The overload relay's 95-96 contact can sit on either side of the contactor coil. NEMA practice wires it on the return side between coil A2 and L2. The hot-side alternative places it between L1 and the STOP button. Both stop the motor on an overload trip, and our simulators accept either placement.
Open a motor control panel built in Ohio in 2005 and trace the overload relay contacts. Open an identical-function panel from a different builder that same year and trace them again. In normal operation the circuits do the same thing, and the overload protection works the same way. But the 95-96 contact is wired into a different part of the control circuit, and both installations are accepted practice.
This is not a wiring error, a regional shortcut, or a sign that someone improvised. It is the result of two common practices, each defensible, answering the same question: where should the overload relay's normally-closed contact interrupt the coil circuit?
The Contact in Question
Every thermal overload relay has a set of normally-closed auxiliary contacts designated 95-96 per IEC terminal marking conventions. These contacts sit in series with the contactor coil. When the relay's heaters detect sustained overcurrent and the bimetallic mechanism trips, the 95-96 contact opens, the coil circuit breaks, and the contactor drops out. The motor stops.
The contact is bidirectional. Terminal 95 can be the input or the output. What matters is that it appears somewhere in the series path between the hot conductor and the coil return. The question is where in that path.
Two answers have become standardized.
Instrument: Topology Comparison
Return-Side Placement: The NEMA Convention
In the North American tradition governed by NEMA standards, the 95-96 contact is placed on the return side of the coil, between the coil's A2 terminal and the return conductor (L2 in a line-voltage circuit, X2 in a transformer-fed circuit).
The control circuit path reads:
L1 → STOP (NC) → START (NO) → Coil A1 ... Coil A2 → OL 95 → OL 96 → L2
This is how NEMA-rated motor starters ship from the factory. Allen-Bradley 509-series, Eaton Freedom/AN16, Square D 8536, and Siemens Class 14 all leave the production line with two internal jumper wires already installed: A2 to 95 and 96 to L2. The electrician in the field never touches these connections. The overload protection is pre-wired as part of the assembly, and the field wiring is limited to the hot-side control chain (STOP, START, seal-in) and the power terminations. For a walkthrough of every factory jumper inside a NEMA starter, see What's already wired inside your motor starter.
This convention exists for practical reasons, not arbitrary ones.
Factory prewiring removes a field step. If the OL contact must be field-wired, it can be left out. If the 95-96 contact is part of the coil's series path and left open, the starter will not pull in. If it is left out instead, with the coil wired straight to the return, or jumpered to stop nuisance trips, the starter pulls in and the motor runs with no overload-trip shutdown. Factory prewiring removes the field step where that can happen.
Troubleshooting is simpler on the return side. The OL contact sits next to the coil in its return path, so a trip removes the return at one known point. The trade-off is the bypass path described in the hot-side section below: a fault on the return conductor downstream of the OL can route current around the open contact.
NFPA 79 (Industrial Machinery) permits this convention under its 8.3.1 Exception: the OL contact may sit in the grounded return conductor of a grounded control circuit, provided the conductors between that contact and the coil stay inside the control enclosure. It is what most North American trade programs, apprenticeship JATCs, and electrical training curricula teach as the standard configuration. For the complete field wiring procedure with this convention, see How to wire a motor starter.
Hot-Side Placement
Hot-side placement takes the opposite position. The 95-96 contact sits on the hot side of the coil circuit, between the hot conductor and the first control device (typically the STOP button). Our simulators accept this placement alongside the return-side default.
The control circuit path reads:
L1 → OL 95 → OL 96 → STOP (NC) → START (NO) → Coil A1 ... Coil A2 → L2
The OL contact is now the first device the current encounters after leaving the hot bus. The engineering rationale is different from NEMA's, and it is equally sound.
The OL contact interrupts the ungrounded conductor. In a ground fault scenario where the return conductor accidentally contacts the grounded enclosure, a return-side OL contact might not cleanly de-energize the coil: the fault provides an alternate return path that bypasses the open contact. With the OL on the hot side, a trip opens the circuit upstream of everything else. No current reaches the coil, the STOP button, or the START button, regardless of what faults exist downstream. NEC 430.74 sets the requirement for grounded control circuits: a ground fault in the control circuit remote from the controller must not start the motor or bypass manually operated or automatic shutdown devices. This article does not rule on whether a given return-side layout meets that requirement. The hot-side layout avoids the bypass path, because every control path from L1 passes the OL contact.
