Welding Polarity Explained: DCEP, DCEN, and AC
DCEP (electrode positive) gives deeper penetration and is used for most stick rods and MIG. DCEN (electrode negative) gives shallower penetration and is used for TIG on steel and self-shielded flux-core. AC alternates between both and is required for TIG on aluminum.
Polarity controls where the heat concentrates in the arc. Getting it wrong means the rod will not strike, the arc will be unstable, or the weld will have no penetration. Every welding consumable has a required polarity. Here is what each one means and when you use it.
DCEP (DC Electrode Positive)
Also called reverse polarity or DC+. The electrode is positive and the workpiece is negative. Electrons flow from the workpiece to the electrode, which concentrates about two-thirds of the arc heat at the electrode tip.
Despite more heat at the electrode, DCEP produces deeper penetration in consumable electrode processes (stick, MIG, flux-core). The higher electrode melting rate, more forceful metal transfer across the arc, and plasma jet dynamics directed toward the work all contribute to deeper fusion into the base metal.
Used by: E6010, E7018, ER70S-6 (MIG), E71T-1 (gas-shielded flux-core), all aluminum wire. This is the most common polarity in welding.
DCEN (DC Electrode Negative)
Also called straight polarity or DC-. The electrode is negative and the workpiece is positive. Electrons flow from the electrode to the workpiece, concentrating about two-thirds of the arc heat at the workpiece.
For consumable electrode processes (stick, MIG, flux-core), DCEN produces shallower penetration despite more heat at the work. The lower electrode melting rate and less forceful droplet transfer result in a wider, softer weld profile. However, for TIG welding (non-consumable electrode), DCEN actually produces deeper penetration because the concentrated heat at the workpiece is not offset by metal transfer dynamics.
Used by: E6012, E71T-11 (self-shielded flux-core), E71T-GS, TIG welding (GTAW). DCEN is the standard TIG polarity.
AC (Alternating Current)
The polarity completes 60 full cycles per second, reversing polarity 120 times per second (in North America). The arc goes out and re-establishes every half cycle. This means AC has characteristics of both DCEP and DCEN.
Advantage: AC eliminates arc blow, which is the magnetic deflection of the arc that can occur with DC on magnetized steel. AC also runs on simpler, less expensive machines.
Disadvantage: The arc is less stable than DC because it extinguishes at every zero crossing. Some rods are designed to re-ignite easily on AC (E6011, E6013, E7016).
Used by: E6011, E6012, E6013, E7014, E7016, E308L-16, E309L-16. TIG welding on aluminum uses AC to break the oxide layer.
Quick Polarity Reference
DCEP: E6010, E7018, all MIG wire, gas-shielded flux-core (E71T-1) DCEN: E6012, self-shielded flux-core (E71T-11, E71T-GS), TIG on steel AC: E6011, E6012, E6013, E7014, E7016, stainless rods (-16 suffix), TIG on aluminum AC or DCEP: E7018 (needs high-OCV AC machine) Any polarity: E6013 (runs on anything)
When a rod lists multiple polarities, start with DCEP for best results unless you have a specific reason to use AC.
What It Costs
AC-only buzz boxes cost $150-250 and run E6011, E6013, E7014, and E7018 on AC. DC inverter welders cost $300-600 and unlock E6010, better E7018 performance, and TIG capability. AC/DC machines cost $400-800 and cover everything.
Welding Polarity Explained: Common Questions
What is DCEP in welding?
DCEP stands for Direct Current Electrode Positive, also called reverse polarity or DC+. The electrode (rod or wire) is connected to the positive terminal and the workpiece to the negative terminal. Current flows from the workpiece into the electrode. In consumable electrode processes like stick and MIG, DCEP produces deeper penetration into the base metal because of the more forceful metal transfer across the arc. DCEP is the most common polarity in welding. E6010, E7018, all MIG wire, and gas-shielded flux-core wire all run on DCEP. E7018 runs best on DCEP. See the full E7018 specifications for amperage settings. E6010 specifications, a DCEP-only rod used for pipe root passes.
When should I use AC for stick welding?
Use AC polarity for stick welding when running rods designed for AC (E6011, E6013, E7014, E7016), when your machine is AC-only, or when you need to eliminate arc blow. Arc blow is a magnetic deflection of the arc that occurs with DC current on magnetized steel or when welding near the edges of a workpiece. Switching to AC eliminates arc blow because the polarity reverses 120 times per second. E6011 is the most popular AC rod for general-purpose work. E7018 can run on AC but requires a machine with at least 70-80V open circuit voltage for reliable arc starts. E6011 specifications, the most versatile AC stick electrode.
Does polarity affect penetration?
Yes, polarity directly affects weld penetration in consumable electrode processes (stick, MIG, flux-core). DCEP (electrode positive) produces the deepest penetration because of more forceful metal transfer and plasma jet dynamics directed toward the workpiece. DCEN (electrode negative) produces the shallowest penetration with a wider, flatter bead profile. AC falls between the two because it alternates between DCEP and DCEN characteristics 120 times per second. For TIG welding (non-consumable electrode), the relationship reverses: DCEN gives deeper penetration because heat concentrates at the workpiece without the metal transfer dynamics that affect consumable processes.
Reference data only. Verify all settings against manufacturer documentation and the applicable welding code before use. Amperage ranges are starting points that vary by position, fit-up, and material. Welding involves serious injury risks including burns, electric shock, fume exposure, and fire. This site does not replace proper training, certification, or employer safety procedures. See full terms of use.
Classification system defined by AWS A5.1/A5.1M, Miller Electric polarity reference.