L1, L2, L3
The manufacturer-designated line terminals. IEC-style products often show 1/L1, 3/L2 and 5/L3.
Contactor terminal guide
What Are L and T Terminals on a Contactor?
On a typical three-pole AC contactor, L marks the line or source side. T marks the load side. Common pairs are 1/L1–2/T1, 3/L2–4/T2 and 5/L3–6/T3. The exact model diagram always has the final word.
L = line sideConnect the source here unless the exact manual allows another arrangement.
T = load sideEach T terminal pairs with one main power pole.
A1/A2 = coilThese control the contactor; they are not L/T power terminals.
Open is not isolatedBackfeed or welded contacts can still leave a terminal live.
A DIN-rail contactor has separate power and control connections. Read the exact markings; do not rely on position alone. Photo: Kae, Wikimedia Commons, CC BY-SA 3.0. Cropped for layout.
Quick answer
Read the function, then the pair
L and T belong to the main power path. The coil and auxiliary contacts use different marks.
L brings the circuit to the main contacts. T carries it toward the load after those contacts close.
This is the common meaning of L and T terminals on a contactor. It does not prove whether a terminal is live. It also does not replace the model drawing, rating label or installation instructions.
T1, T2, T3
The paired load terminals. Common marks are 2/T1, 4/T2 and 6/T3.
A1 and A2
The coil terminals. Match the coil code, voltage, frequency, AC/DC type and any polarity marks.
13–14 / 21–22
Common auxiliary-contact marks: 13–14 is often normally open; 21–22 is often normally closed.
Common convention, not a universal drawing: many NEMA-style products show L1/L2/L3 and T1/T2/T3 without the leading numbers. Four-pole, normally closed, latching, DC and special-purpose contactors may differ.
| Typical mark | Usual role | Common pair or state | What to verify |
|---|---|---|---|
| 1/L1 | Line terminal for main pole 1 | Pairs with 2/T1 | Source direction, AC/DC rating and conductor data |
| 3/L2 | Line terminal for main pole 2 | Pairs with 4/T2 | Pole use and phase sequence on the drawing |
| 5/L3 | Line terminal for main pole 3 | Pairs with 6/T3 | Starter and overload-relay arrangement |
| 7/L4 | Possible fourth main pole | Often pairs with 8/T4 | Whether the pole is NO or NC and its stated duty |
| A1 / A2 | Electromagnetic or electronic coil | Energizing changes contact state | Coil voltage, AC/DC, frequency and polarity |
| 13–14 / 21–22 | Auxiliary control contacts | Often NO / NC | Contact state and AC-15 or DC-13 control rating |
Two separate circuits
How power moves from L to T
The contactor has a main power path and a control path. They interact through a moving mechanism, not through a direct electrical link.
Source
Power comes from the supply through the required upstream switching and protection.
L terminals
The source lands on the line side named by the product drawing.
Main contacts
The coil-driven mechanism changes the state of the main poles.
T terminals
The paired load side feeds the next approved device in the circuit.
Load
The path may continue through an overload relay before a motor.
Main power path
Source → protection → L → main contacts → T → load.
A contactor makes and breaks its stated utilization duty. It is not short-circuit or overload protection by itself.
Control path
Control supply → A1/A2 coil → moving mechanism.
A PLC, pushbutton or relay may command this path. Auxiliary contacts can report state or support an interlock.
A contactor is not a safety isolator. An open main contact or a coil with no voltage is not proof of a safe work condition. Use the specified disconnecting means, isolate every energy source, apply lockout/tagout and verify absence of voltage.
Read the symbols
Main poles, coil and auxiliary contacts are different parts
The three main poles carry the power circuit. The coil operates the mechanism. Auxiliary contacts have their own state and control rating.
- Do not put motor current through an auxiliary contact.
- Do not treat A1/A2 as another L/T pair.
- Do not infer terminal order from top and bottom position alone.
Diagram: Fluppe37, Wikimedia Commons, CC0 1.0.
Power state & direction
T may be live, even when the coil is off
Labels describe circuit function. They do not certify that a conductor is safe to touch.
Main poles open
On a simple single-source circuit with healthy normally open contacts, the L side is supplied and the T side is separated.
This is an operating description, not a safe-isolation test.
Main poles closed
With the correct control voltage at A1/A2, the mechanism closes the main poles. Power can then pass from each L terminal to its paired T terminal.
Backfeed or welded contacts
A drive, generator, capacitor, battery, parallel source or welded contact can leave T energized. Stored energy can also remain after switching.
Can L and T be reversed? Do not assume so. Connect source to L and load to T unless the manufacturer expressly permits reverse feed for that catalog number. A reversed unit may appear to switch yet lose a listed rating, arc-control function, protection coordination or intended touch safety.
Inside the device
The coil moves the contacts; it does not carry the load current
An energized coil creates magnetic force. The mechanism then changes the contact state. The L and T terminals belong to the main current path.
