Amazon UK's idea of a safe 380V isolator switch! - Page 1
Forum section: electronics / general

author: Gyro
author_rank: Super Contributor
timestamp: September 15, 2020, 09:19:49 am
content: Just in case anyone was any illusions about the degree of care Amazon puts into verifying the safety, quality, and adherence to standards of the products it sells...Spotted today in the Amazon UK daily deals, a "4 Pole Double Throw Electric Brake Safety Knife Switch, Electric Brake Safety Closing Switch, 380V 100A". Forget about dodgy CAT rating silkscreen on DMMs, this one belongs in the Victorian era - only they would have constructed it out of decent materials!https://www.amazon.co.uk/NiceDD-Double-Electric-Safety-Closing/dp/B081CLNB4S/

author: JackJones
author_rank: Regular Contributor
timestamp: September 15, 2020, 09:37:36 am
content: Amazon is no different to eBay and the likes these days. Full of junk, and you can't even filter out third party sellers.

author: WattsThat
author_rank: Frequent Contributor
timestamp: September 15, 2020, 05:18:36 pm
content: Quote from: blueskull on September 15, 2020, 10:05:35 amYou were using it incorrectly. It’s a service disconnect required by code, and it is not load make/break rated. It must be within sight of the device it is powering.Turn off breaker, remove and rotate plug-in, padlock in place with name tag to meet OSHA lock out, tag out requirements before beginning any work the device.

author: MrMobodies
author_rank: Super Contributor
timestamp: September 15, 2020, 10:31:39 pm
content: QuoteJoke: I like the name, when the handle overheats and melts off, safety is broken, then the 4 pole conducturs knive's into you and nicely throws you back with double the force until youbrakeinto some wall and you're dead.

author: Monkeh
author_rank: Super Contributor
timestamp: September 15, 2020, 10:41:34 pm
content: Quote from: WattsThat on September 15, 2020, 05:18:36 pmFaulty workflow.If you can't lock off the breaker and the isolator isn't load rated, then you can't pull the isolator because you can't verify the breaker is off, because it's there and you're here.Also breakers aren't intended for load switching either.

author: pigrew
author_rank: Frequent Contributor
timestamp: September 15, 2020, 11:09:00 pm
content: My wife's parent's building (condo-style) has a fused double-pole knife-switch outside every unit as a power-disconnect (near Nanjing, China, single-phase 220V, approx 32A built around 1980). When installed properly, the knives should be connected to the load, so they are not energized once the switch is turned off.It's "touch-safe" if you don't put your fingers between the slots.And it's about 2m above the ground, so young children shouldn't be able to touch it.(and the interior circuit fuses/breakers were mounted on a wooden board just inside the front door (before I ripped them out as it was a bit too combustible for my tastes)).

author: AVGresponding
author_rank: Super Contributor
timestamp: September 16, 2020, 05:45:30 pm
content: Quote from: Monkeh on September 15, 2020, 10:41:34 pmNo, but they'll handle it better than the isolator in this case. The load should have its own integrated power switch, and if it doesn't it should have a proper rotary isolator.I'm guessing in this case the load is pretty small, say <1kW. I see no reason for not using the breaker to switch it off, given servicing isn't going to be more than what, a couple of times a year?

author: Monkeh
author_rank: Super Contributor
timestamp: September 16, 2020, 07:22:16 pm
content: Quote from: AVGresponding on September 16, 2020, 05:45:30 pmThey don't use rotary isolators, and no, we're talking about much bigger loads than that.You also missed my point in order of operations entirely.

author: janoc
author_rank: Super Contributor
timestamp: September 16, 2020, 07:42:50 pm
content: Oh damn, these look much nicer than the cheapo plasticky junker I have got. (one like this:https://www.aliexpress.com/item/4000419445254.html)Pity I haven't seen these earlier, that would have been perfect for our project. And no, we aren't using them for mains, the most these would see is 5V - it is for an educational game on alternative energies and the client wanted a "suicide/Frankenstein switch" there to turn part of the simulated game field on and off.

author: Haenk
author_rank: Super Contributor
timestamp: September 16, 2020, 08:03:35 pm
content: Hey, that Aliexpress one says "Qualified", so it *has* to be great.And I really like those "ready-to-be-touched-and-killed" screw terminals. They really know how to speed up natural selection.

author: janoc
author_rank: Super Contributor
timestamp: September 17, 2020, 09:39:29 pm
content: Quote from: Haenk on September 16, 2020, 08:03:35 pmYeah, it is a cheap plasticky junk. However, given that these are being made, even in three phase versions, these types of switches have to be approved/allowed to be used somewhere in the world? Not necessarily for domestic use by unqualified doofuses, though.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 18, 2020, 01:55:53 pm
content: Quote from: Monkeh on September 16, 2020, 07:22:16 pmWell, they really should. For domestic window mounted AC?No I didn't, I simply wasn't addressing that point.

author: Raj
author_rank: Frequent Contributor
timestamp: September 19, 2020, 02:13:27 pm
content: Ain't that problematic when the cover is on.Just connect the "generator" and "power grid" to contacts inside the black rectangles and the "knives" marked by red, to house's "power in".This way, when the knives aren't connected to anything, they aren't live.In India, we have similar thing but fully covered (eg-https://www.ebay.com/c/2254488112)

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 19, 2020, 02:18:09 pm
content: wow,you don't see those anymore where I live, and it's considered a 3'rd world country

author: Gyro
author_rank: Super Contributor
timestamp: September 19, 2020, 07:10:29 pm
content: You've got to love those 100A rated screw terminals though... and as for the strain relief.I was wondering what countries were still using them though. They did seem to be a strange choice to be selling on Amazon UK, let alone on a daily deal. I wonder if that's a conscious selection or some sort of algorithm.

author: Labrat101
author_rank: Unknown
timestamp: September 19, 2020, 08:06:32 pm
content: I don't see any problem with thisIt was good enough for Frankenstein's Lab ..mind you he did have a better handle on his .

author: Raj
author_rank: Frequent Contributor
timestamp: September 20, 2020, 05:19:56 am
content: I don't know much about UK's culture, but isn't everyone there, given electrical classes in school?If those are scary, I bet, "kitkats" will give you a heart attack just by a single look. All houses in India have those as mandated (quite rare to have something mandated by law, in the field of electricity) by the law.They are connected right after your electricity meter.What's more, whenever you have a guy with buzzbox welder or marble floor grinder, at your house, they pull the kitkats out and insert their tool's wire into them, so that their tools have the shortest path to power and no other device is putting load on your meter.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 20, 2020, 02:53:09 pm
content: Quote from: Raj on September 20, 2020, 05:19:56 amNo. You'd have to choose to study electronics as part of physics, and electrical engineering is something not taught in schools, but as either an apprenticeship or for more advanced stuff at university.The "kitkat" as you refer to it is called a "bullet" here, or more appropriately a cutout, and will be sealed with a tamper-evident crimp or plug. It is an offense here to tamper with such equipment; it is the property of the electricity supplier.If any tradie tried to pull mine in order to power his/her equipment, I'd tell them to get out, immediately.