damp molds where they have been left in a tool box or storage shed over the weekend
the process can not be used in rain or drizzle
the molds "wear out" after about 50 shots, then you have to be creative by using putty to seal against leakage or old pennies to add more copper to the mix (not listed since it changes the mix and has not been tested)
once in a while, if you are not careful, you will burn through instead making a good weld (operator error)
We used to use the Caddweld system for all of our grounding grids in our substations but have gone to the mechanical type because of the above downsides.
Each mold is specific, in my cellar I have a 4/0 to 3/4" ground rod mold and a 4/0 run to a 2 AWG tap mold.
You need a mold for each different wire size or application.
The shop has a few dozen molds in stock, some have magnetic holders that hold the mold to building steel in order to cad weld a conductor to building steel.
The process is fairly simple, clean the conductors, dry the mold (and conductors if damp) with a torch, clamp the mold onto the conductors, pour in the appropriate sized 'load', close the cover, with a glove on use a striker tool to light it off.
Bright light, lots of smoke and presto you have a permanent connection if all went well.
Remove mold carefully as the weld will be red hot and the mold is also smoking hot.
I think the molds are made of graphite but I am not sure of that.
Bob Badger Construction & Maintenance Electrician Massachusetts
#91172 - 01/02/0505:50 PMRe: Exothermic Welding or Irreversible Connections, Comments?
50 shots, how hot does the thing get, is the steel melting?
Sam, there is a very thin steel insert put into the bottom of the upper chamber and the reaction gets hot enough to completely melt the steel insert. The powder is copper oxide and aluminum, I believe. It is required to get a hot enough to actually make a weld. In my opinion, if done properly, the Cadweld makes a perfect connection and nothing is better.
Because of the graphite mold getting a little oversized, I have used old pennies (the newer ones are copper plated zinc) to take the place of the steel insert. As I said before, this is not an approved method.
Used um both cadwelds a pain in the _____ The crimp works Great just the tool is very expensive. There are now premade cadeweld charges made no pennies required that are set off electricaly no flame required.