DC main poles may use magnets or arc chutes with a required direction or polarity. That is separate from coil polarity. Check both when the application is DC.
Photo: Dmitry G, Wikimedia Commons, CC BY-SA 3.0. Cropped for layout.
Pole count is not phase count
Single-phase and three-phase use different plans
Choose a contactor by its approved duty. Do not copy a three-pole motor diagram into a single-phase starter.
One contact pair
A true single-pole contactor has one main pair. It does not have L1/L2/L3 and T1/T2/T3.
Often two poles
A single-phase load may use an approved two-pole product or named poles on a multi-pole device. Follow the equipment diagram.
Usually three poles
Typical mapping is L1→T1, L2→T2 and L3→T3. Keep the designed phase sequence through the circuit.
A fourth switched path
The fourth pole may serve a stated phase or neutral duty. It is not automatically identical in every design.
Motor direction is a phase-sequence issue. Moving the same three phases from L to T does not reverse a motor. Reversing normally swaps two phases through an approved reversing starter with electrical and mechanical interlocking.
Starter exception: a bare contactor and a contactor-overload assembly may use different single-phase paths. Some electronic overload relays require current through all three sensing paths. Use the complete starter diagram.
Do not mix circuits
Read the NO/NC guideL/T versus A1/A2 and auxiliary contacts
Each terminal family has a different job and rating.
L and T terminals
These carry the switched load path. Select the device by system voltage, load current and the correct utilization category.
Common motor duty is not the same as resistive heating or lighting duty.
A1 and A2
These accept the stated control supply. A1 does not always mean live, and A2 does not always mean neutral.
Follow the coil code and any A1+/A2− mark. Some coils are polarized; others are not.
13–14 and 21–22
13–14 often marks a normally open contact. 21–22 often marks a normally closed contact.
Use only the stated AC-15 or DC-13 control rating. These contacts are not main-load poles.
Ue / IeOperational voltage and currentRead them with the stated utilization category and operating conditions.
UcCoil control voltageCheck AC/DC type, frequency, range and any electronic-coil code.
AC-1 / AC-3Utilization categoryIt links the rating to the kind of load and switching duty.
Ui / UimpInsulation dataThese support insulation coordination; they are not the load rating alone.
Wire dataApproved conductorCheck material, size, strand type, strip length, ferrule and count per clamp.
TorqueExact terminal valueUse the product instruction and a suitable controlled tool. Do not guess by screw size.
SCPDShort-circuit protectionCoordinate the contactor with the named fuse or breaker and system fault level.
File / markMarket evidenceVerify the exact certificate, listing file and conditions for the ordered model.
Six common errors
What causes confusion in a real panel
A contactor can still operate when the installation is wrong. Function alone does not prove compliance.
Using position instead of labels
Line is often at the top, but not always. Read the face marking and product diagram.
Assuming T is dead
Backfeed, stored energy or welded contacts can make the load side hazardous.
Reverse-feeding by habit
Use L for source and T for load unless written model data permits reverse feed.
Applying the wrong coil supply
A control voltage that does not match Uc can prevent pull-in or damage the coil.
Using auxiliary contacts for power
Auxiliary ratings are for control duty. They do not replace a main pole.
Expecting protection or isolation
A contactor needs coordinated protection and a proper disconnecting method.
Diagnose, do not guess
A burned contact does not prove L and T were reversed
Heat damage can have several causes: a poor termination, overload, wrong duty rating, coil problems, excessive switching, contamination or failed protection coordination.
De-energize the equipment and preserve the evidence. Follow the maker's service limits. Replace a contact kit or complete contactor only when the product and equipment instructions allow that work.
Burned contact from a star-delta starter. The photo alone does not identify line/load reversal as the cause. Photo: Asurnipal, Wikimedia Commons, CC BY-SA 4.0. Cropped for layout.
Qualified-person checklist
Open the control-panel wiring guideHow to identify and verify the terminals
This is a verification path, not a live-wiring tutorial. Apply the locally adopted rules and the complete equipment procedure.
Capture the model
Record the full catalog number, coil code, accessory codes and revision. A family photo is not enough.
Get the exact diagram
Match every printed terminal mark to the current manufacturer drawing and panel schematic.
Identify all sources
Include mains, control power, drives, generators, batteries, capacitors and possible backfeed.
Create a safe condition
De-energize, isolate, lock/tag, release stored energy and verify absence of voltage with suitable test equipment.
Trace the two paths
Separate the L-to-T main circuit from the A1/A2 coil and auxiliary-control circuits.
Check each conductor
Confirm material, size, strand type, strip length, terminal end and allowed count per clamp.
Use stated assembly data
Apply the specified driver and torque. Fit required barriers, covers and accessories.
Commission to the plan
Verify phase order, coil operation, interlocks and protection before returning the equipment to service.
Never use PPE as a substitute for de-energization. Any energized diagnostic work needs formal justification, qualified personnel, a risk assessment, suitable rated instruments and the required work practices.
