit the rebar detail requirement. The cases are perforated on the larger face to provide an excellent bond to the first concrete pour and provide an efficient key for the subsequent pour. The Keyway Splice Box cases are manufactured from galvanized mild steel rolled to precise dimensions. They are custom fabricated to meet exact specifications and job design requirements. Table 314.Keyway Splice Boxes are available with either a single or double row of dowel bars, straight dowels, hooks, stirrups and lap splices. We can usually see the capacity of electrical boxes indicated inside them. That means we need to find an electrical box with at least 32.06 in³ of volume to meet our requirements. And since our largest conducting wire is 12 AWG, our tool calculated the total box fill volume required of 32.06 in³ out of that wire size's required volume of 2.25 in³. Our box fill calculator will immediately display that we need 14.25 volume allowances. And finally, we choose 12 AWG for the largest ground wire size selection.Then, we enter 5 for the number of grounding wires.Next, we enter 2 for the number of devices.On the other hand, we choose No for the question on support fittings.We're planning to use an electrical box with internal clamps, so we select Yes for the question of "Are you using a box with internal clamps?".Among the selection, we then choose the wire size of the largest conducting wire that we will feed into our electrical box.Since we're going to feed six 12 AWG and two 16 AWG conducting wires, we enter 8 wires into the calculator. First, we enter the number of conducting wires that we need to feed into our electrical box (no matter their sizes).We prefer to use electrical boxes with a set of internal clamps, so we need to consider that too. The electrical plan also indicates we need to install 2 convenience outlet devices onto this electrical box. Let's say that in our electrical plan, we need to feed 6 pieces of 12 AWG wires, 2 pieces of 16 AWG wires, together with 5 pieces of 12 AWG grounding wires into an electrical box. We don't need to count any short wires, such as a pigtail wire, where their entire length remains in the box. Note that we should count a wire twice if its length is longer than twice the minimum length required for free conductors (which is 12 inches / 30 cm, as specified in Article 300.14: "Length of Free Conductors at Outlets, Junctions, and Switch Points"). You can use our wire size calculator if you want to learn how certified electricians choose the right wire size for a particular application. Conductor fillĪccording to the 2020 NEC®, we should count one volume allowance for each conducting wire entering or passing through an electrical box regardless of their wire sizes. Now let us discuss how many volume allowances each of these components will have in an electrical box. These components that we'll consider in the box fill calculations are the following: Each component attached to or entering an electrical box has its equivalent volume allowance. That means if an electrical component has an equivalent of two volume allowances, that component occupies the same volume as two conducting wires entering the box. The NFPA® presents the use of "volume allowances" in determining the total box fill we would need for a utility box.Įach single volume allowance corresponds to one conducting or grounding wire entering the box. However, it's necessary to do so that we follow the electrical building code to avoid potential danger and fire hazards. Finding out how much volume of an electrical box you need to use is easy.
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