Tingle from metal lamp = dangerous?

Lars, to check the leak resistance of mains circuits you need a special "megger"meter.This is usually in the range of Mohms, so usually a normal multimeter shows infinite resistance (sometimes modern digital ones are capable of measuring this resistance).It's very dangerous to use something that gives you (even) a slight shock.If you find it's too much money to have it professionaly repaired (maybe a worn out cable that touches the frame?) then better trash it, than put your life in danger.

-- Tzortzakakis Dimitrios major in electrical engineering, freelance electrician FH von Iraklion-Kreta, freiberuflicher Elektriker dimtzort AT otenet DOT gr Ï "Lars" Ýãñáøå óôï ìÞíõìá news:9645D86505B0E51D7E@204.153.244.156...

Reply to
Dimitrios Tzortzakakis
Loading thread data ...

What does "double insulated" mean in actual practice?

Reply to
Bill Woods

Basically, Double insulated is a little misleading, but in UL/CSA parlance, it means that the internal wiring is such that it would take TWO faults to occur, either of which would stop the product from working, before anything could become electrically dangerous to the user. Usage conditions are also taken into account. Among other things it also means that there cannot be any exposed metal on the product. ALL exposed metal must be grounded, which become a non-essential in double insulated products.

It also means it doesn't need a third "prong", and the blades do not have to be polarized on the two-blade plug, and it does not need a 3-hole outlet.

Pop

Reply to
Pop

Double insulated means they wrapped TWO layers of electrical tape around all bare wires, not just one. That also means the item cost $5 more than if they has only wrapped the wires once.

As to the OP, you mean you still didn't fix that lamp. You posted about it about 2 or 3 months ago. Apparently you have not used the lamp or we would have heard about your funeral by now.

It always amazes me that people will risk their life for a lousy dollars worth of wire and 20 minutes of time, and probably spent an hour posting a message about it.

Mark

Reply to
maradcliff

Not entirely true. The classic example is a double-insulated inexpensive power drill. The chuck that holds the bit is metal, and is not grounded. The tool does not have a third prong grounding conductor. But it meets the definition of double-insulated because the chuck is insulated from the motor by nylon gear-drive. And the windings on the motor are, of course, insulated from the motor frame. So it would take two faults, just as you said. It has no third prong, also as you said. But the exposed metal parts are *not* necessarily grounded.

daestrom

Reply to
daestrom

So they put in nylon gears, which we all know have a very limited life span, instead of using reliable gears and adding a grounded cord. That's just plain stupidity at it's worse. Also the reason I am always looking for the old solid metal drills at garage sales. Not to mention that most new drills have those keyless chucks, and I absolutely despise those useless pieces of shit.

I'd much rather spend the extra dollar or two for the steel gears and grounded cord.

I bought a portable jig saw (saber saw) 2 years ago. It had plastic or nylon gears. I used it maybe 2 hours at most cutting plywood and such. Then I inserted a metal cutting blade and started to cut a piece of steel barn siding. I was cutting the length of the steel or about 8 feet. That stuff is only 22 gauge or thereabouts. I cut about 2 feet when the saw stopped cutting, but the motor was still running. I opened the saw to find the nylon gears completely stripped. After a big hassle, I was able to get the thing replaced thru the warranty, but as far as I am concerned, it's pretty much a useless tool, since I know as soon as I use it for anything more than cutting some balsa wood, the new one will strip too. Just more inferior crap sold by Black & Decker.

Mark

Reply to
maradcliff

Nylon gears can last for decades of use when not abused. Jigsaws are not the best choice for cutting 22 gauge steel. Tin snips or nibblers are a much better choices. For a saw blade to work most efficiently, the material must be significantly thicker than the pitch of the blade. When cutting thicker material the teeth lower on the blade hold the saw away from the material being cut. Without these lower teeth in contact, every time a tooth of your saw hit caught on the bottom of the sheet-metal, it sent a major shock straight up the transmission.

Maybe you have to buy the stuff not in the bargain bin. I like my old Black and Decker drill, but if I ever start doing serious work, I would buy a new one that is lighter more efficient and more powerful.

Reply to
Stephen B.

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.