Burned DC fuse holder and cable (Grid tied)

[squelch]

Hi everyone,

just happend recently

hope you can help me found out the reason for this one. see attachment

in this scenario, is it loose connection ?

based on your experiences,

TIA

[solarix]

Definitely a loose connection in there somewhere. Probably can't figure out where now. Once the plastic melts, the contacts start to move around and get worse. In the old days of "hard" plastics like bakelite, they did not melt so easy, but these new pvc and pe plastics are not near as tough. Still, one of the terminations probably did not get tightened well. It is something that is hard for inspectors to catch and why you want a good, detail oriented electrician. This kind of burned connection is the cause of lots of fires. Europe has gone to spring type terminations in order to not depend on the skill of the installer so much. I'm not real confident about those either. This whole problem is why the code is moving toward arc fault detection as it would have caught this failure earlier....

[squelch]

Thanks Solarix,

is thermal scanning monitoring can detect this loose connection before it happens/future prediction. its been running for 3 months now.

[DanS26]

If one of your connections was loose enough to cause this...then there is a HIGH likelihood that there are other loose connections in other parts of the system. I would highly recommend that you have your installer prove to your satisfaction that all connections are torqued to the proper manufacturers specifications.

He needs to use a properly calibrated torque screwdriver on every connection. Sadly most electricians do not use torque tools on smaller connections and just go by feel.

[Smitty]

+1 on the loose connection

[squelch]

If one of your connections was loose enough to cause this...then there is a HIGH likelihood that there are other loose connections in other parts of the system. I would highly recommend that you have your installer prove to your satisfaction that all connections are torqued to the proper manufacturers specifications.

He needs to use a properly calibrated torque screwdriver on every connection. Sadly most electricians do not use torque tools on smaller connections and just go by feel.

Yes, torque screwdriver would be great. is it out on the market ? im also not aware of that.

[DanS26]

Yes, torque screwdriver would be great. is it out on the market ? im also not aware of that.

Are you a DIY'er? If you made these connections, then go to Lowes or HD and get the proper tool. Cost about $100.....don't play with fire.

[Mike90250]

Amazon has a great gunsmiths torque screwdriver that takes hex bits, so slot, square, star, hex, phillips, posi-torque can all be handled.

With fuses, you get an extra failure point, the grip fit between the springs and the fuse body, a little resistance, it gets warm and oxidizes, gets warmer and oxidizes more....... I see the upper fitting is a bit smoked too, which leads me to think gripper fit, not the wire clamp.

[squelch]

guys, what should be the normal temp of the termination ?
ambient temp 30 C and im getting 50 C on the terminations , is this normal ?

[Mike90250]

guys, what should be the normal temp of the termination ?
ambient temp 30 C and im getting 50 C on the terminations , is this normal ?

Nope, connections should only be a degree or two warmer. I have to get 30amps going to show a degree rise.

[squelch]

my reading is 26A dc
so the possibility of heating this up is the loose connection issue ?

[SunEagle]

2 wires on damaged fuse holder

Is there any reason why there are 2 wires connected at the bottom of the first 2 fuse holders and only one wire on the other fuse holders?

Just thinking that besides a loose connection you might have exceeded the amp rating of that fuse holder.

[sensij]

Is there any reason why there are 2 wires connected at the bottom of the first 2 fuse holders and only one wire on the other fuse holders?

Just thinking that besides a loose connection you might have exceeded the amp rating of that fuse holder.

Not just amp rating, but fuse block terminations are usually rated to accept only a single wire. Putting two in almost guarantees a poor connection. If you really need two wires going into the fuse, using Twin wire ferrules is one good way to do it.

[SunEagle]

Not just amp rating, but fuse block terminations are usually rated to accept only a single wire. Putting two in almost guarantees a poor connection. If you really need two wires going into the fuse, using Twin wire ferrules is one good way to do it.

Good point.

Two wires on the same terminal connection can heat differently and expand at different rates causing motion and a loose connection.

[Sunking]

Is there any reason why there are 2 wires connected at the bottom of the first 2 fuse holders and only one wire on the other fuse holders?Just thinking that besides a loose connection you might have exceeded the amp rating of that fuse holder.

Not to mention compliance and workmanship issues.