Panel context
Trace the schematic, not the nearest wire
A panel may contain several contactors, overload relays, control relays and terminal blocks. Similar-looking devices can use different coil voltages or contact arrangements.
Keep the BOM, wire markers and terminal plan aligned. SENTOP supports panel builders and switchgear teams with component matching and project supply.
Control cabinet with contactors and relays. Photo: Juanitorz, Wikimedia Commons, CC BY-SA 4.0. Cropped for layout.
Standards boundary
A marking is useful only with its rated context
Check the exact model and the complete equipment. A standard's scope is not a product rating.
Contactors and motor starters
The current IEC edition covers stated low-voltage contactor and starter types up to 1,000 V AC or 1,500 V DC. Use the exact certified product data for the application.
North American product evaluation
The active UL standard covers contactors and motor starters. It notes that these devices are normally not designed to interrupt short-circuit current. Coordinated protection is part of the installation.
Electrical safe work
For covered US workplaces, de-energization, lockout/tagout and qualified verification are central rules. Testing must also check for unrelated backfeed or induced voltage.
Faster model matching
Request model supportSend these eight inputs with your RFQ
They help SENTOP match the main contacts, coil, auxiliaries and project documents.
01 ApplicationMotor, HVAC, heating, lighting, capacitor switching or another stated load.
02 Power circuitAC or DC, phase count, system voltage, load current and available fault level.
03 DutyUtilization category, switching rate, motor kW or hp and service conditions.
04 CoilUc control voltage, AC/DC type, frequency, range and required suppressor.
05 ContactsMain-pole count, NO/NC arrangement and needed auxiliary contacts.
06 ConductorsMaterial, size, strand type, terminal end and cable-entry direction.
07 Site & panelAmbient heat, altitude, enclosure, DIN rail, vibration and accessory space.
08 Project evidenceTarget market, required file or certificate, quantity, label and OEM packing.
Attach the single-line diagram, control schematic, terminal plan and BOM when possible. You can also review the SENTOP product catalogue before sending the request.
Continue your review
Related SENTOP resources
Frequently asked questions
L and T terminal FAQ
What do L1, L2 and L3 mean on a contactor?
They normally identify the three line or source terminals on a three-pole contactor. IEC-style products may show 1/L1, 3/L2 and 5/L3. Confirm the exact model drawing before wiring.
What do T1, T2 and T3 mean on a contactor?
They normally identify the paired load terminals. Common pairs are L1–T1, L2–T2 and L3–T3. They carry the switched path toward the load when the main contacts close.
What is the difference between L/T and A1/A2 terminals?
L and T are main power terminals. A1 and A2 are coil terminals that operate the mechanism. A1/A2 do not universally mean live and neutral; match the coil code and any polarity marks.
Are T terminals live when the contactor is off?
They may be. A welded contact, stored energy, a drive, generator, battery or another backfeed source can energize the T side. Never use coil state as proof of isolation. Lock out every source and verify absence of voltage.
Can line and load terminals be reversed?
Only when the exact manufacturer documentation expressly permits reverse feed. Otherwise connect the source to L and the load to T. Continued switching does not prove that a reversed installation is correctly rated or certified.
How do I identify terminals when the labels differ?
Use the full catalog number and current manufacturer drawing. Trace the main poles, coil and auxiliary contacts separately. Do not infer function from physical position, color or a similar family photo.
What do 13–14 and 21–22 mean?
On many IEC-style contactors, 13–14 is a normally open auxiliary contact and 21–22 is normally closed. Check the exact contact state and control-duty rating before using either one.
Which L and T terminals are used in a single-phase circuit?
There is no universal pair. Use a two-pole contactor or the approved poles named by the manufacturer. A starter with an electronic overload relay may need a special three-path arrangement, so follow the complete starter diagram.
Primary sources
Standards and manufacturer evidence
- IEC 60947-4-1:2023, corrected version including COR1:2026 — contactors and motor starters.
- ANSI/UL 60947-4-1, Edition 4 — North American contactor and motor-starter standard scope.
- OSHA 29 CFR 1910.333 — de-energized work, lockout/tagout and verification in covered US workplaces.
- Siemens SIRIUS 3RT contactor manual — L/T, A1/A2 and auxiliary terminal designations.
- ABB contactor catalog — terminal positions, pole variants, coil and auxiliary examples.
- Schneider Electric line/load direction FAQ — reverse-feed limits for named TeSys D products.
- Schneider Electric A1/A2 FAQ — coil terminal identification and polarity examples.
- Schneider Electric single-phase contactor FAQ — bare contactor and overload-relay path differences.
- ABB GA/GAE DC contactor catalog — main-pole polarity and permanent-magnet arc-control examples.
From marking to matched model
Send SENTOP your load, coil voltage and contact plan
We can review your drawing, sample or BOM, then match the contactor poles, coil, auxiliary contacts, certifications, labels, quantity and OEM supply needs.
