NEMA L6-30 Meltdown

[mcgimpkins]

I've brewed 10-15 beers with this setup and have not run into any electrical problems until this. I started heating up my strike water in the garage, and walked away. I was grinding grains and talking to the wife when I heard a loud pop and the pump shut off in the garage.

Immediately upon entering the garage, I smelled electrical burn and burned plastic. I saw smoke coming from the wire above my GFCI, went to my breaker box and made sure the power was off, the 30 amp breaker had flipped. I unplugged everything, however I had to wear gloves to unplug the NEMA L6-30 from my inline GFCI, as it was too hot to touch. I got my camera to document it and have drawn up a wiring diagram. I had to use pliers to pull apart the NEMA L6-30 as the plastic had completely melted.

Has this happened to anyone? Do you think I had a loose wire? A faulty NEMA L6-30? I am not an electrician, however from everything I have read states I have wired my setup correctly.

At the moment I am not really sure what I can do and if I can salvage the NEMA L6-30 plug on the GFCI as it has a bunch of melted plastic on it.

See Pics below:

Wiring Diagram

Melted L6-30

Melted L6-30 Opened by pliers as the plastic had melted together

Entire Adapter Cable

GFCI L6-30 Plug with Melted Plastic on it:

 

[PapaFoxtrot]

From this photo, it looks like you had a failure of the connection inside the receptacle. How did you terminate the wires in there? Any "before" pic's?

 

[jcav]

Wow that's a lot of heat. I am glad it shut down in time and no one was hurt in the incident.

John

 

[dmcman73]

Yup...looks like a failed connection. I've seen that happen in other applications (not brewing). Plug was melted from either a wire being loose and oxidation formed between the wire and contact (very easy to do if current would arc between them) caused resistance which in turn caused it to heat up and severely melt or the wire just came loose and shorted out to ground or neutral.

In your case, there was a short. Check all of your circuits. Someone had a melt down when a wire in their heating element housing shorted out and blew out the SSR it was connected to.

 

[mcgimpkins]

Thanks for the feedback guys, prior to this I had more confidence in my wiring abilities, this is making me re-check and be more anal about things.

No I didn't document or take pictures of the build. I pulled apart the 3 way angled straight blade plug as I had wired that end and took pics of what I did there. I was assuming that a wire had gotten lose however I wanted confirmation.

I was able to salvage the male L6-30 on the GFCI. I hit it with a wire brush on a dremel tool and was able to get the melted plastic off of it.

Here are the pics of the 3 way angled straight blade plug, I see some lose strands of wire on the black:

Cleaned up male L6-30 on the GFCI by using wire brush on Dremel Tool

 

[The10mmKid]

Without having the connector in my hand the following may be untrue.

From the pics it appears that the plated gripper is installed backwards.
Notice how it is angled under the screw! (screw only making contact on one side)

I think those notches should be pointed down and the grip flipped over. The notch is made to prevent the grip from rotating when the screw is tightened.

Could be wrong.

'da Kid

 

[WI_Wino]

I'm not sure I would try to salvage the male plug. The plastic looks suspect to me.

 

[Bobby_M]

It looks like the wrong stripper size was used also and a good number of strands got lost.

 

[dmcman73]

Without having the connector in my hand the following may be untrue.

From the pics it appears that the plated gripper is installed backwards.
Notice how it is angled under the screw! (screw only making contact on one side)

I think those notches should be pointed down and the grip flipped over. The notch is made to prevent the grip from rotating when the screw is tightened.

Could be wrong.

'da Kid

i believe they are on correctly, the angled parts should angle away. To stop them from rotating the angle parts rest against the plastic body of the plug.

What I do notice is a lot of strands all over the place and in fact, the black 'HOT' lead has quite a few strands just sticking out from the bottom. That means that there is a lot of pressure on the few strands that are clamped down and as Bobby pointed out, it looks like the wrong wire strippers were used, a few of those strands that are clamped could have nicks in them as well.....making them weak and a few tugs on the plug could cause those to give out which might be what happened on the other plug.

