Contactor data & coil checks
Ratings, coil resistance values, inrush/sealed VA, terminal layouts, and brand cross-references for the definite-purpose, IEC, and NEMA contactors found on single-phase and three-phase compressors. Resistance values are typical field measurements (±15%) — use them as an open/short sanity check, and always confirm against the coil label.
Contactor troubleshooting wizardC230A (2-pole 30 A)Definite purpose
Packard · 2-pole · 2 HP @ 115 V · 5 HP @ 230 V
780 series (2-pole 40 A)Definite purpose
Mars / JARD · 2-pole (3-pole in 781/783 series) · 3 HP @ 115 V · 7.5 HP @ 230 V
C25BNB230 (2-pole 30 A)Definite purpose
Eaton / Cutler-Hammer · 2-pole (C25 family spans 15–360 A, 1–4 poles) · 2 HP @ 115 V · 5 HP @ 230 V
42CF35AJ (3-pole 60 A FLA)Definite purpose
Siemens / Furnas · 3-pole · ≈ 10 HP @ 230 V · 20 HP @ 460 V
DP30C2P-1 (2-pole 30 A)Definite purpose
ABB · 2-pole (family 20–90 A) · 2 HP @ 115 V · 5 HP @ 230 V
8910DPA32 (2-pole 30 A)Definite purpose
Square D (Schneider) · 2-pole (8910 DP family 20–90 A; Type S for NEMA) · 2 HP @ 115 V · 5 HP @ 230 V
LC1D09 (TeSys D, 9 A)IEC
Schneider / Telemecanique · 3-pole (+1NO aux built in on most SKUs) · ≈ 2 HP @ 230 V · 5 HP @ 460 V · 7.5 HP @ 575 V
LC1D18 (TeSys D, 18 A)IEC
Schneider / Telemecanique · 3-pole · ≈ 5 HP @ 230 V · 10 HP @ 460 V · 15 HP @ 575 V
LC1D32 (TeSys D, 32 A)IEC
Schneider / Telemecanique · 3-pole · ≈ 10 HP @ 230 V · 20–25 HP @ 460 V · 30 HP @ 575 V
LC1D65 (TeSys D, 65 A)IEC
Schneider / Telemecanique · 3-pole · ≈ 20 HP @ 230 V · 40–50 HP @ 460 V · 60 HP @ 575 V
LC1D95 (TeSys D, 95 A)IEC
Schneider / Telemecanique · 3-pole · ≈ 30 HP @ 230 V · 60–75 HP @ 460 V · 75 HP @ 575 V
AF09-30-10 (9 A, wide-range coil)IEC
ABB · 3-pole + 1 NO aux · ≈ 2 HP @ 230 V · 5 HP @ 460 V
3RT2024 (size S0, 12 A)IEC
Siemens (SIRIUS) · 3-pole (+1 NO aux on most SKUs) · ≈ 3 HP @ 230 V · 7.5 HP @ 460 V
3RT2026 (size S0, 25 A)IEC
Siemens (SIRIUS) · 3-pole · ≈ 7.5 HP @ 230 V · 15 HP @ 460 V
100-C09 (9 A)IEC
Allen-Bradley (Rockwell) · 3-pole (+1 NO or NC aux depending on SKU) · ≈ 2 HP @ 230 V · 5 HP @ 460 V
XTCE018C (18 A, frame C)IEC
Eaton / Cutler-Hammer · 3-pole (+1 NO aux common) · ≈ 5 HP @ 230 V · 10 HP @ 460 V
8502 Type S (NEMA Size 1, 27 A)NEMA
Square D (Schneider) · 3-pole · 7.5 HP @ 230 V · 10 HP @ 460/575 V
509 Series (NEMA Size 1, 27 A)NEMA
Allen-Bradley (Rockwell) · 3-pole · 7.5 HP @ 230 V · 10 HP @ 460/575 V
AN16 / Freedom NEMA (Size 1, 27 A)NEMA
Eaton / Cutler-Hammer · 3-pole · 7.5 HP @ 230 V · 10 HP @ 460/575 V
Class 14 / ESP200 (NEMA Size 1, 27 A)NEMA
Siemens / Furnas · 3-pole · 7.5 HP @ 230 V · 10 HP @ 460/575 V
CR306 (NEMA Size 1, 27 A)NEMA
GE / ABB (300-Line) · 3-pole · 7.5 HP @ 230 V · 10 HP @ 460/575 V
CWB9 (3-pole 9 A)IEC
WEG · 3-pole (4-pole available) · 3 HP @ 230 V · 5 HP @ 460 V
CWB18 (3-pole 18 A)IEC
WEG · 3-pole (4-pole available) · 5 HP @ 230 V · 10 HP @ 460 V
CWB40 (3-pole 40 A)IEC
WEG · 3-pole · 10 HP @ 230 V · 25 HP @ 460 V
CWB95 (3-pole 95 A)IEC
WEG · 3-pole · 30 HP @ 230 V · 60 HP @ 460 V
Coil resistance sanity table
Typical DC resistance measured across A1–A2 at room temperature (±15% or more). Use as a ballpark only — the published spec is inrush/sealed VA.
