So, how's your fire insurance and smoke detectors? - Just asking... no reason.

Seriously, things like this shouldn't melt down. We can't fully troubleshoot what went wrong, but you need a good explanation of what happened.

I'm seeing wires that appear to have overheated at the terminals over time. I don't know if this is excess current, poor connection, aluminum wire that wasn't properly terminated, etc....

My advise would be to photograph it, then have an electrician explain what happened and replace the box / wiring. Then go back to the installer and make a financial claim.

it's a cold week in the 30s-40s degrees here in Gainesville, FL

I gather you don't have a heat pump and you are using electric heat strips to keep the house warm. Florida has recently had usually cold weather so I imagine you are operating the heating much more than you normally would. This could explain why wire connections have melted and failed.

They said also that they don't like the wiring, there are cables of different materials wrapped up together. They said they can replace the box but I would have to sign a waiver that if the box fuses again I will have to pay again for a new one.

When the AC and heat strips were installed in 2019 did the installer make any wiring changes to the box that has failed? If changes were made, then can make an argument that the box failed due to poor workmanship and/or materials. If the installer did not touch this box, then I don't see how you can make any claim. The best you can do is accuse him of not checking the box and telling you a new one is needed.

I don't understand the part about the waiver. I question what type of repair you were going to get for $250. You should hire a licensed electrician to fix the problem. I don't think you need to rewire the house. The electrician can give you his professional opinion.

Good suggestions from Jake. The Trane A/C may be warranted for 10 years, but the disconnect box that melted is not from Trane, that is a locally installed item. It may have been new with the new A/C, but it may also have been an old box (old A/C). Either way, it probably isn't warranted after 2+ years. What is certain is that the disconnect box melted from poorly made electrical connections inside it. You may have to pay to replace it no matter what. Also, that is not an old breaker panel. Square D QO boxes are good stuff, and you have an electrical inspection sticker on it which is dated 6/03, when it was probably installed.

Get someone to fix it properly, ASAP. Don't play games asking someone else to pay for it - your house is going to burn down before that happens!

I agree with sktn77a: get a qualified electrician to remedy any deficiencies in the electrical installation. Most HVAC contractors have limited abilities in their own trade--let alone another trade.

It looks like the wires that burned are in a pull plug type disconnect? One problem I see is difference in wire gauge the leads are going to the plug are smaller wires than those they are wire nutted to.

Typically HVAC contractors are allowed to install this type of disconnect even at the tech level. But the wires must be large enough to handle the load.

The same can happen with loose connections. If the company installed this disconnect, typically these parts are 1 year only, because they are considered accessories or parts external to the equipment. If the disconnect wasn't replaced during install of the equipment, it should have at least been inspected for integrity.

That said the breaker did it's job, tripped and shut the equipment off. Burned wires are more common than you would think. However, an ounce of prevention is worth a pound of cure. It wasn't hooked up with proper materials to handle the load it's connected to in my opinion.

Another possible problem I kind of see, but not 100% sure from what you show...

If it were me at this point I would carefully remove the electric panel to see if you have aluminum wiring. If that's the case the house should be rewired in copper wire. The only reason I mention this is that the ground wire (green lead) looks like it's attached to aluminum wire. Typically if the ground is aluminum so are the hot legs.

click to enlarge picture below.

We can't really tell the root cause of what went wrong from the photos.

I see a number of things that I would look into (the size of the wire, the connection to the disconnect, if it was a mix of aluminum and copper).

What we do know for sure is that this wasn't a minor problem, it was a significant failure - the type that starts fires. I'm not as flip as "The breaker did its job..." . There was very significant overheating of the conductors and connections over time before the circuit went into overcurrent and the breakers shut down.

Have an electrician replace the branch circuit from the breaker box to and including the disconnect. Have them inspect from the disconnect forward.

Take photos and save the melted disconnect, the wires going to the disconnect and the wire nutted connections to the existing wire (I'd cut the existing wiring so I could keep all of that intact.

I would go after the HVAC company for compensation AFTER the electrician fixed things.

They could have burned your house down. They don't learn to do things differently unless there's a consequence for doing poor work / bad supervision.

A note about the aluminum wiring issue that Austin Air brought up:

The big problem with aluminum wiring was connections with outlets and such on branch circuits. Properly installed aluminum wiring when used for feeders generally weren't the issue. The reason is that the larger feeders connected to lugs that were designed for aluminum wire and were properly cleaned, anti-oxidant applied and the lugs properly tightened.

Your electrician can advise you on your panel. If there is aluminum branch wiring you will want to consider replacement. Again - if the wiring to outlets and such are aluminum, that's the highest risk.

