When the Refrigerant Changes, So Does the Electromechanical Contactor
The shift away from high-GWP HFC refrigerants is doing something many engineers didn’t anticipate, and it’s forcing a reexamination of electrical switching components that have gone largely unchanged for decades.
For years, electromechanical contactors, disconnect switches and control relays were selected based only on electrical performance, including voltage, current rating and duty cycle. But because many low-GWP alternatives are mildly flammable, a new parameter has appeared on the spec sheet that has nothing to do with electricity: flame arrest.
What’s Driving the Change
As of January 1, 2025, the importation of equipment with R-410A has ceased under the AIM Act’s mandate for an 85% reduction in HFCs by 2036. The replacement refrigerants — R-454B, R-32, R-452B and others — carry an ASHRAE A2L classification, meaning they’re less toxic, flammable and have a burning velocity at or below 10 cm/s. While they’re environmentally superior, they’re also ignitable.
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 Annex JJ maximum gap dimensions, so any flame initiated inside the housing can’t propagate into the surrounding atmosphere. The same logic applies to disconnect switches, control relays and motor protection circuit breakers.
The certification to look for is LZGH2/8, developed under UL 60335-2-40. A component certified under LZGH2/8 proves the absence of any ignition source inside the unit, which enables UL to waive the more onerous Annex FF leak simulation testing at the system level. A component with the right current rating but without A2L certification is a non-compliant ignition source.
Solutions From LOVATO Electric
LOVATO Electric’s BG series mini-contactors and BF series contactors completed the LZGH2/8 certification process under UL 60335-2-40 and UL 60335-2-89, covering applications from compact OEM refrigeration controllers through larger loads up to 150A. The GA Series disconnect switches and PMV monitoring relays are also A2L certified.
The certification to look for is LZGH2/8, developed under UL 60335-2-40. A component certified under LZGH2/8 proves the absence of any ignition source inside the unit, which enables UL to waive the more onerous Annex FF leak simulation testing at the system level. A component with the right current rating but without A2L certification is a non-compliant ignition source.
For a full breakdown of the standards, certification pathway and replacement refrigerants displacing R-410A.
