Aqualink RS Power Center line in melting at lug.

[washcycle]

The line in to my power center keeps melting. The only thing that changes is a VSP pump and a voltage surge protector all on the same side.

Any one have ideas on what is going on?

I'm trying to get an electrician to look at it too, but I am an EE and don't mind a DIY if it seems reasonable. Just don't know what the root cause is here.

 

[ajw22]

You say keeps melting. How many times has it melted and been repaired?

That lug screw logs like it has a lot of corrosion. At this point it may have high resistance at the connection. And as an EE you should remember that high resistance will draw more amps and heat.

What size is the wire and CB feeding the panel?

 

[1poolman1]

The line in to my power center keeps melting. The only thing that changes is a VSP pump and a voltage surge protector all on the same side.

Any one have ideas on what is going on?

I'm trying to get an electrician to look at it too, but I am an EE and don't mind a DIY if it seems reasonable. Just don't know what the root cause is here.

It is easy to not tighten the lug enough on stranded wire. It may have been bad from the initial installation. If this is not the first time this happened, as ajw22 said, the build up of corrosion keeps making the problem worse.
If the wire was simply stripped but not cut back to clean copper, the problem will continue, even if the bus and lug are cleaned well.

 

[JamesW]

Is this a neutral connected with your ground wires?

You don't do that on a subpanel.

The hot leg connection is getting really hot.

How old is the system?

What was done the last time it melted?

Do you have a thermal camera you can use to look at the connection when it is repaired?

Can you measure the amperage when everything is running again?

 

[1poolman1]

Is this a neutral connected with your ground wires?

You don't do that on a subpanel.

The hot leg connection is getting really hot.

How old is the system?

What was done the last time it melted?

Do you have a thermal camera you can use to look at the connection when it is repaired?

Can you measure the amperage when everything is running again?

View attachment 438407

Good catch. Most people don't realize how danerous that can be.

 

[washcycle]

You say keeps melting. How many times has it melted and been repaired?

That lug screw logs like it has a lot of corrosion. At this point it may have high resistance at the connection. And as an EE you should remember that high resistance will draw more amps and heat.

What size is the wire and CB feeding the panel?

Only once, I cut out a section to clean copper and used the same lug. I didn't clean those connections at the lug so there could have been built up corrosion adding resistance. I'll pull the lug screw and give everything a good cleaning.

The wire doesn't have markings. Looks like it's big enough though, it's pretty beefy 4 or 6 AWG?, but I'll measure the diameter tomorrow to be sure.

Looks like someone might have caught a neutral on the ground bar, not sure that's the case but will check it out tomorrow.
This panel has been a hot mess since I moved in 2 year ago, didn't have GFCI protection, nothing was bonded. Pool company installed VSP and GFCI circuit for me. I added the SPD protection.
There is a SPD voltage protector and the waterfall pump on that side of the breaker. I can't imagine those are causing this. I like the corrosion idea. The weather seals were not in good condition and I replaced those last week. I have a feeling a good scrub to remove corrosion and redo the wire again to clean copper might do the trick.

 

[washcycle]

Cleaned the contacts real good and reconnected everything back up and running. I am checking daily to see if there is any overheating. So far so good.

 

[generessler]

Cleaned the contacts real good and reconnected everything back up and running. I am checking daily to see if there is any overheating. So far so good.

I think you got this right. This looks like classic arc damage. A slightly loose connection starts arcing, which heats the wire and carbonizes anything in the area, which coats the connection with soot, which attracts moisture, which causes corrosion, which makes the the arcing worse ... over and over in a cycle until the wire burns through.

I have seen this happen three times in 2 years of ownership of my 16-year old RS Aqualink box: a circuit breaker, a pump relay, and a wire nut.

It normally happens because the sparky who wired it didn't make the connection tight enough. Torque spec on those screws is usually around 36 inch-pounds. That's a pretty hefty twist. Some use dielectric grease to keep oxygen out. Probably overkill, but unlikely to hurt.

 

[JamesW]

Get a noncontact temperature reader or an infrared camera and check the operating temperature.

 

[generessler]

Get a noncontact temperature reader or an infrared camera and check the operating temperature.

Oh, nuts. Now I want one. Very, very cool. Never used to buy anything for myself before the pool

 

[JamesW]

Very, very cool.

If you get the FLIR, you will know exactly how cool.

It's cooler than liquid nitrogen.