Puzzling death of a immersion circulator behind a z-wave power plug - Page 1
Forum section: electronics / beginners

author: psycho0815
author_rank: Regular Contributor
timestamp: June 05, 2017, 05:09:21 pm
content: Hi so something weird happened to me yesterday that left me puzzled and i was wondering if you guys can help me.So my immersion circulator died on me. Made some sizzling noises, then a bang and a flash. That's not the puzzling bit. The pump was making grinding noises for a while, so i guess whatever it was grinding, finally gave way and allowed water to get in places, it wasn't supposed to. The puzzling bit is that it was behind a z-wave wall plug that was switched off. The switch on the circulator was on but still that seemed weird to me, so i measured the wall plug with a multimeter and sure enough, when off it reads 25 V Ac. It doesn't seem to be a fault either because another plug i have reads 40V when off.Now as i said i don't think that plug was directly responsible for the circulators death, but it still seems weird. Wouldn't you expect the thing to actually be off, when it says it's off.I was thinking about using one to switch my 3d printer since it doesn't have a power switch, but now i'm unsure.Do you guys have any idea why that could be. I couldn't find any schematics for either of the plugs, but there is an audible click, when it switches, so i'm assuming they use relays.i don't know how that voltage behaves with any kind of load, as i'm not sure how to safely measure that. I don't have any load resistors or electronic load. I was thinking od plugging in a power strip with a lamp and then measure the voltage at one of the empty sockets. Would that work?Any help would be appreciated. I hope that is all understandable. English isn't my first language and i had to look up some words.the brands of the switches are:taphome easyplug, though google says it's manufactured by wintopaeontech smart switch 5

author: SeanB
author_rank: Super Contributor
timestamp: June 05, 2017, 06:14:01 pm
content: Easy, the switch is in the neutral connection. Thus when off the line is still connected, and thus there is mains voltage available betwen the internal electrics and the ground connection, even though with the neutral disconnected there is no current flow. If you measure between the conductors and the ground with the switch off one will show mains voltage, and the other only a low phantom voltage.

author: psycho0815
author_rank: Regular Contributor
timestamp: June 05, 2017, 06:35:57 pm
content: You're right i just measured it again and one of the conductors shows 230 against ground. I flipped the plug around and that is gone. also the voltage is down to like 3V. I just stupidly assumed that the plug would switch both wires because in Germany that's the only save way to do it.But since the neutral was floating there still shouldn't be any current right? So my circulator still shouldn't have had any current to kill itself? I mean i guess it's possible that the life wire was shorted with the casing which is grounded, I only have an FI in the bathroom not the kitchen so i guess that's a possibility.So can this kill any other devices? should i make sure the plug is inserted so the life wire is switched, or is there no danger because no current can flow anyway?

author: ebastler
author_rank: Super Contributor
timestamp: June 05, 2017, 06:56:58 pm
content: I think SeanB had explained it nicely in his reply:Quote from: SeanB on June 05, 2017, 06:14:01 pmIf you insert the switch such that it cuts the live connector, no failure should be possible. But I think that is just asking for the next mishap somewhere down the line, when somebody who is not clued in on this disconnects the switch and puts it back in the wrong way. I would look for a switch whch interrupts both connections. As you had already stated, that's the only proper way to do it, with the symmetrical jacks and plugs in Germany.

author: psycho0815
author_rank: Regular Contributor
timestamp: June 05, 2017, 07:24:02 pm
content: Problem is, that that detail isn't usually included in the technical specs. It's really weird, that there seems to be no regulation on that in the eu. Considering that they seem to be regulating anything else.

author: SeanB
author_rank: Super Contributor
timestamp: June 05, 2017, 08:10:46 pm
content: Problem is electrical regulations, which in one country require disconnection of both active and neutral, and in another country disconnection of the neutral is prohibited, both applying to the same class of plug in appliances. either way in one country you are at fault, but the approval in the EU allows both.Yes, a polarised socket output is a lot better, as it reduces the chances of a disconnected neutral, like in your case, causing an appliance which is nominally "turned off" to either cause unwanted operation or failure due to a low resistance connection to the safety ground conductor for some reason.