Coil Voltage vs Line Voltage: What's the Difference on a Contactor?
By J. Houston | Kent Electrical Supply | Updated 04/2026
Coil voltage (also called control voltage) is the low-voltage signal that energises a contactor's electromagnetic coil, measured at the A1 and A2 terminals. Line voltage is the main power supply running through the L1, L2, and L3 power poles. These two voltages are independent — a 480V line voltage system is almost always controlled by a 24V or 120V coil, not a 480V one.
What Is Coil Voltage on a Contactor?
Coil voltage is the voltage applied to a contactor's electromagnetic coil to energise it and close the main contacts. It is measured at the A1 and A2 terminals — located on the top of the contactor, separate from the main power poles. Common coil voltages are 24V AC, 120V AC, and 240V AC.
When your control circuit sends voltage across A1 and A2, it creates a magnetic field that pulls the contactor's armature closed, connecting the load. Remove that voltage, and the spring-loaded contacts open. The coil is the switching mechanism — it is not carrying load current, and its voltage rating has nothing to do with the power passing through the power poles.
What Is Line Voltage on a Contactor?
Line voltage is the main power supply voltage flowing through a contactor's power poles — the L1, L2, and L3 input terminals on a 3-pole contactor — and out through the T1, T2, and T3 load terminals. Common line voltages in North American industrial applications are 230/240V and 460/480V.
Line voltage is determined entirely by your power supply and the load being controlled. It is independent of the control circuit. A motor drawing power at 480V line voltage can be switched on and off by a contactor with a 24V coil — the two circuits are electrically separate inside the device.
How to Tell Coil Voltage and Line Voltage Apart
When examining a contactor in the field or ordering a replacement, these are the reference points:
- Coil voltage is measured at the A1 and A2 terminals — typically on the top face of the contactor
- Line voltage is measured at the L1, L2, and L3 terminals — the main power input
- The contactor nameplate lists both ratings separately; coil voltage is labelled "Uc" or "coil voltage" on most manufacturers' nameplates
- Coil voltage is also encoded in the part number suffix on most major brands — check the manufacturer's part number decoder before ordering
- If your line voltage is 480V, your coil voltage is almost certainly not 480V — see the section below
Coil Voltage Reference Chart by Contactor Series
The table below covers common coil voltage options across the five most widely specified contactor families. Each manufacturer offers additional voltages — confirm your specific model using the linked category pages or the manufacturer's datasheet.
| Manufacturer | Series | Common Coil Voltages | Coil Terminals |
| Schneider Electric | LC1D | 24V AC, 120V AC, 240V AC | A1 / A2 |
| Eaton | XTCE | 24V AC, 110V AC, 240V AC | A1 / A2 |
| Siemens | 3RT1 | 24V DC, 120V AC, 230V AC | A1 / A2 |
| GE | CL | 24V, 120V, 208–240V | A1 / A2 |
| Lovato | BF | 24V, 110V, 230V | A1 / A2 |
For Schneider LC1D contactors, the coil voltage is encoded at the end of the part number — "B7" denotes 24V AC and "F7" denotes 110V AC. Eaton XTCE contactors follow a similar suffix structure. Full coil voltage specifications for each series are available on the respective brand pages:
Is 480V Coil Voltage Possible?
A 480V coil voltage is extremely rare and is almost never the correct choice for a replacement contactor. In nearly all cases, if the line voltage in your system is 480V, the coil (control) voltage will be 24V or 120V — not 480V. Ordering a 480V coil contactor when your control circuit runs at 24V or 120V is one of the most common and costly ordering mistakes in industrial electrical procurement.
The reason is straightforward: most industrial control circuits are intentionally designed at lower voltages to reduce shock risk when technicians work on control wiring. Running a control circuit at 480V provides no functional advantage and creates a significant safety hazard. Virtually all 480V-rated systems use a step-down control transformer to reduce the control voltage to 120V or 24V before it reaches the contactor coil circuit. If you believe your coil voltage is 480V, verify the control transformer output voltage before ordering.
What Happens If You Use the Wrong Coil Voltage?
Connecting an incorrect coil voltage will prevent the contactor from operating correctly and can cause permanent damage. A coil voltage that is too low will prevent the contactor from energising — the magnetic field won't be strong enough to close the contacts. A coil voltage that is too high — for example, applying 480V across a 120V coil — will immediately burn out the coil winding. In either case, the contactor becomes non-functional and the cost is a full replacement. Always verify the coil voltage from the nameplate or part number before installation.
Frequently Asked Questions
Q1: What is coil voltage on a contactor?
Coil voltage, also called control voltage, is the voltage applied to a contactor's electromagnetic coil to energise it and close the main contacts. It is measured at the A1 and A2 terminals on the contactor — separate from the main power poles. Common coil voltages are 24V AC, 120V AC, and 240V AC. The coil voltage is specified on the contactor's nameplate and in the manufacturer's datasheet.
Q2: What is line voltage on a contactor?
Line voltage is the main power supply voltage that flows through a contactor's power poles — the L1, L2, and L3 input terminals on a 3-pole contactor — and out through the T1, T2, and T3 load terminals. Common line voltages in industrial applications are 230/240V and 460/480V. Line voltage is independent of the coil voltage and is determined by your power supply, not your control circuit.
Q3: How do I find the coil voltage for my contactor?
Check the contactor's nameplate label, which is printed on the body of the unit and lists the coil voltage separately from the line voltage rating. You can also look up the part number on the manufacturer's product page — Schneider, Eaton, Siemens, GE, and Lovato all include coil voltage in their part number structures. For Schneider LC1D contactors, the last characters of the part number indicate the coil voltage.
Q4: Can the coil voltage and line voltage be the same?
In most industrial applications, the coil voltage and line voltage are different. While a 480V coil contactor technically exists, it is extremely rare. In the vast majority of 480V systems, the control circuit operates at 24V or 120V, meaning the coil voltage is much lower than the line voltage. Confusing the two when ordering a replacement contactor is one of the most common purchasing mistakes in industrial electrical procurement.
Q5: Where are the A1 and A2 terminals on a contactor?
The A1 and A2 terminals are the coil connection points on a contactor, typically located on the top face of the unit above the main power terminals. A1 is the positive or line side of the control circuit, and A2 is the neutral or common return. To energise the contactor, your control voltage must be applied across these two terminals. They are labelled A1 and A2 consistently across all major manufacturers including Schneider, Eaton, and Siemens.