aluminum chassis and IEC connector - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: April 07, 2022, 07:22:30 pm
content: So I have a IEC connector that lost its retention spring thing that would act as a shitty secondary ground (other then the fast on leading to lug that is bolted to chassis.I don't know if I like a fast on for a variac (it might rumble), so I wanted a secondary ground. I thought the best way might be to take a solid copper wire, solder it to the shield of the IEC filter, then bolt that to the chassis. That way there are no DIY crimps anywhere in the secondary ground.If I want to press a copper loop into an aluminum chassis, what is the best option? I thought to make a split galvinized bolt, bolt it to the chassis with a star washer and al-nox, then put the solid copper wire into the groove cut into the bolt and then tighten that down with another nut, rather then trying to sandwich the copper wire between the bolt and aluminum chassis.Or I also thought to solder a copper bolt directly to the shield so it has a stud and use two ring terminals with a stranded wire, ring crimps and then use penetrating loctite to make sure the bolt does not loosen.Has anyone ever seen a fast-on connector come loose from vibration before? I don't like how there is no good way to retain them. Normally I don't care but this is just a big variac in a box.. does anyone see a safety problem with relying on a brand name fast-on connection as the ground here? I used a good crimp tool and TE brand connector, but even if its speced properly, it seems a little wimpy for an all metal chassis.Maybe putting some electric silicone on the end of the plastic crimp housing would act as good enough a retaining compound to make me be at ease?This is for a 20 Amp variac, its the highest power circuit I have worked on yet DIY. I made all the ground connections by removing the paint with a dremel stainless brush, cleaning with alcohol, then wetting with al-nox and scrubbing it in with a dremel stainless brush, cleaning up the splatter around the ground point and giving it some fresh al-nox on top before bolting it down. They read very low and I would likely check the ground connection before use after I stored it for a long time.. so my main concern is that fast-on coming off during use on heavy loads because of vibration.I also thought to drill a hole in it so I can lock it into place with a bent wire (u-clip)

author: mikerj
author_rank: Super Contributor
timestamp: April 07, 2022, 07:56:37 pm
content: You can get FASTON female connectors that include a latch that engages with the hole in the middle of the male blade e.g. TE Connectivity 170381-1

author: coppercone2
author_rank: Super Contributor
timestamp: April 07, 2022, 07:58:23 pm
content: that would increase my confidence alot, I need to study it. Looks like a potential game changer.https://www.te.com/usa-en/videos/consumer/positive-lock-overview.htmlDo they have these positive lock ones with brazed barrel crimps rather then folding stuff?

author: coppercone2
author_rank: Super Contributor
timestamp: April 07, 2022, 08:13:14 pm
content: this in yellow would be nice, I don't think its aroundhttps://no.rs-online.com/web/p/spade-connectors/6803063

author: themadhippy
author_rank: Super Contributor
timestamp: April 07, 2022, 09:35:45 pm
content: QuoteWhat size cable are you using? blue is good for 2.5mm2yellows 6mm2territory

author: Terry Bites
author_rank: Super Contributor
timestamp: April 07, 2022, 11:10:59 pm
content: Always use a serious ratchet crimp tool and get medieval on them suckers. You're looking to create a gas tight connection. Chech you know how to use the pinched flesh release lever. Faston Fastin spades and blades use a locking latch. They call it the lance. Thankfully you can bend back the lance to release your tab.Oh joy.https://www.te.com/usa-en/plp/faston/ZnaA.html

author: coppercone2
author_rank: Super Contributor
timestamp: April 07, 2022, 11:41:24 pm
content: Quote from: themadhippy on April 07, 2022, 09:35:45 pmI was using 12AWG wiring with yellow crimps. I defiantly don't want to skimp on ground quality (has a beefy 12AWG cord too).Yeah, I don't have trouble imagining the crimp I made is good, its just the fact that the transformer will likely buzz bothers me with a non-locking fast-on connector. I thought I really should have something with screws and loctite.And IDK if that filter can explode from a transient overload (the fuse is after), so could it dislodge the ground wire and then leave it shorted... kinda wonder if I should add a TVS somewhere far away from the filter.Maybe a drop of silicone on the front of the connector between plastic and wire and then another drop near the ground pin and the body of the connector will be good enough? I wonder if I am being paranoid. This usually seems like the standard for ground wires (i.e. in APC power supplies, they do buzz a little).