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Wiring protection - circuit breakers

chorky

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So, I noticed something today that I probably should have noticed a while ago but didn't for some reason. Circuit breakers and their rated voltage.

I have been looking for a variety of breakers (mostly because I prefer the reset ability over blown fuses) for future upgrades but just realized today while looking at some from Blue Sea that there are a wide range of voltages.

Of course there are the 24v varieties for those types of systems. However, nearly all breakers I have looked at for the amp rating I am wanting are listed as 48v. It doesn't specify if that is just the 'capacity' it is able to handle, or if it is rated for a 48v system (honestly never heard of a 48v system anyway.....). The ones I have currently do not have a voltage rating on them, which puts them into question....

Here is an example, just a random link
https://www.amazon.com/GLOSO-Waterp...c81b35-5c8e-4874-9f00-c5f4bea838b9-spons&th=1


So I went over to the blue sea systems group of options and looked at a 30a breaker. It is listed at a 12v system
https://www.amazon.com/gp/product/B000KOVBXQ/ref=ewc_pr_img_2?smid=ATVPDKIKX0DER&th=1

However, when selecting a 150a breaker, it automatically switches to list as a 48v system
https://www.amazon.com/gp/product/B000KOVC12/ref=ewc_pr_img_2?smid=ATVPDKIKX0DER&th=1

They are both the same 187 series

So, I went over to blue seas' website. And things got even more confusing. The same 30a breaker listed above via amazon is now shown to be a 48v breaker
https://www.bluesea.com/products/7136/187-Series_Circuit_Breaker_-_Surface_Mount_30A

So I peaked at a different series, and its also listed as 48v
https://www.bluesea.com/products/7188/285-Series_Circuit_Breaker_-_Surface_Mount_120A

So at this point, I'm pretty confused.... Can anyone enlighten me please? I can't be the only one who has noticed this because hundreds of people are using this style of breaker to protect their wiring. But its making me wonder if it's even actually providing protection at all.
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chorky

chorky

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Ok so since this is bothering me so much I went and looked at blue sea fuse blocks that I have used in the past for other things. Even those are listed at 32 or 48v. The only option I found in a very quick 5 minute search showed the following with the option of running on a 12v system.

https://www.bluesea.com/products/7725/SafetyHub_100_Fuse_Block
 

Kevin_D

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A typical automotive circuit breaker uses heat to trip. Heat is generated by current flow, not voltage. The rated voltage specifies the safe maximum voltage that the breaker (or fuse holder) will withstand.
Some trucks and agricultural equipment use 48V systems.

Also, my personal experience with automotive circuit breakers is that it's not uncommon for the breaker to take as much as double its rated current to trip.
I'll stick with fuses.

Kevin
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