Aluminum circuits to furnace / water heater / stove / dryer should be inspected at the terminations for overheating / oxidation as well as making sure anti-oxidation compound was used and the lugs are tight. These circuits are low-moderate risk as long as they were done properly and were not improperly modified. Aluminum wires can not be wire nutted with copper wire as I believe was done on your installation. Consider replacement of these circuits particularly if any updates / changes are going to be made or have been made.

Large aluminum service entrance cables should be inspected at the terminations for signs of overheating / oxidation (aluminum oxide is white) - but service entrance cables are much lower risk because they were typically installed properly. The electrician should also look for anti-oxidation compound and insure the lugs are still tight.

Any new circuits - such as the one to your furnace / AC should be done in copper just to avoid issues.

Ok so I have an update. Electrician came yesterday, I was not home, unfortunately. They repaired the box. AC works. They called me and said they measured the voltage and got 100 V, I should have 240 V. They said to call the provider (mine is GRU) and tell them I don't get 240 V. GRU just came today and they always measured 240V, both at the outside compressor and the meter. But GRU said the meter cables are bad and maybe i could experience a drop in voltage (or the electrician instrument was bad). GRU said I definitely need to upgrade the meter to a 200 miter can. I already got a 200 amp breaker and service inside. I need thicker wire (200 amp 2/0) from meter to breaker. Breaker has a spot in which 3 wires are connecting at the same spot (one is the neutral) and GRU said it is probably not up to code and should be changed. As for aluminum wiring, he checked the AC box and he said that it is the neutralnot aluminum! He said the neutral is copper with some other minerals so color looks different but definitely not aluminum. So i guess it was the inexperienced guy. He unscrewed the breaker and said he doesn't see aluminum coming out of the breaker.

"Bad" wiring doesn't cause a drop in voltage from 240 to 100. The AC wouldn't run on 100v. And 240 isn't the same as 110 - someone is making a mistake somewhere.

None of this information sounds right. Either you aren't reporting it back correctly or the electrician doesn't have a clue. You can be excused for not reporting it back correctly -- not so much the electrician.

I'd want a written report of what was found - so things don't get lost in the retelling. Putting it in writing has a way of cutting out the BS also.

I'm with Austin Air - the existing wires appear to be aluminum in the photos. I say that based on the neutral as well as the small amount of the red wire I can see. In addition, the gauge of the wire looks larger than the new copper - which is consistent with aluminum wire.

You called in an electrician AND the utility. There should be no guessing. There should be no "maybe his meter is bad". There should be no "probably not up to code".

There are copper conductors, there are aluminum conductors. There aren't "copper with some other minerals". It's been a while since I cracked a copy of the NEC - but I'm pretty sure THAT hasn't changed.

"Bad" wiring doesn't cause a drop in voltage from 240 to 100. The AC wouldn't run on 100v. And 240 isn't the same as 110 - someone is making a mistake somewhere.

A bad connection could be resistive and cause a voltage drop. The resistance causes heat. This could explain why connectors and wires have melted. The breaker doesn't trip in these situations since the current flow is not exceeding the breaker rating. The voltage should have been measured under load conditions. The electric heat strips would put out heat even with a resistive connection but it would be less than its nominal rating. We don't know if the air handler is wired to a 120 V or 240 V circuit so it may be unaffected by this problem.

Tinned coated copper wiring does exist. It looks like aluminum wire but it is a copper conductor. Perhaps this is what the electrician was trying to say. However you want to be absolutely sure there is no aluminum wiring without a proper connector. Resistive and melted connections are signs of aluminum wiring. Don't assume anything.

The undersized wire from the meter to the main circuit breaker needs to be changed ASAP. Whoever did the electrical upgrade did not get a permit or inspection. That wire can get very hot and cause a fire. Have a licensed electrician inspect everything and make the required repairs.

@mike_home

The point is that none of this info sounds right. Indeed a bad connection can cause voltage drop, but if you have a 50% or more voltage drop, you are going to have equipment that doesn't work and wires that are melted. Other than the obvious meltdown - they don't have that.

The only time I've seen tinned copper house wire is in much older wire #12 or #14.

They hired an electrician. They should have gotten someone who knew what they were doing.

If I were on a job like that and noted undersized service entrance wire, I would have documented it in writing - to protect my company if not the homeowner. If there was a more than 50% voltage drop, I wouldn't have walked away from the job without knowing why and putting it in writing.

