Welding Polarity Explained: DCEP, DCEN, and AC

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. About two-thirds of the arc heat concentrates at the electrode tip.

This produces deeper penetration into the base metal because the electrons flow from the work toward the electrode, bombarding the workpiece surface.

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. About two-thirds of the arc heat concentrates at the workpiece.

Counterintuitive fact: even though more heat goes to the work, DCEN actually produces shallower penetration on most processes. The reason is that electron emission from the electrode creates a wider, softer arc cone.

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 switches between positive and negative 60 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, 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.

Classification system defined by .