Magnetic Starter: In Search Of The Elusive Ohm

Also when using Ohms to track down problems like contacts & conections. The closer to 0 the beter but as you can watch your meter the harder you push the probes into the conductor the farther the number will go down.

One more thing & this isn't to be mean but those crimps look really bad & with that kind of current flowing through them they will likely cause you problems down the road. I quit crimping those type of connectors years ago. Some may call it over kill but I slide the strain relife(the plastic on the end) down off from them, solder the connection, then slide the strain relife back up on it. I noticed one of the strain releifs was smashed out by the wire which stops it from doing its job.

I solder almost every conection I want to last more then a month anymore. If it is a solid strain being held under a lug or has a wire nut then that is an exception. If your using wire nuts some grease in it will help ensure it from failing as fast along with sealing the back with some tape. Just FYI in your feture indevers.
 
I also do prefer soldered connections, however, crimped ones can be done right.......it just takes a special crimping tool rather than the first set of vice-grips you find......
-brino

EDIT: I have no intent to disrespect the OP's methods. I was just trying to say that soldering is NOT the only reliable method. A good crimp is one that has the proper physical area of contact for the current required and one that makes a good air-tight seal to keep the contact area from oxidizing too quickly.
 
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Yelp. I always prefered the ones that put the small dimple in one side. I've never found a good set at a automotive store. HF used to sell a really good set for $3 but that was 20 years ago so I don't know if they still do or not. Those automotive ones will lose their grip & start arcing with that much amprage tho. Well probably start a small arc you can't see then lose their grip.
 
Wreck™Wreck said:
Human skin can have a resistance of many thousands or as little as 1000 Ohm's depending on environmental conditions, sweaty skin has less resistance then dry skin Etc. This is one of the reasons that one may touch an automotive starting battery with your hands and feel nothing. Someone with soft skin devoid of callus and plain worn out skin(my hands are in such bad shape that I am at the high end) may feel a shock when you would not. If the Wife/Girlfriend/ Significant Other complains about being lightly shocked by an appliance yet it never happens to you there is no reason to think that such a thing is not actually occurring, they can feel it and you can not, thanks Mr Ohm.
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I do electrical work for friends from time to time. One that sticks in my mind was a drier that would take forever to dry clothes and the guys wife claimed it would shock her occasionally. I went over to take a look and found the outlet was wired with one of the 110 legs connected to the outlet ground. This of course made the whole cabinet charged 110 hot as soon as it was plugged in. I got a tingle off it but nothing serious obviously. Point is that a wet hand touching the cabinet of the washer next to it that was grounded and the cabinet of the dryer would have been fatal. Yet it had not happened up to that point. Once the wiring was corrected the dryer operated correctly and of course was much safer. Point is that if you are not sure about doing wiring, don't do wiring. Those of us that know it, don't believe it to be some black art. We understand what it takes and how it's done, and it seems simple. Problem is that doing it wrong, can prove deadly. This was one of those situations that all the things needed to cause a fatal shock never got in the room together. Simple things like being dry and enamel paint on the cabinet kept a very dangerous situation in check. But grabbing a ground or neutral and a 110 leg feed is not typically something you walk away from.
 
Do not really know why but the Code frowns on soldered connections anymore preferring the indented pressure type of connector or mechanical pressure (screw) type. Just the opposite of some folks experience, I have had more trouble with low voltage crimped connection. Typically of the automotive sort. My thoughts being that the low voltage has less ability to force its way through a corroded connection. Hence the reason why wiggling the wires makes the light bulb blink. In that realm I also solder.

Please don't fall into the habit of thinking certain items should have a specific ohmic value. This was a fault of mine for many years when I first entered the trade. Two coils from different make starters may have a totally different ohmic value even though they are both rated for the same voltage and come from the same size starter. Just look for "I have a circuit", low reading, or "No I don't have a circuit", high reading to infinity value. There are only two ways to do things in an electrical circuit. Open or closed, it's on or off. If it is in between then that is what a true ohm reading is good for. In the case of a single phase motor when wringing out the windings the start winding will have a higher resistance (many turns of fine wire) and the run windings will read lower resistance (fewer turns of heavier wire). Although both windings are rated for the same voltage.

