I'm glad to see this brought up. I had one disconnect box get a little toasty and melt the pull out switch. I looked it over and the only damage area was the switch connector, so I just figured it was a cheap box, made cheaply, and it failed of its own accord, especially considering the switch was fully and tightly pushed in. I just placed a new one on a hot water heater and the thing is even cheaper than the one I bought a few years ago. It amazes me how they can make these boxes so cheaply.
I used to see this a lot with air conditioner disconnects supplied with aluminum wire in Phoenix. Aluminum wires worked loose with heat cycling. Need to annually tighten lugs.
Great info! Same thing happened with my house's power meter box. Some of my lights were flickering and dimming, especially when high amp draw appliances like the oven were running. I checked the voltage at the breaker panel while the lights were flickering and I found that one of the hots had low and unstable voltage. I called the power company and the guy who came out found that one of the clamps in the meter box was loose and not making a good connection with that prong on the back of the meter, it actually got so hot that it burned the back of the meter. He squeezed it with his pliers so it clamped the meter's prong tighter and replaced the meter and I haven't had any problems since, but after seeing this video I'm thinking he probably should have replaced the meter box or at least that part of it.
@@carlmccoy662 I called the power company about this earlier today and they offered to give me a new meter box for free. They won't install it, but they will shut the power off for free so I can change it. I haven't had any voltage drop problems since they "fixed" it, but I am going to change the box out anyways since it won't cost me anything other than a trip to go get the box and the time it takes me to change it out.
Great video. Fuses, terminals, wires, etc don't just burn up like that and need a quick tightening or fuse replacement.... The disconnect is now bad, terminal is bad, etc... Replace the overheated parts or it'll happen again.
Perfect I hace a failure on my entrance switch and the fuse looks the same, I was thinking an overload but the current was ok, so the problem as you said, its in the terminal . By the way, the amount if the fuses changet til now its the same as the price of a new switch.Thanks
Looking at the bottom fuse clamp it is rotated slightly clockwise causing it to contact the fuse at 10 and 4 o'clock only rather than along the full sides of the fuse. This reduced contact area caused the overheat condition.
repeated night dew in unsealed outdoor juntion box does speed oxidation of all metals including the fuse holder. These contact surfaces were designed to meet basic residential grade. These days most products are engineered to purposely fail predictably in a non-catastrophic way... ✌️
I work on commercial dish machines and they were having this issue, they replaced the disconnect and had no issues for about a year. Now it’s happening frequently. I tested the total amp draw of the machine and it wasn’t enough to blow the fuse. Could the disconnect go bad that quick?
If the fuses are burning (not just blowing), either you have wiring connections that are not tight, or the disconnect is just failing. You could try using a disconnect that utilizes a breaker. They generally are of higher quality. GFM
Very valuable. Have a question that probably seems dumb. Can the heating/melting happen even if the AC is not on? I found a disconnect box was warm, then found exactly what you described inside. But the AC unit has not been on--not in a year!
I found this video very informative! I have an older style home that I just moved into. It has one main service panel using circuit breakers, and 2 separate subpanels. Immediately after the main service panel with circuit breakers, is a sub panel with 2 30-amp cartridge fuses in a metal box with metal closing door. After this sub panel is another that is located in the detached garage with 2 20-amp glass fuses. My question to you is about this middle sub panel with 2 cartridge fuses. The box these cartridge fuses are housed in does not have a raised bump to attach a ground wire and screw. Instead, the bare copper wire is just sitting there in mid air. Doesn't that need to be connected to anything? Could I tap a hole in that metal box and attach a green ground screw and wire to that? How are the outlets in the garage still working with no ground connected to them? (Garage wiring has confirmed 12/3 wire)
The only time you need a fused disconnect is when you are tapping into a feeder with a higher ampacity. Normally the circuit breaker in this panel provides the overcurrent protection. There's no need for fuses In the disconnect if you already have the appropriate sized breaker in the panel feeding the disconnect.
40 years ago that would be correct. Since then, a fused disconnect is required. I don't know if that is an NEC requirement or if it is Wa state code. GFM
@@grayfurnaceman You only need a fused disconnect at the location if it says "maximum fused" not "maximum over current protection" on its name plate. Otherwise breaker in the panel is sufficient, and you don't need a fused disconnect. It's part of the UL listing as per art. 110.3 in the NEC. Nowhere does it state that there has to be a fused disconnect in NEC art. 440. It must be in the WA state code.
some burnt wire ends and lug terminals would have been a good visual, also explaining and showing not to try and clean overheated wire either, just cut well past any burnt or replace the whole line
Because the fuse is supposed to protect wireing inside the structure by blowing b4 the wires heat up enough to burn the structure also fuses need to be rated 5 amps below the breaker ratings ie 30 amp breaker 25 amp fuse and and so forth. it's also used as a service disconnect.
It has alot to do with the distance from the breaker panel as well. If panel is not within eye sight, a disconnect is required as I understand it. I'm no electrican by trade though.
