Sorry if this is not the area to ask such questions but you have to start somewhere.
I got a DAB radio for Christmas and decided the place to put was the kitchen. I plugged it into the mains via the supplied double insulated mains adapter and while positioning the aerial I felt a mild tingle. I measured the voltage with my cheap home DVM and got about 90Vac between the aerial and mains ground and also the sink top. I took it into work and asked one of the technicians to verify the reading. He managed to get 95Vac between the aerial and the mains ground on his work bench.
I return the radio to the supplier and got a different more expensive make/model.
Thinking this would be OK I set the radio up in the kitchen and this time got a mild electric shock when I checked the aerial with the back of my hand.
Took the radio to work and this time the reading between the aerial and mains earth was 99Vac with a current flow of about 1.5mA ac.
OK the shock obtained for these radios would not normally cause to much of a physical problem but I wondered about our patients; they are not always in top physical condition and not always fully "awake" . Also what would happen if a component failed and the current flow to earth from the aerial increased to over 20 or 30 mA ac.
Hence the questions Is it normal for equipment powered via these plug in mains adaptors to "float" at such a high voltage? Is this a danger? If not why not?
Leakage current through "cheap" mains adapters is a problem, the voltage they float at depends on physically where-abouts in the transformer the leakage is occurring - which in reality is a lot of small leaks distributed around the layers of windings. This is why medical grade battery eliminators are essential in medical equipment. The allowable leakage current for domestic appliances is very high as it only expects an accidental, momentary touch from a conscious person who can pull their hand away. See BS 3456 for details.
Is it a danger - no as it is the current that is the actual problem and they current path is usually quite high impedance so it might make you jump but not do you any harm. Even so it is not pleasant but still legal. Robert
My spelling is not bad. I am typing this on a Medigenic keyboard and I blame that for all my typos.
"Thank you for sending the information on the DAB Radio problem. These are obviously dangerous and you should report the fact to Dundee Trading Standards as soon as possible. They almost certainly would fail the Low Voltage Directive (LVD). Can you let me know the Manufactures name and the model number please. See comments by John Davies who is one of the expert members of EMCIA and EMCTLA. Look forward to more information.
Cheers Alan E Hutley Editor The EMC Journal
The statement that there is a double insulated mains adaptor suggests that this is a Class II device, meaning there is no earth on the product, perhaps the earth pin at the plug is plastic, not metal. This is guess work, not knowing the product or why the user would suggest this product is a double insulated (perhaps Patrick has seen and understood the two concentric square symbol).
This has to be reported/challenged. The manufacturer(s) has to be challenged and I would suggest that a knowledgeable Trading Standard Officer has do this instilled by the user. I would like to see and challenge the Declaration of Conformity, it's test report, etc. There is the European RAPEX site which reports dangerous products. It may be on there or it may about to be put on there! "
Hence to report to our local trading stardards people.
Let's hope that this is the start of a Massive Campaign to rid our hospitals, offices and homes of the hundreds of thousands of potentially unsafe electrical garbage items that (despite all the "stringent" laws available) have been imported in recent years!
To my my mind, someone has been turning a blind eye (or a back-hander) somewhere. In other parts of the world, stuff gets inspected as it comes in (one in ten, one in a hundred, a few in each consignment etc.) ... so why not here? Oh, I know ... because we are led to believe that all is well as long as the "CE" symbol is there to "protect" us. Yeah, right.
My old Philips CRT TV suffered from the same problem, about 60V from the inner aerial connection to earth. Very annoying to get a shock when you plug in a video recorder!! This problem cost only a few pence to fix, why this was not done at the design stage, I don't know.