I don't believe the 50% voltage drop either. Something is not right. I think we are in agreement there are serious electrical problems and they need to be addressed. This is beyond a fix for an HVAC installer to come back after 2+ years and do a free repair.

I agree. No HVAC fault here. Electrical guys should call me any moment to come back asap. The numbers are right. I have a voicemail left from the electrical guy that says 100 V. I played that on the speaker to the GRU utilities guy. The GRU guys said: no way at first, he said the instrument has to be wrong. Then he saw the corroded wires in the meter and he said that "maybe" there could have been a drop to 100V but very unlikely. GRU guy swore that that wire in the AC box that melted as well as a wire in the breaker looks like aluminum but it is not, it is copper with some other metal in it (I guess tinned coated copper wire). But thank you for the suggestions, I am gonna make sure to tell the electrician to check all the wires in the house and get rid of aluminum if found. I let you know how it proceeds.

I don't think anyone said "No HVAC fault here." I sure didn't.

What they said was that it was beyond a warranty period and you shouldn't expect the HVAC guys to have the technical ability to fix the electrical. I agree.

Look, even if you have upstream wiring issues that doesn't explain the melt down in that disconnect. I wouldn't let that go with the HVAC guys because I think they f'd up and they shouldn't be given a pass.

A note about the aluminum wiring issue that Austin Air brought up:

The big problem with aluminum wiring was connections with outlets and such on branch circuits. Properly installed aluminum wiring when used for feeders generally weren't the issue.

Well 'connections' are always the weak point. The comment about the breaker did it's job? what do you think the breaker is there for? If condition warrants it to pop, it should pop -- if it doesn't "for whatever reason" is pointless... the result is fire. Most of the time a breaker will trip due to over amp event, a direct short to ground or opposing live circuit is an extreme version of that.

The picture about aluminum "connections" that I posted previously represent a 55 times greater fire risk. There is always a risk of fire, but it is minimalized when connections are contained within an electrical box along with proper breaker etc. If the breaker isn't proper you either have nuisance trips or a breaker that will not trip when it's supposed to. (outside of a direct short to ground or short between L1 and L2 --- a short between L1 and L2 is the worst it could potentially take out a feeding transformer. Note I said *could*.)

So if alumuninum conductors (wires or connection points) are 55 times more likely for problems does this mean that copper wires or connections points don't have problems?

No. (having copper connections is merely cutting your risk.) A picture of a recent service call in which a copper wire burned at the connection point. It's always connection points. Unless of course someone is doing something and they cut wires or something. In the example below power was still live when I arrived.

click to enlarge.

Ok so I got the quote below (click to enlarge). I removed all personal information. Does it seem reasonable? Are they doing everything they are supposed to do? Should I ask them if they can also check all the electrical connections in the house (of course that would cost more). And one question: I am upgrading to 200 Amp, why does the quote say: Dp 100 Amp QO breaker? Also, GRU guy said "they will probably also try to charge you the breaker, the breaker is fine no need to change it". But maybe this piece is something that needs to be changed.

@Austin Air Companie

I went into detail regarding aluminum branch wiring - which is hazardous vs aluminum feeder wires - which are significantly less hazardous when installed properly. Not everyone can (or should) rewire just because they have aluminum feeders, for example. If you are replacing things anyway, do it with copper. It's worth noting that the overhead residential service drops installed by the power company are aluminum - and they aren't bursting into flames.

I understand exactly what a breaker is there for. A breaker prevents overcurrent conditions that last for more than a fraction of a second. They don't protect against overheating due to undersized conductors or high resistance connections. Those conditions can (and do) start fires without the breaker ever tripping because there isn't an overcurrent situation. Sometimes the overheating results in a short circuit and the breaker tripping before a fire, not not always.

The photos were a very good example of what appears to be bad workmanship causing high-resistance overheated connections with a very high likelihood of fire and the breaker not intervening until very, very, very late in the game.

The first line of defense against hazardous conditions (and HVAC failing) is knowledgeable workers who adhere to code and practice good workmanship - which is why I wouldn't let these HVAC installers off the hook. They almost burned the house down.

@venexiano

Regarding the quote:

The work in the quote is very limited in scope. It's replacing just from the weatherhead to the meter base and includes a 100 amp wires and breaker. It's a reasonable but limited solution to the immediate problem. I think the price is reasonable.

It does not replace the wire from the meter base to your inside breaker panel or increase your breaker panel to 200 amps - if that's what you were intending.

Note that they are proposing to install aluminum feeder wires.

Options:

1. You could ask them to quote it with copper conductors

2. You could ask them to size it for 200 amps (and copper conductors) but install a 100 amp breaker. This would give you the option to update the rest (from the meter base and the panel) to 200 amps at a later date. At that time you would also replace the new 100 amp breaker with a 200 amp.

