Are metal body toggle switches safe for mains switching?  - Page 1
Forum section: electronics / projects

author: gabri.peic
author_rank: Regular Contributor
timestamp: December 04, 2021, 01:47:42 pm
content: Hi. I am building a vintage style amplifier and I would like to use a toggle switch as a power switch. I could put it on the secondary side of the transformer but than the transformer would be on whenever the thing is plugged in. It would be the best if I could use it as a hard power switch.But I am worried about the safety of these metal toggle switches... So are they safe to use for mains???Obviously I would use high quality one and ground it to the metal front panel of the amplifier.

author: Ian.M
author_rank: Super Contributor
timestamp: December 04, 2021, 02:08:25 pm
content: If from a reputable manufacturer, and rated for 250V AC, and your transformer's inrush current, yes they are safe when mounted to agroundedpanel.

author: CaptDon
author_rank: Super Contributor
timestamp: December 04, 2021, 02:39:01 pm
content: Well, one would assume so since they have been on almost every amplifier ever made? It should/must be used on a GROUNDED metal panel. If you are a musician you should always have your amplifiers grounded, even more so when playing outdoors. When I play outside I am usually barefoot (kind of a trademark actually) and I have had some serious electrical burns on my lips when I got against a microphone of an ungrounded sound system that was plugged into a receptacle with no ground. The 'hot' wire was touching the metal shell of the receptacle box and putting 120vac on the 'ground'. I have also gotten zapped by the strings on my guitar when the whole 'front line' (lead player, rhythm player, bass player) was plugged into a power strip with the ground pin missing (cut off actually) and the bass amp had a shorted noise suppression capacitor from line to chassis. If the power strip was properly grounded it would have tripped off. BE SAFE!!!

author: TimNJ
author_rank: Super Contributor
timestamp: December 04, 2021, 06:55:17 pm
content: The timing of this post is pretty absurd. I'm building a little plastic test fixture box which with a number of AC mains switches. Yesterday, probably for the first time ever, I wondered "huh, what if the metal bat on one of these switches fails...can it easily become connected to mains?". So, did a quick search on Youtube to see how toggle switches are fundamentally constructed to try to understand the implications of a failure.Found this video:In the end, I think it really depends on the exact switch you are using. With a hard enough blow directly into the top of the metal bat, seems like the "plastic actuator thing" could possibly get crushed enough such that the metal bet comes in contact with mains. In normal use, if the "round nubs" get worn out enough that they break, you're probably safe because there's still the rest of the plastic rectangular thing still intact. This is solely referenced off of the above video.At any rate, if you want to use a toggle switch without a properly earthed enclosure, probably best to pick a plastic paddle version.

author: Ian.M
author_rank: Super Contributor
timestamp: December 04, 2021, 07:00:48 pm
content: .... with a plastic bodr, boss and mounting thread.Alternatively, if it has a metal body, and you are fitting it to an insulating panel, make sure the body is reliably grounded.

author: gabri.peic
author_rank: Regular Contributor
timestamp: December 04, 2021, 08:30:23 pm
content: Thanks guys. I know about the dangers of no ground in audio. I do not play in any band but I am more of an audio tech guy and I did get zapped throughout the metal case of the mixer once on non grounded circuit because of some leakage. Lucky it was nothing serious. It was just some leakage trough the power supply.I plan on grounding the whole front plate that the switch is going to be mounted on.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 04, 2021, 09:17:48 pm
content: Perhaps you could have a small low voltage supply operating a relay so the switch only deals with low voltage? It's not hard to find one that has such a low standby current that's difficult to even measure.

author: Bud
author_rank: Super Contributor
timestamp: December 04, 2021, 10:25:56 pm
content: For vintage type of equipment or replica equipment it would be a SHAME to use plastic switch actuators. Metal toggle switches were used over a hundred years or so, i started my jorney in 1970's and have never heard of anyone been hurt because of using classic toggle switches.Edit: let me make one reservation: do not buy such switches from China.

author: David Hess
author_rank: Super Contributor
timestamp: December 05, 2021, 12:32:20 am
content: There is nothing wrong with using a metal body toggle switch on the line side, but the metal body should be tied to chassis ground which is usually provided through the metal panel that the switch is mounted through.

author: rsjsouza
author_rank: Super Contributor
timestamp: December 05, 2021, 12:49:16 am
content: Same experience here; I have been using metal body switches for a very long time with absolutely to problems at all. Sure, get a switch from a reputable brand.

author: TheMG
author_rank: Frequent Contributor
timestamp: December 06, 2021, 01:03:39 am
content: The only time Ive seen such a switch short to the metal body was when the toggle was subjected to a significant impact, enough to break if off its pivot and drive it down into the innards of the switch. Of course, it was mounted to a grounded chassis and simply popped the mains fuse. So yes, such a failure can happen.