Cut all the wires back on all of your plugs and use the proper sized wire stripper for that gauge wire. Once you strip them back, use your fingers and twist the strands just so they stay together and then put them into the grips. There should be no strands sticking out at all and the wires should be clamped as close to the insulation as you can (look at the black hot lead in your pic).

 

[dmcman73]

These are the wire strippers I use and they work very well, goes down to 10 gauge for stranded wire and they are only $11.00 at Home Depot: http://www.homedepot.com/p/Klein-Tools-6-1-4-in-Wire-Stripper-Cutter-11045/100630729

 

[mcgimpkins]

Thanks for the replies everyone. I'll make sure that I am using the correct stripper size, twist the wire and don't have loose ends.

From the pics it appears that the plated gripper is installed backwards.
Notice how it is angled under the screw! (screw only making contact on one side)

I think those notches should be pointed down and the grip flipped over. The notch is made to prevent the grip from rotating when the screw is tightened.

i believe they are on correctly, the angled parts should angle away. To stop them from rotating the angle parts rest against the plastic body of the plug.

If anyone has a picture of the correct way the wire should be put in the plates, please share it. I would like to ensure I am connecting everything correctly.

 

[dmcman73]

Here you go: [ame]https://www.youtube.com/watch?v=CVRctvCcyPQ[/ame]

It's for a welder but same plug. He suggests also soldering the wires at the ends to prevent them from getting crushed, which yours are. He states that the plug he has (which is the same one you have) were made for solid wire and not stranded wire, which is why he suggests soldering the exposed end. Do you have a soldering iron or know someone who does?

The tabs on his are facing outwards just like yours are, like I said, it's so it hits against the plastic body so they don't rotate.

 

[DVilleBrewing]

Judging from the pics of the assembled straight plug, with all the missing and stray wires, you would have cut down the effective wire size, from say a 8 gauge to possibly a 10, or 12 gauge wire. This COULD possibly have caused the connection to overheat and melt, as it would not be able to handle the amperage. Just a possibility.

 

[kal]

It looks like the wrong stripper size was used also and a good number of strands got lost.

Yes. I noticed that as well. While there may not have been many strands cut, it certainly doesn't help, especially if there's a loose connection as well.

Hard to see from the pictures but looks like the wire bundle may have been overtightened or wrong size cord grip used (some can be flipped over) when you put the male plug together (?). That could have damaged the wire inside as well effectively reducing the wire diameter.

To add to what others have said:

Heat is created when current flows through an area that is too small to handle the amount of current. This can happen:

(a) with a loose connection where only a few strands are making contact because the wire is not properly tightened/fastened, and/or
(b) a wire that is too small to handle the current is used, and/or
(c) when a properly sized wire is used but some of the copper strands were cut/trimmed to get it to fit (this should never be done), or
(d) if an electrical socket or blade is dirty or charred or if the plug is not pushed and locked in properly with the receptacle.

All of these cases effectively reduce the contact area meaning that more current flows through a smaller area which in turns creates more heat which can melt the insulation on wires and damage nearby components.

It could also be that you’re actually pulling too much current by using oversized heating elements. This would only be possible if an incorrectly sized breaker was installed in the electrical panel (larger than 30 or 50 amps, depending on your control panel size) as otherwise the breaker would pop if more than 30A or 50A was pulled. A 30A or 50A breaker must be used (sized for your control panel).

I may also be a bad part, but that's rarer.

Kal

 

[FuzzeWuzze]

In this case because there's space shouldnt he just put properly crimped ring/spade terminals on these connections and screw down on those and call it a day?

I made sure that there were no connections in my entire setup that weren't using crimped connectors for this very reason, properly terminating by just screwing down onto bare wire rarely gets you a solid connection compared to a crimped ring terminal unless i guess if your a professional electrician and have years of experience doing it.

There's so much bare wire just floating inside that pictured outlet its scary and honestly not too surprising something shorted.

 

[BrunDog]

As stated, looks like an insufficient termination job.

DO NOT re-use any component involved in an electrical fire/overload. Everything is compromised and should be eliminated.