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JPR
07-18-2006, 07:13 PM
this is not the first time I have seen this, but still seems silly and scary. Almost makes one think that you should install a fuse to protect the fuse. And no, the fuse it not blown.

http://img.photobucket.com/albums/v228/jpr2004/fuse.jpg

Evan
07-18-2006, 07:27 PM
That's pretty common with any sort of connector that carries high currents. All it takes is a bit of resistance at the connector and a lot of heat is generated. I see motherboard connectors on computers that aren't working right that have several of the pins severely overheated and the plastic plug has turned all brown and crumbly around those pins.
Take out all the other fuses and re-plug them. It will help clean the contacts.
I would replace the connectors for that fuse as the metal in the connector may now be annealed and have no grip. It's asking for trouble to just stick in a new fuse.

CCWKen
07-18-2006, 09:57 PM
Ditto on the resistance. Also make sure the 30A fuse is proper for the slot. You could be smoking wires.

wierdscience
07-18-2006, 10:21 PM
Did you have a new stereo installed lately?Some of those "audio-pro's" are good at causing that sort of thing.

My boss had an alarm installed on his Isuzu box truck,it worked great,until I tilted the cab to check the anti-freeze:D

Idiots didn't run the wire from the fuse block up to the hinge and then back,they just clipped it in and ran it straight up to the door post.

RobDee
07-18-2006, 10:41 PM
Put them in with conductive gell.

Wareagle
07-18-2006, 11:52 PM
That is most deifnately a resistance issue! Evan is on the money.

In a truck I used to have, the A/C circuit was doing that same thing. I bypassed the fuse block and installed a circuit breaker to protect the A/C. Worked like a charm.

My advice would be one of two things, rework the fuse holder (maybe bypass it like above), or make sure you have fire coverage on your insurance!

JPR
07-19-2006, 12:38 AM
The car is complete original down to the factory radio. I assume the problem was caused by dirty contacts like Evan said. Probably not a bad idea to pull all the fuses and clean them. On Thursday, I plan on installing a new fuse holder or breaker.

Wareagle
07-19-2006, 12:43 AM
JPR, good luck with the car. Look at the bright side, at least you have a burnt fuse, instead of a burned out car!

J Tiers
07-19-2006, 08:36 AM
I think his point is that the fuse was not protected against the condition it is supposed to protect the rest of the wiring from.... i.e. overheating and resulting fire.

The only protection the fuse had from that was the fact (we hope) that the plastic it is encased in (as well as fuse block) is non-flammable.

With a chinese made fuse (is there still another kind?) that "fact" is only a "possibility".

Hey, the fuse is a very cheaply made product.... as cheap as possible, and the manufacturer pounded the vendor for a few less cents per thousand pieces.... They had to cheap out SOMEWHERE. This time it was on the contacts.

Evan
07-19-2006, 10:25 AM
As I said, it's very common. Fusible links are supposed to be the weak link in the circuit and operate by getting hotter than the rest of the wiring. It doesn't always work. I once almost had a house fire because the circuit breaker on one of my electric baseboard heating circuits didn't blow. Just behind the heater the 220 wiring had been pinched and was just barely touching ground. Not enough for a solid connection but enough to smoke the wiring. I had smoke coming out from behind the heater.

Xerox had an interesting method of dealing with blown fuses in certain applications. In some machines the light source for the imaging system was a high intensity fluorescent bulb powered by a high frequency power supply. Sometimes the power supply would fail and blow a fuse on the circuit board. To convince the customer to call for service and to make it easy for the technician to determine the problem the fusible link on the board was coated with a material that produced that unmistakeable "brown smell" that you get from a fried transformer.

When that fuse blew there was no doubt in the customers mind that something had gone badly wrong. This was to stop them from continuing to try and make copies since the copies would come out black and that would cause damage to the fuser system if more than a few were made. We usually would find the machine unplugged with a big BROKEN sign on it. Very effective and should be used more often.

J Tiers
07-19-2006, 02:10 PM
It IS worth noting that many of the old type fuses would have had a pretty good chance of opening with that sort of heating..... Most fuses, being heat-operated devices, have ratings pretty sensitive to ambient temperature.

The rating "in-use" may be much less than that marked, if the holder allows the fuse to heat in the way that fuse did. Fuse companies (good ones) show that data.

BUT, because that particular type fuse is often located in a fusebox inside the engine compartment, the fuse would have to be designed to operate successfully in very hot conditions. Therefore it might be a higher melting point fuse material, which would make it somewhat less sensitive to a change of rating by overtemp.

And, there is a good chance it was also over-rated deliberately to prevent blowing unless really shorted.

