Using equipment without ground on mains - Page 1
Forum section: electronics / testgear

author: JanJansen
author_rank: Frequent Contributor
timestamp: June 12, 2015, 03:33:05 pm
content: Hi, if i buy a scope or multimeter, do i need ground in power cord (220v) ?Here in Holland we dont have that.Manuals saying it needs ground, i,m not measuring 1000 volts or something, so whats the risk ?greetings

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 12, 2015, 04:01:57 pm
content: I thought most civilized parts of the world had converted to proper grounded mains power outlets.Do you not have the "Type F" mains connectors?http://www.worldstandards.eu/electricity/plugs-and-sockets/f/

author: ebastler
author_rank: Super Contributor
timestamp: June 12, 2015, 04:02:48 pm
content: Quote from: JanJansen on June 12, 2015, 03:33:05 pmHmm? I do seem to recall that power outlets in the Netherlands look just like ours in Germany, with a protective earth connection on the outer contacts. Wikipedia also suggests that:http://de.wikipedia.org/wiki/Schuko#/media/File:Steckdose.jpgHow old is that building you are in ?

author: JanJansen
author_rank: Frequent Contributor
timestamp: June 12, 2015, 04:14:42 pm
content: No, only in the kitchen, and new houses have it.I have a long earthed cable in house for my recording studio upstairs, i dont want more cables cross the house.

author: TimFox
author_rank: Super Contributor
timestamp: June 12, 2015, 04:23:28 pm
content: Any modern device with a line filter (usually built in the IEC-style power input connector) will have a capacitor from each of the line and neutral poles to the chassis. Without a good ground to the chassis, this puts 1/2 of the supply AC voltage (110 V for 220 V mains) on the chassis with respect to the building ground (wherever it is), in series with a reasonable size capacitor (regulated to avoid lethal shocks for this case). Once at work, at a field installation where the external Diesel generator connections were not properly grounded, we referred to this as the "Dan effect", i.e., "It's really hard to shock Dan, but...". The computer was connected to a non-existent ground, but the interface/control was grounded to large metal equipment and Dan touched both boxes, to his dismay.I had a similar problem in my basement with an ungrounded outlet (which I fixed for this reason) where I touched the chassis on a piece of test equipment and the sheet metal heating duct (at least, US is only 120 V so the shock was only from 60 V). Note that there were several loads connected to the outlet strip, so there was more than one capacitor involved.

author: ebastler
author_rank: Super Contributor
timestamp: June 12, 2015, 04:27:21 pm
content: In Germany you find older buildings which do not have three-conductor wiring, but do have the outlets with separate ground connector (connected to the neutral wire at each outlet). Is this what you have in your house? Then you should be OK to connect a scope. Otherwise, can't you retrofit modern outlets, keeping the two-conductor wiring, in this way? (Check with a qualified electrician whether that's OK under your building code!)

author: JanJansen
author_rank: Frequent Contributor
timestamp: June 12, 2015, 04:50:00 pm
content: Yeah, i should hire a electroman to install it in my living room, dont know how much it going to cost.

author: MiataMuc
author_rank: Regular Contributor
timestamp: June 12, 2015, 08:25:18 pm
content: ... while others tape the ground of their equipment(hum or doing things with their oscilloscopes they should not to)