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SurgeX not guaranteed Series Mode


Senior Member
Nov 2, 2022
SurgeX has become synonymous with making Series Mode Surge Eliminators that totally eliminate a surge. Their claim to fame is that they don't use MOV's (Metal Oxide Varistors) and are therefore non-sacrificial. They also claim that they don't contaminate "ground" because the surge is slowed down in real-time, stored as energy in capacitor banks and safely bled onto the Neutral a few volts at a time.

In 2009, Frontier Electronics (the makers of the SurgeX product line) was acquired by ESP and this product appears to trade on the SurgeX name. The Defenders Series including this product only state that it uses "multi-stage" technology which is "superior to conventional single stage MOV circuitry". So what exactly is "multi-stage" technology?

ESP/SurgeX define the technology used in the Defender Series (see comment)

The multi-stage technology consists of three stages:
STAGE 1: DIVERTER. Using a combination of varistors (MOV's) and gas discharge tubes to divert the surge energy to GROUND.
STAGE 2: EMI/RFI FILTRATION: Often an RLC circuit to reduce noise, but can be as simple as a capacitor.
STAGE 3: CLAMP. Additional MOV's (which divert the energy to GROUND)

Interestingly this is no different than just about every other MOV based surge protector. Even the $10 surge protector you buy in a grocery store often contains these 3 stages and in marketing hyperbole (no one really makes a single stage MOV based surge protector).

What's interesting here is that for years SurgeX has educated consumers by informing about the limitations of MOV's which are sacrificial, work at voltage thresholds instead of all the time, and divert the surge energy to GROUND where it basically contaminates Ground.

It would appear that ESP is trading on the SurgeX name hoping to lure unsuspecting buyers who have come to know SurgeX as being synonymous with Series Mode technology which this device is not. This device then could lure an unsuspecting buyer into a false sense of security.

Earlier this year the combined ESP/SurgeX company was acquired by another company. It will be interesting to see if the new company continues to trade on the SurgeX name. Bottom line, if it does not state that it uses Series Mode (SM), or Advanced Series Mode (ASM) technology then it does not use Series Mode. We have to look beyond the SurgeX name now.
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