3. You could ask for a quote to update the entire service to 200 amps including a new panel. If the inside panel is sketchy, or if you intend to buy an electric vehicle, you may want to update the panel to 200 amps.

Thank you. Questions:

1) Where did you see they are proposing to install aluminum wire?

2) I do want to buy a second hand Tesla in 2 years after I save some money. So 200 amp is good. But as I said, the Utilities guy said with his own words "You are lucky cause you bought a house with a 200 amp breaker and 200 amp service inside. you need to upgrade to 200 Amp meter can. You need bigger wires from meter to breaker, the 2/0 that are 200 amp". I just took pictures of the breaker cables. The label on wires coming from the outdoor meter into the breaker says I/0 so 100 Amp as the Utilities guy said. @Jake The Wonderdog, why did you say "increase your breaker panel to 200 amps"?

3)@Jake The Wonderdog, why does the quote "includes a 100 amp wires and breaker" as you said? I clearly copied and pasted to them the Utilities guy's words, which I just quoted to you on item (2) above.

The outside meter is bad, I saw it with my eyes. Basically, I'm just making sure they are charging me for things that need to be done. And if I think more things need to be done then in the quote, I am happy to pay more to make my house a safer place, any suggestion is welcome! Thank you very much for helping out!

On your quote, Line 8 from the top: SE32 USE Cable AL 2-2-4-6 100A wire

That is Service Entrance Cable - "AL" is aluminum - 2-2-4-6 is the gauge of the wire which is the size for 100 amps using aluminum conductors.

I can't tell from your photos what size your main breaker is - is there a label on it anywhere that says 100, 150 or 200?

The wires going to the main breaker do not look like 200 amp conductors from the photo.

200 amp conductors require 2/0 gauge wire in copper - and those are over 1/2" in diameter including insulation. They are big.

Can you take a photo of the writing on the cables where I have circled?

That will tell me the size of the wire.

Also look for a main breaker rating in amps - and or take a photo of the label on the door that says "QO Load Center" so I can look up the model.

@venexiano

Ok, I re-read your post again:

1. I answered that: The quote you have is to install 100 amp #2 aluminum wires from the weatherhead to the meter base and install a 100 amp outside disconnect. (AL = aluminum CU = copper)

2. If your existing wires from your meter base to your panel are 1/0 - they have the capacity for 150 amp service. (100 amp service is #4 copper or #2 aluminum, 150 amp service is #1 copper or 2/0 Aluminum, 200 amp is 2/0 copper or 4/0 aluminum)

3. I don't know why they spec'd 100 amp service on your quote. If you intend to have an electric vehicle I'd want a 150 amp service minimum and would default to 200 amp. A fast charger is 40-50 amps and you have to size the circuit so that the load is no more than 80% of the circuit capacity. A 48 amp fast charger would require a 60 amp circuit. That, and some combination of electric heat, water heater, range, dryer would put you over a 100 amp service.

Not everyone can (or should) rewire just because they have aluminum feeders, for example. If you are replacing things anyway, do it with copper. It's worth noting that the overhead residential service drops installed by the power company are aluminum - and they aren't bursting into flames.

Ok, I'm not an electrician so the term "feeder" isn't what I was referring to. My understanding is that the feeder is a much larger connection, in which lugs or terminal connectors are used as the connection point. If that's what you mean, sure. It's much less likely for those to fail.

That being said, I've gone to homes missing one leg of power at the service entrance. How much larger are those connections? Transformers on poles do occasionally burst into flames.

So to say that certain wires aren't bursting into flames, is all subjective.

Aluminum wire connections are not a problem if they connected to aluminum Problems occur when copper connectors are used. The dissimilar metals create oxidation creating heat and eventually a fire. Aluminum has a higher coefficient of expansion which causes connections to loosen faster and speeds up the process.

The electrician is probably quoting aluminum to keep the costs down. I agree with Jake that everything should be copper. It were my house I would spend the extra money and not have to worry about it.

The existing circuit panel is full. You are not going to be able to a circuit for the car charger. You should explain to the electrician your future plans and upgrade as needed. See how much extra it will cost to have 200 amp service. If the house is all electric you will need it.

The best thing on the quote is the $100 permit fee and inspection. Hopefully everything will be done to the current code.

I don't know the rules or customs in Dubai, but do you own the home or are you renting? If you're renting, it should be the landlord's problem and if you own, then it's yours.

mtvhike, I think the post is not very cleverly disguised spam.