Side by Side
| NEMA (Return-Side) | Hot-Side | |
|---|---|---|
| OL position in circuit | After coil, before return | Before STOP, after hot |
| Factory prewired? | Yes: NEMA starters ship this way | No: requires field wiring |
| Ground fault behavior | A fault downstream of the OL can bypass the open contact | Every control path from L1 passes the OL contact |
| Primary standard | NFPA 79 | No single rule cited here |
| Accepted in our simulators | Yes | Yes |
Both Are Accepted
There is no wrong answer for normal operation. In both conventions, the motor stops when the overload trips. The 95-96 contact opens, the coil loses excitation, the contactor drops, and the motor is disconnected from power. In normal operation the protection function is the same. Ground-fault behavior differs, as covered above.
What differs is the failure mode under fault conditions and the practical logistics of installation. NEMA's approach optimizes for field reliability: fewer wires to forget, fewer ways to install the starter without protection. The hot-side approach favors fault isolation: the contact position provides cleaner de-energization when something else in the circuit has already gone wrong.
NEC Article 430 requires overload protection but does not fix the contact position within the control circuit. NFPA 79 Section 8.3.1 Exception permits the OL contact in the grounded return conductor of a grounded control circuit, when the conductors between it and the coil stay inside the control enclosure. Our simulators accept the OL contact on either side of the coil; NEMA and US practice puts it on the return side. The choice is governed by the applicable machinery standard, the plant's engineering specifications, or the Authority Having Jurisdiction.
What to Look For in the Field
When you open a panel and need to identify the convention in use, trace the 95-96 wires:
-
If terminal
95or96connects to a coil terminal (typicallyA2), you are looking at return-side placement: the NEMA convention. The OL return path runs from the coil through the relay and back to the return bus. -
If terminal
95or96connects to the hot conductor or the first control device (typically the STOP button's input terminal), you are looking at hot-side placement. The OL sits upstream of the entire control chain.
Check the schematic on the inside of the panel door. On a ladder diagram, the OL contact symbol (two bars with a diagonal slash) will appear either between the coil and the return rail (NEMA) or between the hot rail and the first control device (hot side). The position on the schematic matches the position in the field wiring.
If you maintain equipment from multiple OEMs or work in a plant that has been expanded over decades, expect to find both conventions in the same facility. This is normal. Neither needs to be "corrected" to match the other.
Reading is one thing; wiring it yourself is another. Open the interactive trainer and build this circuit from scratch.
The trainer starts with NEMA return-side placement. Wire it, then move the OL contact to the hot side and see that both conventions stop the motor the same way on an overload trip. Free, no account. →Frequently asked questions
Where does the overload relay's 95-96 contact go in a NEMA motor starter?
On the return side of the coil, between terminal A2 and the L2 return conductor. NEMA-rated starters from Allen-Bradley, Eaton, Square D, and Siemens ship from the factory with two internal jumpers (A2 to 95 and 96 to L2), so the field electrician never wires the OL contact at all. The convention is consistent with common NEMA practice and standard manufacturer practice across North American OEMs.
Where does the overload relay's 95-96 contact go in a hot-side starter?
On the hot side of the control circuit, between L1 and the STOP button. This places the OL upstream of the entire control chain, so an overload trip de-energizes everything downstream (coil, pushbuttons, and seal-in). Nothing is factory-jumpered on this layout; the electrician lands every control conductor.
Is NEMA or hot-side overload placement safer?
Neither. In normal operation the motor stops the same way in both: the 95-96 contact opens, the coil drops, and the contactor disconnects the motor. NEMA's return-side placement reduces field errors because the OL contact is pre-wired at the factory. Hot-side placement gives cleaner fault isolation if a ground fault lands on the return conductor downstream of the OL. NEC Article 430 requires overload protection but does not dictate the contact's position.
How do you tell which convention a panel uses?
Trace the 95-96 wires. If 95 or 96 lands on the coil's A2 terminal, the panel is wired return-side (NEMA). If 95 or 96 lands on the hot conductor or the input of the STOP button, the panel is wired hot-side (IEC). The schematic on the inside of the panel door shows the same position: between coil and return rail for NEMA, between hot rail and first control device for IEC.
Can both conventions exist in the same facility?
Yes, and they routinely do. A North American plant that has been expanded over decades will have NEMA starters from domestic OEMs alongside starters wired hot-side by other builders. Neither needs to be "corrected" to match the other. Maintain each piece of equipment to the convention it was built with.