LOOSE WIRES CAUSE FIRES
Loose electrical connections result in high resistance, making it more difficult for current to flow. The end result is heat, damaged insulation, burned insulation, melted wires, melted terminals, melted terminal strips, fire and even explosions. We all know this to be true, right?
In recent months we have seen an unusual amount of problems due to loose connections though, and so we thought it might be a good idea to review the basics. A common problem is that the ring terminal on the end of the wire does not fit well on the terminal strip provided by the alternator (generator end) manufacturer. Frequently, the technician doing the hook up simply forces the terminal in as best as possible and torques the screw down to spec. The torque spec is right, but there is just a small fraction of the ring terminal making contact with the terminal strip. This results in high resistance and higher power consumption, at best, or potentially a fire and explosion.
An easy solution is to trim the terminal being used so it fits completely inside the terminal strip and makes full contact with the metal strip at the bottom. Of course, properly torqueing the bolt is still essential.
Some manufacturers, such as Northern Lights, design their terminal strips so the bare wire can be inserted under the nut, if the installer so chooses. That is an elegant solution because it eliminates one connection entirely. Let’s face it, the fewer connections, the fewer things to go wrong.
Just because the connection was made properly by the installer, or came from the factory already connected, does not mean that it never has to be touched again. Factory workers and their Quality Control Team are human too. Generators do come through on occasion with less than perfect, or downright loose, connections. One of the startup procedure checkpoints is to check ALL connections in the Junction Box.
Electrical connections, especially those that are attached with a screw or bolt are subject to becoming loose. This may be due to the terminal warming and cooling, vibration or both. This is especially common with aluminum lugs! Always schedule a follow up visit to check the bolt torque after installation. This is critical with aluminum lugs with larger wire conductors. If you will be unable to do the follow up re-torque (such as on a boat that will be leaving), advise the customer and note (in writing) that this needs to be done on your Service Report. If there is a fire associated with a connection you made or touched down the road, it helps with liability protection.
We have it on our Annual Inspection lists to check all electrical and ground terminals. It is surprising how often you find that you can get a quarter turn, or more, on screw or stud on some connections.
One other thing to consider when making connections in or around a highly corrosive environment (and let’s face it—whether it is a boat or land based application in the Caribbean, it is corrosive) is to use a coating of silicone, or di-electric, grease on both the wire in crimp connector and at the terminal connection. Silicone grease is non-conductive, but it will not burn or catch fire. It will however protect the connection from corrosion. It is even more important to properly torque the crimp connector, or terminal strip connection, when using silicone grease because you need that metal to metal connection to ensure the smooth flow of current.
Sometimes the most common and routine part of our jobs can be the part that creates the most potential for problems. Electrical connections, while easy and routine, can be real problems for you and your customer down the road. Be sure that they are made well, and are checked after installation an regularly thereafter.