They MAKE disconnects without fuses, but it's hard to find vendors that carry them. I live in California, and could find NO reason why fuses would be required. The disconnect is a required safety shut off, to protect a technician working on the unit (if somebody turned the circuit breaker ON, technician would still be protected, because the disconnect is within sight of the AC condenser unit).
My disconnect is a switch rather than a pull-out. How do I check the fuse? Do I just need to replace the entire switch? Also, one wire I see going in is discolored. Does something need to be done with that wire?
You probably have a breaker for circuit protection rather than a fuse. A discolored wire to the breaker is probably from a loose wire overheating. It may have damaged the breaker. GFM
@@grayfurnaceman I prob still need to fix the wire issue, but I tightened some screws on the contactor and got power but no fan movement. Looks like I didn’t push the fan hard enough because when the electrician came, that’s all he did to get the system running again. However, he did say my motor is bad and that it will probably stop working again soon. He didn’t do any diagnostics at all though. Is a bad fan motor diagnosed by visual/sound only? I actually told him on the phone I think it’s a bad motor :(
@@RJP7093 If he had to physically push the blade to get the fan to run, you have a bearing problem or a capacitor failure. If the fan does not move easily with the power off, it is a bearing problem that is easily diagnosed by attempting to rotate the fan. GFM
@@grayfurnaceman I had just changed my capacitor before calling electrician(old cap was fine but then in testing Voltage from common to fan, Idk what happened but it killed the cap 🙁). But with the system off, I’m able to turn/move the fan easily. Before electrician came, I tried to move the fan with system on but it felt stuck (not at all like when system off) so I didn’t push harder. Hoping it’s ok now since the fan moves fine with system off? because the guy said if I don’t replace fan motor and fan stops running again, it could kill the compressor too.
GrayFurnaceMan, help. My outside condensor was running all night long while the thermostate was not calling for AC. I had to turn off the circuit breaker to the condensor to stop it from running. Why is this happening? The next day, I turned on the breaker, the unit work... for a few days and then it happened again.
grayfurnaceman not exactly sure what you mean by whole house fan. But my HVAC system is comprised of an AMANA 96% efficiency furnace connected to an outside AC condenser. That outside unit was stuck ON for god knows how long until I had to cut the breaker.
Oh, and the outside unit was not replaced with purchase of the furnace. It’s an older Carrier (I believe) unit that has worked for us over the past 7years.
Just thinking about your question again. The furnace fan can be turned on to run and circulate air if I chose to. But I don’t use that feature. So, the t-stat is idle for ac in the middle of the night while temps are well below the cool setting and yet that outside unit fan is just going. No cool air is being blowing from furnace as it is OFF. Touch the coil plenum it is cold likely iced over. That’s when I cut the breaker. Wait 2days before trying it again. And it worked for a few days, then stuck on again. Hope that helps.
If the indoor fan does not come on, the whole house fan is not the issue. The only issue I can come up with is the contactor in the outdoor unit is sticking on. Generally, if a contactor sticks on, it will not open even if the power is cut off. GFM
Thermal cameras is not the tool of the future it is a present day tool. I bought mine several years ago and now they are better and more for your money
Thermal cameras are a valuable tool that keeps your fingers away from terminals. You just have to remember the circuit must be under operation for at least 5 min before testing. GFM
@@grayfurnaceman in this case it would worth replacing the disconnect box and test the heatpump. maybe its OK. should i go with a fused box or none fused one? it seems like the none fused are more popular.
I agree. The most common one here is the Duck disconnect. I have always preferred a disconnect with breakers installed, but the price difference puts you at a disadvantage in the bid. GFM
I agree. Where I live a disconnect is required but it doesn't need to be fused. When I installed my mini split I used a non fused disconnect for reliability, the 15 amp breaker in the panel does the same thing making the fuses redundant in my opinion.
@@grayfurnaceman Redundancy would be my guess. Here in PA (Pittsburgh) a fused disconnect is not needed. However, some inspectors here won"t pass you if the breaker, inline with the disconnect, is 5 amps oversized for the load application. Even i the wire can handle it. Goodman 2 ton 13 SEER "Maximum circuit breaker ampacity" = 15 amps. I had it wired with 12-2 on a 2 pole 20 amp. Oh well, live and learn.
fused disconnect is kind of leftover from fused main panels, but also to help curb idiots from moving wires in the panel and double lugging a 50 or 60amp oven feeder, just to gain 120v branch circuits space. the rest of us install a subpanel or replace the undersized panel and entrance ;) I've seen countless times double lugging of 10 and 12awg and even 14awg wire with 6awg into oven/range feed breakers or off the panels direct bus bar lugs, so full main breaker current available. fused diconnect at th other end could potentially save a burnt house, though it's still not right.
You didn't do it tooooo bad but still. Not only do I find it completely unprofessional, but it's also extremely annoying in my opinion when people refer to parts and components of equipment as " this thing, thingy, this part, this doohickey etc... are you unfamiliar with the proper terminology and correct names of individual parts and components of the particular piece of equipment or just being lazy. When making an informative/educational video. I believe that it is crucial to include as much information as possible. Referring to everything by it's proper name can only be beneficial. Plus it makes you look more intelligent and professional
