Houston...we almost had a big problem

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Triple9

Active Member
Joined
Mar 18, 2011
Messages
43
Reaction score
5
Location
Melrose
Started heating my HLT up today and went upstairs while the water was heating. Went to check on it about 15 minutes later and noticed the smell of plastic in the air. Shut everything down, opened up the toolbox that holds my panel and a bunch of smoke comes out. One of the terminals is melting and probably would have started a fire if I waited much longer.

I'm using a pretty standard configuration. 30 amp breaker at the Box, spa panel, 5500W Camco heater element. Leviton 2626F 30 amp locking receptacle as well as a leviton 30 amp locking plug. Wires appear perfectly fine, not blackened.

Only thing I can think is I hadn't tested the GFCI recently, it failed and a terminal wire loosened. I've brewed around 7 or 8 batches without issue with this setup.

Any other thoughts about what might have happened and best way to rectify it?
 
Glad you're ok. That's pretty scary.

Which terminal was it that melted exactly?

A loose connection is a real possibility. Was it a crimp connector? The reason I ask is because there's been some discussion about weak crimps and this kind of thing happening.
 
Yeah, not the greatest feeling thinking about what could have happened.

It was one of the hot wires and right at the receptacle, so no crimp. Screwed down.
 
We are going to need to see some pictures of this, for education purposes of course.
 
My first thought is the wire wasn't connected well enough.

With a decent amount of current flowing, you want to make sure every connection is cranked down tight, and has a lot of metal-to-metal contact.

Also, the wire-around-the-screw connections really need to be done with solid wire. Stranded really needs terminals crimped on, or at least tinned.
 
Ok, dismantled it and here's what we have. I do believe i will switch to solid core when I put the new receptacle in. Thanks for the heads up. I have a ton of it lying around, so should be an easy fix.

image-3205895783.jpg


image-2094042395.jpg
 
Ok, dismantled it and here's what we have. I do believe i will switch to solid core when I put the new receptacle in. Thanks for the heads up. I have a ton of it lying around, so should be an easy fix.

Loose terminal screw.

I see it all the time at work. I'm an electrician, and stranded wire is better than solid in my opinion. my .02
 
Only thing I can think is I hadn't tested the GFCI recently, it failed and a terminal wire loosened. I've brewed around 7 or 8 batches without issue with this setup.

Any other thoughts about what might have happened and best way to rectify it?

GFCI has nothing to do with it.

Loose and or inadequate wire connection. I wouldn't use the solid wire, but I would make sure there is the proper amount of wire in the terminal and that the terminals are tightened properly.

I'd also recommend to re-tighten the terminals after one batch, then check them again after another couple batches.
 
Also, the wire-around-the-screw connections really need to be done with solid wire. Stranded really needs terminals crimped on, or at least tinned.

I don't believe those are around the screw connections. Insert and tighten the screw, which clamps the wire.

Also, tinned wire under screws can/will be problematic as the solder will cold creep under the pressure and will lose the contact pressure. A light tinning of the tip of the wire to maintain shape is OK, but if the end is fully tinned / solder has wicked up the strands that's when you have the cold creep problem.
 
Not me, but I do have access to a thermal imager which clearly shows poor connections (under load).
 
Thanks for sharing. It reinforces the requirements for solid connections and serves as a lesson for all of us wannabe electricians.
 
When tightening your terminals use a slotted (flat head) screwdriver. Its hard to get enough torque with a phillips screwdriver
 
Scary. I will re-tighten all of my connections immediately. Thanks for sharing!
 
In hindsight, I think installing the receptacles in the panel and then installing the wires might have contributed to the problem. Smaller space to really torque everything down well. This may be a good opportunity the break down the whole 240 side of the panel and tighten it up.
 
Wow, the side view looking at the screw looks like the jacket was still on the wire and looks like its outside of the clamp. If that's the case you may want to recheck all your connections. Each fitting/receptacle if you look real close has a template that tells you how far to trim back the wire jacket.

Thankfully you went back to check on it and prevented a fire.

Be Safe, Castermmt
 
Wow, the side view looking at the screw looks like the jacket was still on the wire and looks like its outside of the clamp.

Yeah, it sorta does, doesn't it? Hard to say if that's what it is or if it's just really charred there.

Point being though, yes, use the strip gauge on the back of the connector and ensure to get all the wire strands but no insulation in the clamp.
 
Ok, dismantled it and here's what we have. I do believe i will switch to solid core when I put the new receptacle in. Thanks for the heads up. I have a ton of it lying around, so should be an easy fix.

I was wrong!!

That isn't the kind of connection I was picturing when I was talking about solid vs. stranded wire. That one probably would be better with stranded.

Still, the problem looks to be the same.. As a rule, it is important for connections to be tight (with lots of metal-metal contact). And as a previous poster said, I also like to use a flat screwdriver to crank the screws down as tight as I can.
 
Back
Top