diy solar

diy solar

Use a fuse - and wear safety glasses... This could have been very bad.

smoothJoey said:
I asked them and it basically needs "the birdhouse" to make it work.
You mean this one http://www.midnitesolar.com/product...=Breakers&productCat_ID=16&sortOrder=15&act=p ?
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Yes, that one. That sucks.. why couldn't it be tripped by some low voltage signal? That seems it would be perfect for a lot of cases.. manually be able to disconnect your battery, protection for the battery/cable, and be used by BMS to disconnect the battery.. I noticed they have no specs/info on the remote trip aspect of the breaker.. Surely there are others out there that could do this?
 
Just saw this as well: The MidNite Solar MNEDC250RT remote trip circuit breaker is not UL or ETL listed.
 
rhino said:
Yes, that one. That sucks.. why couldn't it be tripped by some low voltage signal? That seems it would be perfect for a lot of cases.. manually be able to disconnect your battery, protection for the battery/cable, and be used by BMS to disconnect the battery.. I noticed they have no specs/info on the remote trip aspect of the breaker.. Surely there are others out there that could do this?
Click to expand...
I can't remember the details.
The guy kept talking to me like I was an electrical engineer.
Maybe you should talk to them.
As I recall everyone I spoke to were very nice.
 
That looks good.. I've never heard of shunt trip breakers.. Why aren't people using those instead of a Class T fuse and separate relay?
 
MurphyGuy said:
Why? That's exactly what those breakers are designed to do.. and do it again.. and again.

No different than the breaker in your home's electrical panel.. The only difference is that they're bigger and designed to extinguish a DC arc.
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Actually, they aren't.
Breakers are designed to trip and interrupt modest overloads repeatedly, like 100 times.
Some are switch rated, OK for turning lights on and off.
And then there is AIC.

A 200A breaker will slow trip after some seconds or minutes delay up to about 1000A. Above that it does magnetic fast trip.
The slow trip is either thermal or a hydraulic delay of magnetic trip.

But when hit with something like 20,000A, it is spec'd to trip and interrupt current once. For consumer breakers, close again on a dead short and trip one more time. It should fail open, unable to close.
 
Hedges said:
Actually, they aren't.
Breakers are designed to trip and interrupt modest overloads repeatedly, like 100 times.
Some are switch rated, OK for turning lights on and off.
And then there is AIC.

A 200A breaker will slow trip after some seconds or minutes delay up to about 1000A. Above that it does magnetic fast trip.
The slow trip is either thermal or a hydraulic delay of magnetic trip.

But when hit with something like 20,000A, it is spec'd to trip and interrupt current once. For consumer breakers, close again on a dead short and trip one more time. It should fail open, unable to close.
Click to expand...

I was going to say something along these lines but you said it better, with better specifics than I would have had. Breakers aren't meant to be infinitely re-used.
 
upnorthandpersonal said:
If she did not have that fuse, this would have been a lot worse... Definitely worth the cost of the Class T fuse.
Click to expand...

... And if she uses a proper fuse holder (instead of bolting to cable and heatshrinking), replacing it will be even easier.

At least the cables appear limber enough to not put excessive bending force on the fuse. If coarse-stranded 2/0 AC wiring, would matter more.

When replacing her fuse, there will be unfused wires swinging about. Both ends can swing, so disconnecting negative cable at battery and opening switch at positive would make them cold. But not in that order - switch first then negative cable, or negative cable can short to any cell.
 
The incident in the video of the original post got me to thinking about my Blue Sea switch. Yep, the 3/8" studs on the back are exposed. Even a piece of electrical tape over the studs would be better than nothing. A cap would be nice, but it might stick out too far, which would make the switch difficult to mount.
 
HRTKD said:
The incident in the video of the original post got me to thinking about my Blue Sea switch. Yep, the 3/8" studs on the back are exposed. Even a piece of electrical tape over the studs would be better than nothing. A cap would be nice, but it might stick out too far, which would make the switch difficult to mount.
Click to expand...
Self-bonding silicone tape is a good alternative to vinyl electrical tape for insulating heavy hardware. It’s a bit thicker and since the tape only sticks to itself, it doesn’t leave behind that #%! mess of adhesive like vinyl tapes.
 
Hedges said:
Actually, they aren't.
Breakers are designed to trip and interrupt modest overloads repeatedly, like 100 times.
Some are switch rated, OK for turning lights on and off.
And then there is AIC.

A 200A breaker will slow trip after some seconds or minutes delay up to about 1000A. Above that it does magnetic fast trip.
The slow trip is either thermal or a hydraulic delay of magnetic trip.

But when hit with something like 20,000A, it is spec'd to trip and interrupt current once. For consumer breakers, close again on a dead short and trip one more time. It should fail open, unable to close.
Click to expand...
The GJ1 breakers have no thermal trip, its all magnetic.

I'd be surprised if her short circuit passed even 500 amps.
 
MurphyGuy said:
The GJ1 breakers have no thermal trip, its all magnetic.

I'd be surprised if her short circuit passed even 500 amps.
Click to expand...

Thermal is one way to get time delay, magnetic/hydraulic is another.

GJ1P, "hydraulic-magnetic", "The UL listed series GJ1P (UL489) models are available in a choice of fast, medium or slow response times"


GJ "magnetic/hydraulic" "time-delay"


What size fuse did she have? At 500A, a 200A fuse is expected to hold for 10 seconds. A 110A fuse is expected to blow in 0.01 seconds
Not sure how much resistance there was in the path; that is what would have limited current.

 
What do people think of using the Class T fuse inline without a fuse block, like she did?
 
Last edited:
curiouscarbon said:
prevent torque and strain and it’s probably maybe ok*

*i don’t know if it’s ok
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They would work ok if it wasn't a catastrophic short... but the tclass fuse is capable of shutting down a massive short, and without the proper block, the fuse becomes a flame thrower...
 
Supervstech said:
They would work ok if it wasn't a catastrophic short... but the tclass fuse is capable of shutting down a massive short, and without the proper block, the fuse becomes a flame thrower...
Click to expand...
Really? Thats both cool and terrifying. How does the block help that?
 
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