| Coil voltage | Small frame | Mid frame | Reading meaning |
|---|---|---|---|
| 24 VAC | ≈ 8–16 Ω | ≈ 4–9 Ω | OL = open coil. 0–2 Ω = shorted turns (often from a cooked transformer). |
| 110–120 VAC | ≈ 150–450 Ω | ≈ 60–180 Ω | Readings 2× high usually mean heat damage and a coil near end of life. |
| 208–240 VAC | ≈ 600–1,500 Ω | ≈ 250–700 Ω | Measure coil-to-frame too: must be >1 MΩ or the coil is going to ground. |
| 380–480 VAC | ≈ 1.5–4 kΩ | ≈ 700–2 kΩ | High-voltage coils fail open after repeated undervoltage chatter. |
Meter check ≠ health check
A coil can pass the ohms test and still chatter or run hot from shorted turns. The live test is sealed current: measure coil amps energized and compare to sealed VA ÷ coil volts. Electronic coils (ABB AF, some Eaton XT) read misleading ohms — voltage-test those instead.
NEMA size ratings (all brands)
| Size | Amps | 3Φ 230V | 3Φ 460V | 3Φ 575V | 1Φ 115V | 1Φ 230V | Typical use |
|---|---|---|---|---|---|---|---|
| 00 | 9 A | 1.5 HP | 2 HP | 2 HP | ⅓ HP | 1 HP | Small fans, fractional pumps |
| 0 | 18 A | 3 HP | 5 HP | 5 HP | 1 HP | 2 HP | 2–5 HP recips, condenser fans |
| 1 | 27 A | 7.5 HP | 10 HP | 10 HP | 2 HP | 3 HP | 5–10 HP recips — the classic shop size |
| 2 | 45 A | 15 HP | 25 HP | 25 HP | 3 HP | 7.5 HP | 15–25 HP screws and two-stage recips |
| 3 | 90 A | 30 HP | 50 HP | 50 HP | — | 15 HP | 30–50 HP rotary screws |
| 4 | 135 A | 50 HP | 100 HP | 100 HP | — | — | 75–100 HP screws |
| 5 | 270 A | 100 HP | 200 HP | 200 HP | — | — | 150–200 HP screws, wye-delta pairs |
| 6 | 540 A | 200 HP | 400 HP | 400 HP | — | — | Large industrial plants |
Schneider TeSys coil voltage codes
The last characters of an LC1D part number encode the coil — LC1D18G7 is a 120 VAC coil. Wrong code = coil burns out or never pulls in.
B724 VAC 50/60 Hz
D742 VAC
E748 VAC
F7110 VAC 50 Hz
FE7115 VAC 60 Hz
G7120 VAC 60 Hz
M7220 VAC 50 Hz
P7230 VAC 50/60 Hz
U7240 VAC 60 Hz
Q7380 VAC 50 Hz
V7400 VAC 50/60 Hz
N7415 VAC
R7440 VAC
BD24 VDC
MD220 VDC
Frequently asked
How do I test a contactor coil with a multimeter?
Power off and locked out. Measure across A1–A2: a good coil reads its typical DC resistance (see the coil sanity table), an open coil reads OL, and shorted turns read far below normal. Also measure coil-to-frame — anything under 1 MΩ means the coil is leaking to ground.
Why does my contactor chatter?
Low coil voltage — under about 85% of rated — is the cause 9 times out of 10. Measure voltage at A1–A2 while the circuit is calling for run. Long control runs, an undersized transformer, or a bad pilot contact all drop voltage under load.
What is the difference between NEMA and IEC contactors?
NEMA sizes (00–8) are deliberately oversized and rebuildable; IEC ratings (AC-3, AC-1) size the device tightly to the exact duty. A NEMA Size 1 is roughly a 30 A IEC device with more fault headroom. IEC is compact and cheap; NEMA survives abuse.
Can I replace a definite-purpose contactor with an IEC contactor?
Yes, if the IEC unit's AC-3 rating meets or exceeds the motor FLA and the coil voltage matches. IEC contactors are usually a durability upgrade over 2-pole DP frames on compressors.
What do the letters at the end of a Schneider LC1D part number mean?
The last two characters are the coil voltage code — G7 = 120 VAC 60 Hz, B7 = 24 VAC, P7 = 230 VAC. Order the wrong code and the coil either won't pull in or burns out. See the coil-code table on this page.