Most topside stick runs DCEP, but underwater we usually go DCEN — last week at 90 ft I burned 3.2 mm E7014 wet rods that way for a tighter bead, less arc blow, and to manage OCV exposure. Trivia for the safety-minded: what’s the original reasoning behind DCEN becoming the standard underwater — diver protection, hydrogen control, bead profile, or something else?
But > exposure. Trivia for the safety-minded: what’s the original reasoning behind DCEN becoming the standard underwater — originally to keep the stinger as the cathode so the hand-held end isn’t the anode spitting chlorine/oxygen in seawater, and to keep heat off the flux so the bubble holds. DCEN also throws more heat into the work, which is why your 3.2 mm 7014 at 90 ft wets in tighter with less arc blow; the OCV hazard isn’t about polarity — it’s the topside knife switch/isolation that matters.
Original push was diver protection — keep the stinger as the cathode so any insulation weep has less bite and the highest potential sits at the work, not in your hands. The tighter bead and less arc blow you saw at 90 ft are side benefits; if a rod wants DCEP topside, flip to DCEN underwater and bump amps about 10–15% to hold penetration. @alex_smith91 had it right with “keep the stinger as the cathode,” especially for managing OCV exposure.
Started as a rod-survivability call: early wet 6013/7014 coatings cooked on DCEP and shed the waterproof binder, so DCEN kept the flux intact and pushed heat into the plate. At about 90 ft the tighter bubble makes it worse, which is why you got that tidy bead plus the “OCV exposure” perk. @daniel_flores07 you seen DCEP behave any better with the newer polymer-bonded wet rods, or still too gassy?
I’ve always heard DCEN stuck partly for chemistry as much as shock risk: put the plate on the positive side and you shove chlorine/oxygen evolution and corrosion away from your hands, instead of brewing ‘bleach’ right at the holder. Flip to DCEP in a test tank and you’ll smell it and watch early wet 7014 coatings soften faster — NAVSEA backs DCEN in the Diving Manual, ch. 11: https://www.navsea.navy.mil/Portals/103/Documents/SUPSALV/Diving/divepubs/SS521-AG-PRO-010/Ch11.pdf. Your nose will tell you faster than a voltmeter.
Another piece of the puzzle: long umbilicals plus old droopers/rectifiers made DCEP spikeier at the tip, so DCEN pushed current into the work and kept the gas “bubble” tight instead of a boil over your lens. Try a quick A/B on scrap at 30–40 ft and you’ll see it; @saltysparks, I’m curious if the newer inverters have narrowed that gap, but the habit stuck.
Mostly a heat-balance call in seawater: DCEN makes the plate the anode, so about 2/3 of the arc heat goes into the work and you still get fusion in that ‘90 ft’ quench while the tip stays cooler. @benbake the chemistry helps, but that fusion margin with 3.2 mm rods is what made it standard; arc-blow and diver tingle were secondary. Ever try matching your bead on DCEP down there without the tip boiling?