Burnt up junction box

[JAS]

Hi all,

I have my (2) 335 Watt Solar Panels mounted on the side of my garage. I used a Cutting Edge Power Entry Housing (https://www.amazon.com/gp/product/B07MMWKR29/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) to bring the wires in through the garage wall. Inside the garage, I used a simple plastic junction box to connect the wires from the Entry Housing assembly to a 10/2 Romex wire running to my MPP Solar AIO.

For the last 6 months, I had the panels wired in series with no issues. Last week, I changed the panels to be wired in parallel (to gain more power into the MPP unit. This change successfully got me about 100 additional watts from the panels.... For about an hour, before things went up in smoke (see attached).

I guess, it could have been a coincidence with the change in panel orientation. But, it seems like the increased amperage got things too hot. But, here's what has me stumped...

The Entry Housing is supposedly rated for 30 amps. According to my Solar Assistant, I was only seeing about 15 amps from the panels at the time of the incident. (The panels can't produce much more than that anyway). From the looks of the aftermath, it looks like the issue started at the Wago Connectors (which are also rated for 30 amps).

The only thing that I can think happened is that I had put ferrules (https://www.amazon.com/gp/product/B08J7M8X49/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1) on the 10awg wires from the entry housing and maybe the ferrules didn't make a good connection inside the Wagos?

I'm going to replace the junction box with a metal box now. But, I'm nervous about whether I can still use the entry housing and remaining unburnt wire and whether I can still use Wago's (or just twist with a wire nut)? Either way, I think I'll leave out the ferrules.

Thoughts?

 

[John Frum]

Are those wagos 41x or 61x?

 

[JAS]

Are those wagos 41x or 61x?

Not sure, there's a picture on the Amazon listing... looks like it says 221

EDIT: Actually, the one pic I posted shows what is remaining of the one Wago... It's a 221

 

[John Frum]

Not sure, there's a picture on the Amazon listing... looks like it says 221

The 4 means 4mm2
The 6 means 6mm2

 

[OzSolar]

The 4 means 4mm2
The 6 means 6mm2

Why does it matter? Both are rated for 32 amps continuous.

 

[John Frum]

Why does it matter? Both are rated for 32 amps continuous.

It probably doesn't.
Just curious because I'm using the same junction boxes, with Wago 221-41x and 221-61x.
Probably with ferrules.

 

[Think About It]

I wouldn't use a connector that's not UL listed. Also the connector should be listed for the correct conductor type AL or CU or both. The connector most likely heated up to due a high resistance connection. (Bad splice) The wagos don't look like copper.

 

[John Frum]

I wouldn't use a connector that's not UL listed. Also the connector should be listed for the correct conductor type AL or CU or both. The connector most likely heated up to due a high resistance connection. (Bad splice) The wagos don't look like copper.

They are ul listed.

 

[John Frum]

Why does it matter? Both are rated for 32 amps continuous.

The 41x series is only rated for 20 amps.

 

[Luxpower_Gilbert]

solid wire is a big no!

 

[MurphyGuy]

There's a video on youtube showing what garbage wago connectors are. They used a thermal camera to show them heating up because of the poor connection they make.

 

[OzSolar]

The 41x series is only rated for 20 amps.

Good catch. 20 amps for UL. Just checked and I was referring to the IEC rating printed on the side, 32 amps for 41x and 61x is actually 41 amps.

 

[OzSolar]

I'm going to replace the junction box with a metal box now. But, I'm nervous about whether I can still use the entry housing and remaining unburnt wire and whether I can still use Wago's (or just twist with a wire nut)? Either way, I think I'll leave out the ferrules.

I strongly suspect that ferrule was your problem. I'd replace the box, leave out the ferrules and use Wagos again. I've used a ton of Wagos and never had a problem. I'd also leave the lid off the box for while and inspect it regularly for a few weeks just because.

Here's one of many video's showing that Wagos and wire nuts are just fine.

 

[Mattb4]

I am of the wire nut generation and only recently began to use Wago's . One thing I have observed is you really have to get sufficient insulation stripped and the wire fully inserted into it. If the Wago grabs onto any insulation you will get a poor connection and if the wire is not fully inserted (Wago brand have a clear back so you can check wire insertion) it can pull out easily. I also have my doubts that using crimp on wire ferules would be a good idea to use with either the wire nuts or Wago style connectors.

 

[BiduleOhm]

Don't use ferrules with wagos, they're not made for those. The wagos accept single and multi-stranded wires directly.

 

[TomC4306]

I don't think I'd use Romex from that box to the inverter. What inverter? What does the manual say about using solid core wire?

 

[Bluedog225]

I don’t understand how a proper ferrule would cause issues. With a couple of points/questions,

Was it ferrules on solid wire? If so, why?

And those ferrules look super sketchy. I like the solid copper ones from ferrules direct. You can visualize what’s going on. I just can’t imagine them hurting things as they gather up all the loose copper strands into a nice tight bundle.

Glad it wasn’t worse.

 

[Mattb4]

Out of curiosity, and being constrained by really lousy weather today, I decide to do a test of ferrules on 10awg THHN wire and found that I could not get an adequate insertion into a WAGO. Being as the WAGO is designed for up to 10awg wire this is not surprising since the addition of the ferrule makes the wire diameter size larger.

 

[John Frum]

Don't use ferrules with wagos, they're not made for those. The wagos accept single and multi-stranded wires directly.

Why do you think Wago lever nuts are not made for ferrules?
Do you have a citation?

 

[Hedges]

I like Ideal set-screw wire nuts.
May not be good for joining two different size/type of wire, however. In that case, maybe ferrule would be good for stranded that will be connected to solid, but I haven't tried.

Set Screws - Other - Wire Connectors - Product Type

www.idealind.com