[BenjiWiebe]

The issue wasn't heat generated by excessive current, but heat generated by excessive resistance and normal current.

Mag breakers and fuses won't help. A thermal fuse could work,provided it was thermally bonded to the bad connection. So you'll need a lot of thermal fuses - one at every potential bad connection.

[1970-01-01]

Mag breaker opening under overtemp condition:

https://www.youtube.com/shorts/thUbyzO8Cek

[theamk]

This only happens when there is an overcurrent condition. As OP, scrumper, BenjiWiebe all told you there was no overcurrent condition. The system was rated for a 100 amp, the current was under that.

The thermal overload breaker won't help here, because it only trips when the current is above breaker rating. And one would install at least a 100A breaker into a circuit rated for 100A, or it'll just trip all the time.

(You can see the detailed curve on datasheet, example page 2 here [0]. It is surprisingly slow - for 1.5X overload, it takes >10 minutes to trip).

The problem was because of bad connection on 100A line. We can talk about mistakes made here, but lack of breaker was not one of them.

[0] https://www.eaton.com/content/dam/eaton/products/electrical-...

[1970-01-01]

>This only happens when there is an overcurrent condition.

It happens when it gets too hot. Principle of Operation: The Bimetallic Strip Mechanism:

https://www.haipart.com/news/thermal-trip-unit-in-circuit-br...

[theamk]

have you actually read this page?

> If the current exceeds the rated load for a prolonged period, the heat causes the bimetallic strip to bend.

> The unit trips after a delay inversely related to the magnitude of the overload; the greater the current, the faster the trip.

The heat is generated by the breaker itself, from the current. Maybe it'll trip slightly faster if the wire is very hot, but I say it's unlikely - the thermal resistance on a regular breaker is very low, and wire is not a very great heat conductor either.

And even if breaker was for some reason reacting on wire temperqture? Look at the original post. You can easily see how far the heat traveled simply by seeing where the insulation got blackened. It looks like just a few cm - nowhere close to get to the other end of the wire, which was in the breaker. The system had breaker, and it could not detect this condition.

(There are special "thermal fuses" which react on the external temperature, but they are very distinct from the regular circuit breaker, and they must be attached directly to the device emitting heat, like a motor. No one attaches those to the regular terminal strips)

[1970-01-01]

>The heat is generated by the breaker itself, from the current.

Why do you think this?

>You can easily see how far the heat traveled simply by seeing where the insulation got blackened. It looks like just a few cm

Why do you think this? Copper is excellent at thermal conductivity, only beaten by silver.

[theamk]

I have tested the thermal breakers multiple times, the wires are barely warm. Also your link says:

> When electrical current flows through the circuit, the strip heats up due to resistive heating.

This picture [0] from post ("Toasted Wires") shows the temperature damage. As you can see, the insulation damages was only at the very end of wires. Most of the wire are intact, meaning only the very end heated up. The other picture [1] shows the same

[0] https://i0.wp.com/inthewilderness.net/wp-content/uploads/202...

[1] https://i0.wp.com/inthewilderness.net/wp-content/uploads/202...

[BenjiWiebe]

Also, btw, the 'mag' part of the breaker is irrelevant. The magnetic component is for sudden large overcurrent events, to provide a quicker break than what a bimetallic strip can do.