Brian 60335 isn’t well written in this regard in my opinion as it mixed two completely different tests in the same clause
Clause 16.2 is a mains voltage earth leakage test done at 1.05x rated voltage (similar to clause 5.7 in 62368-1) This test has limits for “leakage current”, but there is also a measurement circuit through which this current is measured. Clause 16.3 is a Hipot withstand / Electric Strength test done with an applied test voltage (similar to clause 5.4.9 in 62368-1) This test has no limit on current -the only criteria being that no breakdown will occur. There a number of hipot testers available that will give 5kV ac/ 6kV dc and 100 mA of leakage current for the 2nd test – the 1st test needs a few passive components and a decent multimeter Best regards Charlie Charlie Blackham Sulis Consultants Limited Tel: +44 (0)7946 624317 Web: https://sulisconsultants.com/ Registered in England and Wales, number 05466247 From: Brian Gregory <[email protected]> Sent: 13 March 2026 23:12 To: [email protected] Subject: [PSES] Fw: Re: [PSES] Dielectric test, electric appliances Thanks for the replies, and Hi Doug! Agreed, I can't think of an MOV worth buying that would survive a 1200-1400V dielectric test. We might install jumpers to bypass the MOVs, and megger the completed boards. Note I did find a copy of UL 60335-1 (3rd edition) and section 16.2 has current requirements. All below 1mA, except for 3.5 mA for "STATIONARY CLASS I MOTOR-OPERATED APPLIANCES." which still sounds low. There's a section stating that Class 1 Heating appliances tripping current is 0.75 mA per kW of rating, which is more in the ballpark. Still very much a WIP. happy weekend all, Colorado Brian ---------- Forwarded Message ---------- From: Douglas Powell <[email protected]<mailto:[email protected]>> To: [email protected]<mailto:[email protected]> Subject: Re: [PSES] Dielectric test, electric appliances Date: Fri, 13 Mar 2026 16:04:48 -0600 Richard, I believe the MOV, or any type of protection, may offer some level of surge protection; however, factors such as lead length will limit its effectiveness, particularly concerning other parts of the mains connection within the larger building. The primary goal is to have the surge protection as close as possible to the equipment it is meant to protect. In larger facilities, the line impedances and other parasitics will significantly influence the protection results. From a standards perspective, quantifying these factors is extremely challenging. ~Doug Douglas E Powell Founder & Principal Consultant Vertex Compliance Consulting<https://bit.ly/45BXk3Y> (VertexCC) Laporte, Colorado, USA LinkedIn<https://www.linkedin.com/in/realdougpowell/> Colorado Registered Business | Entity ID: 20191778678 (UTC-06:00, US-MDT) On Fri, Mar 13, 2026 at 2:44 PM Richard Nute <[email protected]<mailto:[email protected]>> wrote: Hi Derek: I guess I am wrong about the MOV subjected to the hi-pot test. Thanks for correcting me. However… the MOV is there to protect the equipment from overvoltage. Doesn’t it protect all equipment that is connected to that branch circuit and ALL of the 120-volt premises system? I think we only think of the immediate load. The MOV must protect ALL of the distributed circuit, not just the load. True? Thanks, and best regards, Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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