Ohms are what limit amps when pushed by volts. Too many, it does not work. Not enough and it burns up. Just enough ohms to drop the voltage to zero and all is great. Kind of the long and short if it and Bob's your uncle.

Now if you are doing electronic transistor type work then it is a whole different kettle of fish. Then ohms are really important because of the low voltage doing the work. A few ohms one way or another is success or failure. That stuff is way over my simple brain.

Merry Christmas Mr. Dog.
:idea:
 
Code don't like soldered connections for one reason, heat. If you solder and not crimp a lug on a wire and the lug gets hot the solder can get hot and melt. If the wire in the lug is no longer held in with the solder then it can arc, fall out and touch metal cabinets charging them and all other sort of bad stuff. Anything that is going to be expected to carry a significant load should also be terminated with an uninsulated lug and if any corrosion exists at the point the lug lands on, it will need cleaned and prepped before being connected. Crimping should be done with proper crimpers and not the dime store specials. Fully closed lugs should be used and again, not the cheap stuff at Harbor Freight if it's gonna be carrying 15 amps or more. It's so much easier to buy the right stuff and do a job once as opposed to doing it every 6 months because the cheap lugs keep failing.
 
Well said Keith Foor.

I actually still use the cheap open ones tho. I almost always use a small dimple in the solid part of the rolled connector to retain the wire then seal with soldier & usually shrink wrap & lastly plastic tape while the wrap is still hot to get a nice tight seal. I don't have to play by code at home tho. ;)

I also run larger wire then code most of the time. You never know when you going to need to hook something up that needs a little more power then you had planned & in a few things like plug in heaters it doesn't hurt to have a little more safety with them.

Only exception is my lights. When I write a light it is only a light that nothing else will ever be connected to. I don't like anything else on my light circuits. When I need to see I need to see.
 
One comment on crimping and soldering, there are many different approaches and specifications as to solder or not solder. In general, if you use high quality crimps (alloy copper or brass), a proper crimper and size the wire according to the crimp size, you will break the wire long before you can pull the wire out of the crimp. Different connectors require specific crimpers to completely squeeze down the wire so there is no void space. Some of the better crimps have an inner and outer crimp shell of different alloys, I tried to get the wire out of one of these and wire was fused to the crimp metal. One of the biggest problems with the inexpensive crimpers is void space, look at the end of the wire in the crimp and you will almost always see open space on one side of the wire. Never solder a wire and then crimp it, seems logical, but solder will cold flow or melt with any resistance and the wire will loosen exacerbating the heating.

Cheaper crimps are often steel, and do not flow or compress around the wire vs. a copper/brass alloy crimp. In the aerospace industry soldering crimped wire is a no no, main reason is that it does not allow the wire just behind the crimp to flex and will fail much sooner in a high vibration or movement environment. That being said, in the marine or a corrosive environment I have seen crimps fail due to oxidation. The Coast Guard bulletins on the subject recommended crimping then soldering in certain applications. In some cases some form of strain relief is used over the crimp and extending onto the wire to decrease bending and prevent corrosion getting into the crimp.

I have evolved my crimping technique based on experience (failure) and practices for different industries. If you are going to do more than a few crimps, invest in a knock off decent crimper (about $50-80) that has different size dies, get decent alloy crimps that have nylon insulation (vinyl insulated crimps do not crimp well, nor handle heat and usually fall off), and consider using some fusible heat shrink to provide some strain relief. After you crimp, you can solder the tip of the exposed wire to prevent any corrosion getting into the crimp. On high voltage (120 and above) I crimp, solder the wire tip and use fusible shrink tubing over the crimp. Soldering is controversial in this application. Also when making bare wire terminal connections with stranded wire, do not solder the wire, as the solder will cold flow and the connection will loosen.
 
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