Two DC units

A few days ago, there were questions about using two DC-producting machines at the same time (didn’t find the original thread, sorry). I asked the Hinkel Company and Fischer engineers their opinions. The following is their response to my question.

Key in this is whether your machine has a “DC-circuit return” or an actual “earth-ground.” I understand this difference, and I’m assuming most people do, but if not someone else or I could explain the difference.


I have heard of operators using two machines at the same time and having no problems, and they only use one sponge electrode between the two.

[using one “ground” only] The one thing that the electrologist should realize is that the sponge electrode is getting twice as much (assuming the galvanic levels are equal on the two machines) hydrochloric acid build up on the sponge electrode which can lead to a burn if the exposure is for a long time and the contact area of the ground electrode isn’t large enough. I might suggest rinsing the sponge pad out during the treatment to minimize the risk… I’m going to forward this to Mark Van Orden for his more expert commentary.

Unless both epilators share a common circuit ground, in a current-regulated device the Galvanic output would not likely work properly (RF is a different matter entirely).

The newer Fischer epilators (CB-X and SE-5) isolate the circuit ground so I doubt this would work; I suspect the unit without a connected indifferent electrode wouldn’t even be able to detect an insertion, but I’ve never actually tested this. Don’t know about the Hinkel Blend epilators, they may have the circuit ground and earth ground common.

You could test it yourself by connecting a milliamp meter between the needle on two units and a “shared” indifferent electrode on one of them.

Our epilators have the sponge electrodes at earth ground so they can operate with a shared ground… I’ll check out how the Fischer’s work when I get a chance. With our epilators I guess there’s a possibility for some problem if a patient holding a sponge electrode from one of our units grabbed onto something "hot’… but not sure that would be a very likely scenario in this day and age.

Interesting you should pick up this thought process.

As it happens, I had a bit of trouble with my machine yesterday during a session. I almost never work in automatic. I am almost always using a pedal. But once or twice I have used automatic while working in blend, to get around the crappy ergonomics of my setup and yesterday was one such occasion. All went well for most of the session, and then, it seemed to be triggering early. And then it began triggering when the probe wasn’t touching skin at all. I ended up turning off the machine and back on, and all seemed to go back to normal.