Obviously the heating evidenced by the picture was not sufficient to bring the effective rating below the current it actually had flowing.......

bigbill04
07-19-2006, 03:10 PM
Hiya Guys. I just wanted to let some of the guys know how important a good electrical connection is. Evan is exactly correct when he says how a loose connection causes higher resistance and arcing which will heat the wire and anything else connected to it. About ten years ago, we had a similar situation in my basement electrical panel that could have led to a tragedy. The breaker panel was very old and was manufactured by Federal. I wanted to install a small electrical heater in my living room, since at the time we did not have central heating. Our only heat supply was a combination gas stove with a heater box on the side. I went to the local hardware store for a 220 volt, 20 amp breaker so I could hook the heater to, but was informed that the Federal Company no longer produced these breakers. The salesman did have one, but the price was $50. I told the guy that a brand new Murray box with 10 20 amp breakers can be bought at Lowe's for $79. Me being very frugile, cheap, decided to just use the small ceramic heater that we had been using until I found the need to change the old panel. That following summer our pool pump suddenly quit working. I immediately thought that maybe the breaker had blown. I went to the basement and the breaker was fine. I removed the panel's cover and to my surprise, all the neutral wires, the white ones, had a good majority of the plastic insulation burned off. The neutral leading from the pool pump's breaker got so hot that it had melted the copper and that was why the pump was not working. I spoke to an electrician friend of mine who had been one of my Sears Auto Center customers and he asked me if my basement had drastic temperature changes. I told him that it did and he explained why this had happened. The expanding and contracting of the copper wires over time had loosened the screws holding the wire to the neutral, ground buss. This looseness allowed the wires to continually arc, create a higher resistance, and finally heat the wire to the point of melting. He further told me that this condition would not make the breaker pop, like I would have thought. He also mentioned that Federal breakers were known for not working properly and suggested that I change the box. I did change it one Sunday afternoon with a Murray panel that I bought at Lowe's for the reasonable price of $79 plus tax. Murry breakers cost about $5 each as opposed to $50 for an old Federal. Since I have installed my gas forced air heating system, I no longer have to worry about the screws loosening up from the temperature fluctuations. I do, however, still check the tightness of the screws every six months. So far so good. So guys, take note of this situation and always make sure that you have a nice and tight electrical connection. Also, use an anti-oxidant compound, such as OX-GARD, which is available at Home Depot or Lowe's, on all your wire connections. This stuff will guard against oxidation, improve conductivity, and make a cooler connection. Good luck guys and play it safe. Sincerely yours, Bill Senko

J Tiers
07-19-2006, 05:39 PM
The neighbors have a "Federal" box, and they have to flip breakers every so often to keep circuits "on".... apparently the breakers "open" from corrosion and/or heating, although they don't actually trip......

I'd have replaced it long ago.....

Wareagle
07-19-2006, 07:28 PM
Those old Federal breakers are bad news! bigbill04's problem is a very classic example of that. They are notorius for not tripping under fault conditions, the contacts in the panels are not very good, and replacements are expensive. Under a fault condition, they just melt down (most of the time). If anyone out there has one, it would be advisable to replace it as soon as possible. There is a reason that Federal Pacific is out of business!

Electrical panels and devices do need maintainence. Every year a re-torque of all of the connections in the panel would be a good idea. Plugs should checked for contact tightness, in other words will the outlet hold a plug without it falling down or out. Switches should have a distinct 'feel' when the position is change, and there should be any sound or arcing (or sight). If there are any suspect issues, then look at the wire and see if the insulation is burned, brittle, or discolored. If so, then that should be addressed as well.

Disclaimer here: Make sure that the power is off to any panel or device prior to performing any work. If you aren't sure of something, or don't understand how to do something, then by all means consult a qualified licensed electrician. Failure to turn power off prior to performing a task on an electrical system can cause injury or serious death!

bigbill04 made mention of using and anti-oxident compound on all of the connections. If you are using copper wire and connections that are rated CU-AL, then you don't need the compound (you can use it if it makes you feel safer). If you have aluminum wire, then regardless of the connection rating, the compound is recommended, and copper pigtails to the devices are a good idea.

Sorry to have taken this tread another direction!

Evan
07-19-2006, 07:37 PM
Every year a re-torque of all of the connections in the panel would be a good idea.

Sounds like a bad plan to me. You will end up mashing the wires and possibly damaging the connector threads to the point where it will cause a problem. Maybe check them every ten years would be an idea but not every year. The connectors and the wires are designed to have the same coefficient of expansion with temperature so they don't loosen.

That was the main problem with aluminum wiring. People would install aluminum using copper rated receptacles and breakers. Differential linear expansion would then mash and loosen the conductors until they caused a problem. If you use the correct parts that won't happen.

Wareagle
07-19-2006, 07:50 PM
Sounds like a bad plan to me. You will end up mashing the wires and possibly damaging the connector threads to the point where it will cause a problem. Maybe check them every ten years would be an idea but not every year. The connectors and the wires are designed to have the same coefficient of expansion with temperature so they don't loosen.

That was the main problem with aluminum wiring. People would install aluminum using copper rated receptacles and breakers. Differential linear expansion would then mash and loosen the conductors until they caused a problem. If you use the correct parts that won't happen.

All of that is true except the connections still back off from expansion and contraction, regardless. It is recommended to do a torque and check every year. If you did it every two, three, or five, then that is better than not doing it at all! This is not to put a 'half turn' on every connection each time. Some will need it, some won't. As long as you do not over torque the connections, then you won't mash the wire into pieces.