Copper ground cable

Date 02-17-2014 21:05

If the "Ground cable" is overheating, you better find where the short circuit is in the machine.

Now if you are talking about the work lead overheating, I would ask the question, "Why is the cable over heating? Is the cable undersized or are the connections loose or heavily oxidized?"

Usually, once the work lead is over heated, the connections become oxidized, making the heating problem more severe. It is like a snowball rolling downhill. The thing is, you can't make it worse than it is once the insulation has melted and burned off. The upside is the insulation will not have to be removed when it is sold to the scrape dealer.

Al

By 46.00

Date 02-17-2014 21:28

The problem is the electrical resistivity of copper cable increases with the increase in temperature, this will produce more heat and so on and so forth. After several overheating episode, the copper has lost some of it's cross sectional area and so is less efficient and the conductivity drops but the resistance increases.

The easiest way is for you to answer your own question. Get a new section of copper ground cable of a given length, say 20/30 feet and measure the resistivity with your bog standard electrical multi meter or a dedicated Ohms meter. Then get 20 feet of your burned out cable and measure the resistivity. The difference in the two figures will show the effect and the loss of efficiency. Bear in mind, this would ideally need to be done whilst welding was taking place using these ground cables.

By marktski (**)

Date 02-17-2014 21:44

Thanks guys, that's pretty much what I had figured. We'll cut of 8-10 inches and re-lug it.
We changed the grd clamp Friday morning. We're pulse mig welding around 250 with a Miller
350P.

By 357max

Date 02-18-2014 16:17

Ohms reading should not be taken with "power" through the cable. The ohms meter uses its own voltage to conduct current through a conductor. Power on would warrant a new meter.

By marktski (**)

Date 02-18-2014 16:31

We cut the lug end back a foot and re-lugged it. We also put on a better clamp.
We'll check it later to see if it still heats up.

By Blaster (***)

Date 02-18-2014 20:47

Since I started loading lugs and connectors up with Ilsco De Ox goo (http://www.ilsco.com/e2wShoppingCatalog.aspx?parentId=3100012691&parentLink=2100001183:3100012192:3100012193:3100012691)I have found welding leads tend to last a long time.... well other than the cuts and smashes from iron getting dropped on them.

An electrician turned me on to the stuff some years ago.

By Stringer (***)

Date 02-19-2014 00:18

Clean and tight grounds are like safety - lots of attention and sweat required. Double for GMAW.

By Think Positive (*)

Date 02-19-2014 11:55

I was taught to solder the leads into the socket before crimping them to optimize the electrical conductivity. Just some food for thought for those who do not use this practice.

By Tommyjoking (****)

Date 02-20-2014 02:30

If you are blackening your conductors they do not meet your amperage requirements. Smoking as they like to call it is like using 1/0 lead on pipeline applications...barely adequate. IF you have a hot spot in your process your conductors will show so as blackened copper. Step up two sizes and carry on if you wish not to study the actual current loads.

By Think Positive (*)

Date 02-20-2014 16:05

Point well taken, and thank you for posting a great reminder.

If the original equipment was properly installed the cable size should be sufficient, but it does pay to consult any available resources if the current capacity is unknown.

I have not seen many people solder the connections, but then too, I have not looked at many installs of lugs. I do remember what I was taught though. Please excuse me if I seem like a perfectionist.