Mike Dolt Enterprises
Mike Dolt Enterprises
User: davek99, Location: Pittsburgh, PA
Asked on: Monday, May 12, 2025 at 1:12 pm EDT
Answered on: Tuesday, May 13, 2025 at 8:24 pm EDT
Question: I'm wondering if there are any restrictions in the NEC that would dictate the current capacity of a switch (15A vs 20A) if there are other switches 'down stream' of that switch. My reading of 404.14(A) just states that switches shall be listed/used within their ratings and therefore 15A rated should be fine. But does having that switch feed other switches change anything?Here is the scenario:-Hotel guestrooms where multiple things in the room are all feed from the same breaker (lighting, receptacles, bathroom fan, etc - all one 20A breaker for the room).-There is a 'master' switch by the door that would turn on/off all lights in the room. Only hardwired lights (no receptacles). This is the device I'm concerned with.-Downstream of this master switch would be multiple switches to control the individual lights in the room (the entry downlight has a switch, the bedside reading light has a switch, etc).If our total connected load is only about 6A, is there anything about having multiple switches down stream of master switch that would require that the 'master switch' be rated for anything over 15A?
You're on the right track. Based on the information you've provided, a 15A switch should be acceptable in the master switch position. Here's a breakdown of why, based on the NEC, and some key considerations: NEC 404.14(A)
As you pointed out, this section is the most relevant. It generally states that switches must be used within their ratings and be suitable for the application. Since your load is only 6A, well below the 15A rating of the switch, and it's controlling lighting (a general-use application for a switch), you are generally compliant.
NEC 210.21(B)(1)
This section addresses the rating of receptacles and cord connections. It does not directly apply to lighting circuits that are permanently wired. The section states:
210.21(B)(1) Single Receptacle. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit. This only applies if the devices down stream were receptacles and NOT switches. Overcurrent Protection
The 20A breaker protects the entire circuit. The 15A switch is allowed because it's rated to handle more than the continuous load (6A). The breaker is intended to protect the wiring from overcurrent, not necessarily each individual device.
Switch Endurance and Listing
While the continuous load is low, consider the endurance rating of the switch. Is it rated for the number of on/off cycles expected in a hotel room? A better-quality switch, even at 15A, might last longer in a high-use environment than a cheaper 20A switch.
Important Considerations and Caveats
Continuous Load
If your 6A load is considered continuous (defined in the NEC as operating at its maximum current for 3 hours or more), then you need to factor in the 80% rule for overcurrent devices (210.19(A)(1)). This means your maximum continuous load on the 20A breaker should not exceed 16A (20A x 0.80). Since your load is 6A, this is not a problem. However, if you add more to the circuit in the future, keep this in mind.
Local Amendments
Always check for any local amendments or additions to the NEC. Jurisdictions can sometimes have more stringent requirements.
Manufacturer's Instructions
Always follow the manufacturer's instructions for the switches and any other electrical equipment being installed.
Future Proofing
While a 15A switch is compliant now, consider if the lighting load is likely to increase in the future. While not required, installing a 20A switch might be a more robust solution for future expansion or changes to the lighting design.
In summary, based on your description and understanding of the NEC, a 15A rated 'master' switch is acceptable. However, you should always verify the load is not considered a 'continuous load' and consider if it would be beneficial to use a 20A switch to 'future proof' the design. Flag for review