Electromechanical contactors and mini-contactors

Every time an electromechanical contactor opens or closes to control a compressor, fan or defrost circuit, it makes an arc at the contact gap. In a refrigerant- present atmosphere, that arc is a credible ignition source. A2L compliance demands that contactor housings meet the Annex JJ maximum gap dimensions, so any flame initiated inside the housing cannot propagate through the enclosure openings into the surrounding atmosphere. Meeting those dimensions requires new tooling, retesting and certification under the UL component category LZGH2/8.

Disconnect switches

Disconnectors used for circuit isolation make the same type of arc as electromechanical contactors. A disconnector operated in an area where leaked refrigerant could accumulate poses an identical ignition risk and must meet the same Annex JJ gap geometry and arc containment requirements.
Substituting a non-certified disconnector of similar current rating into an A2L system introduces an unqualified ignition source into the circuit.

Electromechanical and monitoring relays

Control relays used for sequencing, safety interlocking or demand logic share the Annex JJ requirement whenever they sit within a potential refrigerant leak zone.
Flammable gas requirements include:

• Evaluation of spark-producing components.
• Determination of arcs and hot surfaces under normal and abnormal conditions.
• FMEA demonstrating that no fault can generate an arc capable of reaching the gas’s self-ignition temperature.

Motor protection circuit breakers

Motor protection circuit breakers (MPCBs) in compressor circuits also fall within the scope of A2L compliance when they are located in the potential refrigerant leak zone.

Components that do not arc, such as transformers or sealed solid-state electronics that cannot produce sufficient arc energy under any fault condition, typically do not require A2L-specific certification.
However, exemption still requires a documented FMEA showing that no fault scenario can generate ignition-capable energy.

The ASHRAE A2L classification means lower toxicity (A), flammable (2) and low burning velocity at or below 10 cm/s (L). The table below compares the leading A2L replacements against the legacy R-410A they are displacing.

ASHRAE Standard 34 classifications.

The high LFL values — typically 10 to 19 percent volume in air compared to roughly 2 percent for propane — mean that a large concentration must accumulate before a flammable mixture forms.
The high minimum ignition energy means A2L gases need a powerful source to ignite. An electrical arc from an electromechanical contactor or switch supplies more than enough energy, which is why switching components are the primary focus of A2L compliance.

ASHRAE Standard 34 classifications.

The high LFL values — typically 10 to 19 percent volume in air compared to roughly 2 percent for propane — mean that a large concentration must accumulate before a flammable mixture forms.
The high minimum ignition energy means A2L gases need a powerful source to ignite. An electrical arc from an electromechanical contactor or switch supplies more than enough energy, which is why switching components are the primary focus of A2L compliance.

Components that do not arc, such as transformers or sealed solid-state electronics that cannot produce sufficient arc energy under any fault condition, typically do not require A2L-specific certification.
However, exemption still requires a documented FMEA showing that no fault scenario can generate ignition-capable energy.

Electromechanical Contactors

LOVATO Electric’s BG series mini-contactors and BF series contactors, including the DPBF series definite purposed rated versions, have completed the LZGH2/8 certification process and are certified under both UL 60335-2-40 (heat pumps, air conditioners, dehumidifiers) and UL 60335- 2-89 (commercial refrigerating appliances).

The BG Series offers three-pole variants from 6A to 12A (3 to 7.5HP at 480V UL/CSA). Coils include AC, DC, and low-consumption DC. Termination options span screw, FASTON and rear PCB solder pin, making the series suitable for compact OEM refrigeration controller enclosures where refrigerant could stagnate near arcing contacts. The BF and DPBF Series contactor line is also A2L certified to extend coverage for larger current up to 150A (up to 100HP at 480V UL/CSA).

Disconnect Switches

LOVATO Electric’s GA Series disconnect switches cover 16A to 125A and are compatible with A2L refrigerant applications. Units from 16A to 40A measure only 36mm wide, while the 63A to 125A ratings use a 70mm body. All versions carry 800V rated insulation voltage, 8kV impulse withstand and 100,000-cycle electrical and mechanical life.

Units are available in direct operating, door- mount and door-coupling versions, DIN rail or screw mountable, and padlockable in the open position without additional accessories. That padlock capability matters more than it used to when the system contains a flammable refrigerant.

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Monitoring Relays

LOVATO Electric’s PMV voltage monitoring relays are also A2L certified. They monitor voltage, current, and frequency in three-phase systems and are commonly installed in HVAC control panels. The range includes the PMV10 for phase loss and phase sequence monitoring, the PMV50 for min/max voltage with phase loss and sequence detection, and the PMV55 for single-phase min/max voltage, covering 208-480VAC at 50/60Hz.

Motor Protection Circuit Breakers

LOVATO Electric’s SM1 series MPCBs are in the process of obtaining A2L approval, which will extend flame-arrest compliance to motor protection across the compressor circuit.

UL 60335-2-40 requires leak detection sensors that activate at less than 25 percent of the refrigerant’s LFL. When concentrations approach threshold levels, the system must initiate ventilation or controlled shutdown.

That requirement changes what an electromechanical contactor does in the system. A mini-contactor controlling a ventilation fan is now a safety actuator. The disconnect switch is the device that isolates circuits when the detection alarm triggers. Because many A2L refrigerants are denser than air, detectors should sit at low points near coil connections, valves and compressor compartments.

Here’s a quick checklist:

Verify LZGH2/8 certification on every electromechanical contactor, mini-contactor and disconnect switch in the refrigerant zone. A component with the right current rating but without A2L certification is a non-compliant ignition source.

Confirm Annex JJ gap compliance
The housing gap dimensions are a physical design parameter. There is no equivalence between A2L-certified and non-certified components of the same electrical rating.

Check VFD listings
Any drive previously listed under UL 508C must be re-specified against UL 61800-5-1 for A2L service. This is frequently missed in system conversions.

Request FMEA documentation from component suppliers
The analysis must demonstrate that no fault condition produces an arc reaching the refrigerant’s self-ignition temperature.

Build leak detection into the control architecture from the start
Electromechanical contactors and disconnectors are part of the safety response chain. Specify them accordingly.

Consider A2L compliance even where it isn’t mandated yet
Some sectors, like data center cooling, have no hard A2L requirement today. But many specifiers in those sectors are already requesting compliant components as an added safety margin, and the regulatory direction is clear. Designing A2L compliance into the BOM now avoids a second round of respecification later.

For decades, selecting refrigerants and electrical components were independent engineering decisions. With A2L, however, they are not. The flammable nature of the new refrigerants means every arc-producing device in the system poses a safety concern, and the standards now reflect that. Engineers who build this understanding into their specifications today will spend less time chasing compliance issues once the equipment reaches the test lab.

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