What it is
The Molex 391002204 is the 4-circuit member of the Eurostyle 39100 barrier-terminal family, rated 40A per circuit at 600V. The enclosed barrier houses two rows of four positions at 0.472" (12.00mm) pitch, accepting 8-20 AWG conductors via top-entry zinc-plated steel screws against a closed bottom — the closed bottom means no rear wire entry, which keeps the termination side clean in panel and chassis applications.
What the ratings mean
The 40A per circuit rating is sized for motor branch circuits and power distribution taps — the 8-20 AWG wire range supports the heavier gauges that carry that current in the field. The UL94 V-0 polyamide body (PA66, Nylon 6/6) handles the heat rise from sustained current without deforming, and the -40°C to 105°C operating window covers outdoor enclosures and industrial environments where barrier strips are typically spec'd. The 600V rating sets the application ceiling — this strip is in the standard industrial distribution band, suitable for 480V branch circuits when properly derated per the applicable standard. The enclosed barrier type prevents accidental contact with live screws in field conditions, which is the practical reason these are specified in panel builds over open-barrier alternatives.
Where it sits in the series
The 391002204 sits between two peers at different pitch steps. The 0391002502 carries 2 circuits at 0.591" (15.00mm) pitch rated 63A — a larger pitch and higher current, but half the circuit count. The 0391002012 runs the other direction: 12 circuits at 0.394" (10.00mm) pitch rated 30A — more positions in a tighter footprint at lower current. The 391002204 occupies the middle ground at 12.00mm pitch with 40A, making it the right fit when the circuit count is fixed at 4 and the wire gauge sits between the two peers' ranges.