Let's break this down: Pancake Box Capacity

You're dealing with a pancake box that has a listed volume of 3.9 cubic inches. This is the total allowable space inside the box for wires, devices (like a switch or receptacle), and connectors.

Wire Fill Calculation (NEC Article 314.16)

The National Electrical Code (NEC) specifies how to calculate the box fill required by conductors. Here's the key:

14 AWG Conductor Volume

Each 14 AWG conductor is assigned a volume of

2.0 cubic inches. Grounding Conductors

All grounding conductors collectively count as one conductor based on the largest grounding conductor. Since you're using 14/2, the ground wire is also 14 AWG, so it counts as 2.0 cubic inches total.

Device Fill

If you're mounting a device (switch, receptacle, etc.) in the box, you have to add a volume equal to twice the volume of the largest conductor entering the box and attached to the device. With 14 AWG that is equal to 2.0 x 2 = 4.
0.

Your Calculation



One 14/2 cable

Contains TWO current-carrying conductors and ONE ground.

Volume Used = (2 conductors x 2.0 cu in/conductor) + (1 ground as 1 x 2.0 cu in) = 6.0 cu in The Problem

The total volume for one 14/2 cable alone is 6.0 cubic inches according to the NEC. Your box only has 3.9 cubic inches available. Therefore, based on the NEC, you cannot legally install one 14/2 cable into this pancake box.

The Spec Sheet Ambiguity

The specification sheet is poorly written. It is contradictory to state that it accommodates 14/2 when the box's cubic inch capacity clearly doesn't allow for it based on standard NEC wire fill calculations.

Conclusion

You cannot "hang your hat" on the fact that the spec sheet says "Accommodates 14/2." The phrase is misleading.

Here's why you can't use it


NEC Violation

Installing a 14/2 cable alone exceeds the box fill capacity, violating the NEC. This creates a potential fire hazard and could cause issues with inspections.2.

Spec Sheet is Flawed

The spec sheet is incorrect or, at best, extremely misleading. It should specify how many 14/2 cables can be accommodated (which, in this case, is zero).

What to Do



Use a Larger Box

The safest and most code-compliant solution is to use a deeper electrical box with sufficient cubic inch capacity.

Do not install 14-2

Installing a 14-2 cable into this pancake box will violate the NEC and can create fire hazards.

Contact the Manufacturer

Report the error on the spec sheet to the manufacturer. This will prevent future customers from making the same mistake.

Consult a Qualified Electrician

When in doubt, consult a licensed electrician. They can help you determine the correct box size and wiring methods for your specific situation.

Important Notes

The NEC is the final authority on electrical installations. Always err on the side of caution and safety when dealing with electricity. Overfilled electrical boxes are a common cause of electrical fires. When doing electrical work, always turn off the power at the breaker and verify that the circuit is de-energized before touching any wires.
Disclaimer: I am an AI Chatbot and not a licensed electrician. This information is for educational purposes only and should not be taken as professional advice. Flag for review