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What Does SWD Mean on a Circuit Breaker? SWD vs HID

Writen by Edwin Jones

Fact checked by Andrew Wright

what does swd mean on a circuit breaker

Have you been shopping around in your local hardware store or online and come across circuit breakers marked with “SWD”? I assume, “What does SWD mean on a circuit breaker?” was one of the first questions that came to mind?

It means Switching Duty or Switch Duty. It’s not really technical, as it implies the breaker can take the place of a switch. You can use this breaker to turn fluorescent lighting units on or off.

What Are SWD Circuit Breakers?

The SWD meaning I stated above is rather simplistic. It’s worth knowing how these types of breakers work and what specific applications they are designed and used for.

While I’m not sure when SWD-marked breakers were rolled out, older electricians who received their studies in the 1970s and 1980s can vouch that they already encountered them and the term in older versions of the Code.

As I’ve said above, they’re usually installed as a switch in a circuit, usually for lighting. With a switch circuit breaker, you’ll be able to manually control your luminaires (i.e. the current’s flow in the lighting circuit), while enjoying protection from overloads and other applicable electrical issues, much like any standard breaker.

15-swd-breaker

No less than the NEC and ANSI agree with the viability and usefulness of this type of circuit breaker. However, the need for frequent control and long-term reliability limits their applications to certain setups only, namely controlling fluorescent lighting, not incandescent lighting.

After all, you’re technically manually breaking the circuit every time. Just imagine how often the average household turns lights on and off a day to get the whole picture.

The NEC dedicates a section (240.83(D)) for the use of these breakers. It states that breakers that switch fluorescent lighting luminaires with 120V or 277V must be labeled as either HID or SWD. 

Naturally, you’re probably also curious about what “HID” means. Let’s compare the two, then.

SWD Breakers VS HID Breakers

20-swd-breaker

SWD breakers and HID breakers serve the same function said above. HID stands for high-intensity discharge. The following key facts differentiate the two:

  • SWD breakers may be used to switch fluorescent lighting circuits up to 20 amps. The same can be said for HID breakers, which can be rated up to a higher 50 amps. This is why you’re likely to stumble upon a single-pole 15 SWD breaker or a 20 SWD breaker when shopping for these switch breakers.
  • HID breakers can also switch high-intensity discharge luminaires – a specific capability that isn’t present in SWD breakers. Besides having higher ampacities, they’re also available in multiple-pole varieties.

Incidentally, don’t expect either one to function as the main circuit breaker, as their specialized switching feature doesn’t fit the purpose of that kind of breaker. Repetitive use may increase the risk of encountering dangerous situations like the main handle breaking, which may cause electric shocks. Such issues need to be seen by an electrician ASAP.

Who Makes SWD Circuit Breakers?

Eaton is one of the top manufacturers of SWD breakers, with dedicated literature regarding their uses. I can name other companies on top of my head, and you can check for yourself on sites like Amazon and eBay, including Federal Pacific, Thomas & Betts, Siemens, and General Electric.

In short, expect the major (and minor) companies to offer them. You may have a slightly difficult time looking for SWD suppliers online because only a few product listings include more detailed information that indicates whether the breakers are SWD listed or not. At least, I can say as much in most of my Amazon searches. eBay is an exception, though.

Conclusion

All in all, the SWD definition I discussed here proves the inherent connection between switches and circuit breakers. The answer to “What does SWD mean on a circuit breaker?” highlights the practical uses of breakers that can function like switches.

Can they take the place of a standard switch? Not really. Much like other specialized gadgets, they tend to shine the most when fulfilling their intended function.

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