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In North America we commonly use power strips to connect equipment to the building.

https://en.wikipedia.org/wiki/Power_strip

I noticed that some power strips have a circuit breaker, and some do not.

I have worked at facilities that required all power strips to have a circuit breaker. They did not specify size of the breaker, leaving me expecting that there's some standard governing the size of the circuit breaker on power strips. What is it?

A circuit breaker does not seem to be required by UL, since I find UL-listed power strips without circuit breakers all the time.

What is the risk of using a power strip without a circuit breaker? If there's no risk, why do any power strips have them? And when power strips have a circuit breaker, what is the typical trip value of that breaker and is there any code/guideline that governs it?

As long as the power strip uses internal wire that corresponds to the plug on the power strip (i.e. it has a 15A plug and uses 14Ga wire throughout, which is sufficient for 15A), it seems that the circuit breaker in the building would protect both the installed wiring and the power strip wiring from any overcurrent damage. In this case a circuit breaker of 15A would be redundant, and a circuit breaker over 15A would be ineffective, and a circuit breaker under 15A would be unnecessary.

If the power strip uses undersize wire, then I understand the need for a breaker. Undersize wire is permitted by UL for appliances. For example, a lamp cord is permitted to use 20Ga wire even if it has a 15A receptacle on it (I will never understand why this is permitted, but it is. Any appliance with a cord size insufficient to support max current of the plug type should require the cord to be protected by a fuse in the plug, but in fact there is no such requirement AFAIK). If a power strip uses undersize wiring, the cord could be melted, and a circuit breaker would be required to protect the cord or internal wiring. However, I don't know if all power strips with circuit breakers have undersize cords, or if all power strips with undersize cords have breakers (I would hope so).

BetterSense
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  • Can you be clear about what you mean by "power strip"? – Andy aka Jun 28 '23 at 17:49
  • The text of UL1363 may be of help if you can get ahold of a copy, at least in relation to US standards. There are also rules about not using things like extension cords and perhaps power strips in "permanent" installations, that are more under the heading of code than UL standards. – Spehro Pefhany Jun 28 '23 at 18:04
  • Many cheap power strips bought online catch on fire when conducting less than the legal 15A. – Audioguru Jun 28 '23 at 20:55
  • Too much meandering in the question. I don't know what I would want to address. And if I did address something, I'd miss saying something about a dozen other details you wrote about. But I do have one thing to say. @Audioguru has it right about cheap power strips. Buy one and take it apart and look inside. If that doesn't scare you... nothing will. Then open up one of [these](https://tripplite.eaton.com/isobar-8-outlet-surge-protector-12-ft-cord-3840-joules~ISOBAR8ULTRA) and compare the differences. It's not perfect. But it is a lot better. – periblepsis Jun 29 '23 at 00:15

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