2-pole circuit breakers

ericbakuladavis

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Jul 10, 2021
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Hi Folks

I have MakeSkyBlue 60A MPPT charge controller. The manual calls for two 2-pole circuit breakers to be installed like this:

msb.png

For the breaker between the battery and the controller, for example, I assume it would work to have a single-pole breaker on the positive wire only...

Is there an advantage to having the positive and negative wires connect to a breaker?
Does the 2-pole breaker just add redundancy?
Would it be just as good to have a single-pole breaker on the positive wire and another single-pole breaker on the negative wire?
Would it be just as good to have two single-pole breakers in a row on the positive wire?
 

JoeHam

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Welcome to the forum!

This has been discussed before without a firm conclusion but I always use double pole breakers. Be sure to use DC rated breakers from a reputable company not some amazon off brand crap.

Safety devices is no place to save money, especially on a $20 item.

It’s a cheap upgrade IMHO.

See here :

 
Last edited:

rmaddy

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Be sure to use DC rated breakers from a reputable company not some amazon off brand crap.
And for the breaker between the solar panels and the SCC, make sure the DC breaker (whether single or double pole) is fully rated to handle the absolute Voc your panels can produce at the absolute coldest temperatures you may encounter.

For example, three panels in series might create over 130Voc, depending on the panels. You don't want a plain 48V breaker unless you want sparks and flames coming out the breaker.
 

ericbakuladavis

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@JoeHam Thank you. I am compelled to offer the standard disclaimer: "I searched the forum but didn't find it." You did though! Thanks for providing the link to that discussion. I will dig into that later.

Safety devices is no place to save money, especially on a $20 item.
^ Sounds like wisdom.

@rmaddy Thank you. Sounds like good advice. I have some 250V DC breakers. Hopefully, they don't turn out to be Amazon off brand crap 😬
 

Short_Shot

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When I'm doing control wiring it's virtually mandatory. Though I still see many devices come in without it... different debate.

If I'm doing something *for myself* that's mobile and low voltage and low current I may skimp this on some devices.

That said. If you accidentally connect the positive wire to accidentally bypass that switch without any faults at all, you'll suddenly have a complete circuit and current. Sometimes this current can be substantial and you most likely won't have a strong connection right out of the bat. This can cause a rather severe arc, some arc flash, hot molten metal in your eyes, etc.

I will agree with the first comment that it's always better to be on the safe side. Especially when the difference between damage, injury, or death is just a few dollars and will agree with that recommendation to just use them anyways.

I'd definitely recommend this as a panel disconnect.
 

JoeHam

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The C65H-DC 250v breaker (as in your link) is the model I look for.

At times I have received Schneider brand from that seller even though not advertised that way.

Schneider, Midnite Solar, Blue Sea are known brands.

T-Tocas is an example of crap off brand stuff.
 

Short_Shot

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Schneider is definitely a trusted brand in my book. Literally saved my life once (480vac baby), but then I've not got a large sample size to fall back on.
 
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