Guide to safety with insulation tester? (1kv !  - Page 1
Forum section: electronics / beginners

author: algorithm
author_rank: Regular Contributor
timestamp: June 07, 2022, 09:34:30 am
content: Just got a few of these toys. Kinda intimidated by these boys though. The megger and this newer digital meter both can output 1000v.Any advice to ensure I dont zap myself?I didnt really need this, but these were cheaper than a heathkit c1.So I guess my intention was to use these to test big capacitors If I wanted to test that aspect.Are there any other uses for such a device?Guess it might be fun to see if some free "gift" shenzen back alley probe wires really are rated for 1000v?Alternatively might be fun to test a known bad cap backwards? The 4th is coming up.Im not a complete idiot with high voltage, I know of the hand in the pocket technique. I definitely want to exercise caution here though. Ive never had a device that would shoot out that much power I dont think. (Hope).Anyway thanks for any advice, ideas, or opinions.

author: Psi
author_rank: Super Contributor
timestamp: June 07, 2022, 09:42:50 am
content: It puts out high voltage but low current.There is no need for high currents when testing insulation breakdown.Normally these devices put out 1000V at around 1mA.It takes over 30mA before there is a risk of death.So,in theory at least, the device should be pretty safe if you get zapped.If you zap yourself it would feel like a bad static-electricity shock multiplied by 2. But overall pretty mild on the scale of electric shocks. An electric fence hurts way way more.I say "in theory" because I don't know if your insulation tester is a quality brand with known specs.If it's some random china brand with no name then the output current could be anything and therefore it could be dangerous.Just don't be stupid with it, don't shock yourself or others intentionally and you should be fine.

author: algorithm
author_rank: Regular Contributor
timestamp: June 07, 2022, 10:00:24 am
content: Im flattered by the notion of being misconstrued as a bot, but no Im flesh and bone or whatever. LolCool, well yeah 1 brand is "megger". It looks like the big bk precision analog insulation tester. Its neat because it will do a test at 50v or 100v as well as the typical higher levels up to 1kv. The other is a cem dt5500. Seems nice and well made. Although not my field of expertise if I have to ask how to use one. LolThanks again.

author: themadhippy
author_rank: Super Contributor
timestamp: June 07, 2022, 10:06:59 am
content: QuoteOne of the first things most apprentice sparkys experience is being told to hold these 2 wires,and zap.

author: Psi
author_rank: Super Contributor
timestamp: June 07, 2022, 10:14:31 am
content: Quote from: themadhippy on June 07, 2022, 10:06:59 amYep, everyone does it, but I don't want to be the guy who tells someone to shock others.Quote from: algorithm on June 07, 2022, 10:00:24 amSorry, at first I thought the text looked a bit like a bot, especially with the word 'algorithm' as the name.But then i read the post a bit more and decided you weren't a bot so deleted that part of my post.Quote from: algorithm on June 07, 2022, 10:00:24 amYou have nothing to worry about then, should be nice and safe.

author: Gyro
author_rank: Super Contributor
timestamp: June 07, 2022, 08:44:17 pm
content: The main thing to avoid is charging up too much capacitance. Once you get any significant capacitance charged to 1kV, it willbite. It needn't be a physical capacitor, it can be the capacitance between windings on a big transformer, a long length of cable etc.Insulation testers, the good ones anyway, have a bar-graphs on the display to monitor voltage, in adition to the insulation resistance reading. The golden rule is to keep the tester connected after you have released the test button until you can see that the voltage level has decayed (has been discharged by the tester).The bar-graph is also there as a double check. It insures that the test voltage hasn't collapsed under load, so the resistance reading is truly taken at the full test voltage, in accordance with the wiring regs.

author: TimFox
author_rank: Super Contributor
timestamp: June 07, 2022, 09:01:45 pm
content: Of course, a caveat on electrical safety of high-voltage low-current devices is not to be standing on a ladder or high platform when you touch the wires.

author: SmallCog
author_rank: Frequent Contributor
timestamp: June 10, 2022, 10:37:33 am
content: Quote from: Gyro on June 07, 2022, 08:44:17 pmThis!I’ve had a fair whack after testing insulation resistance on a 1000m roll of wire and not realising it was effectively a capacitor

author: armandine2
author_rank: Frequent Contributor
timestamp: June 10, 2022, 11:16:49 am
content: Quote from: Psi on June 07, 2022, 10:14:31 amwhich reminds me how mechanics were told to fault find by having a finger on the king lead from the ignition coil and to flick the points (contact breaker)