On / off switches - Page 1
Forum section: electronics / beginners

author: Jalca
author_rank: Newbie
timestamp: May 19, 2022, 01:03:26 am
content: Assuming that appropriate soft starting measures are taken where it's appropriate, is it acceptable / good engineering practice to not have a device mounted on / off switch and to use the switch on the wall socket to turn power on and off (e.g. in a power supply) instead?I'm thinking that potential arcing on the wall switch (depending on what is being switched) could still be an issue over time, but I'm not sure of this or whether there are other reasons that may make a device mounted switch necessary / good practice.Cheers

author: themadhippy
author_rank: Super Contributor
timestamp: May 19, 2022, 01:12:42 am
content: Quoteaccessibility,what if the nearest socket is under a desk or behind a cupboard? and not all sockets are switched ,example all of my home ents kit is plugged into a block of 8 un switched sockets,if i turned it on/off from the wall everything would come on.

author: Jalca
author_rank: Newbie
timestamp: May 19, 2022, 02:59:07 am
content: Sorry, I should have clarified. Assuming that turning on and off from the wall socket is what is wanted. If for example, I were to design and build a PSU, is it good practice / acceptable to not include a device mounted on / off switch and just use the wall socket? Is there an electrical / technical reason why the wall switch should not be routinely used for this purpose?Cheers

author: bob91343
author_rank: Super Contributor
timestamp: May 19, 2022, 04:49:13 am
content: I have done that with no problems.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 19, 2022, 11:06:33 am
content: Quote from: Jalca on May 19, 2022, 02:59:07 amWell in my house there is a wall switch for the outlet underneath the kitchen sink for the garbage disposer. It makes sense. Some house with wall switch to turn on/off outlet in the bedrooms. It's OK too. I don't see no harm in most cases but I wouldn't want too many of those switch outlets in my house. Sometimes you are not sure the outlet is on or off because the wall switches are not near the outlets

author: madires
author_rank: Super Contributor
timestamp: May 19, 2022, 11:30:13 am
content: Nothing wrong with not having a power switch in a device and powering it via a switchable wall socket. For example, most power bricks come without any power switch.

author: david77
author_rank: Frequent Contributor
timestamp: May 19, 2022, 11:41:06 am
content: If it is something you want to sell in different markets you should keep in mind that most countries do not use switched sockets.

author: wizard69
author_rank: Super Contributor
timestamp: May 19, 2022, 08:16:29 pm
content: Quote from: Jalca on May 19, 2022, 02:59:07 amTo an extent that varies a lot from country to country. In general and in the case of a PSU; I'd have to say it is universally bad practice. In the case of the NEC I believe that it might not pass muster depending upon several factors. One question would be the proximity of the switch.My NEC knowledge is rather old and frankly not up to date but in the past you had to have a local switch at the tool that was being used or some sort of overload protection for motor driven devices. This largely was applied to motor driven stationary tools as a running tool could overload and thus over heat. A power supply would or could have the same implied risk and devices like welders are required to have a local switch last I knew.In any event if you forget the rules that apply for your area for a bit, I'd have ot ask why would you do this to yourself? Having a switch on a power supply would be the first thing I'd allocate panel space for.QuoteI can't think of a technical reason, I mean it could work, would it meet code requirements I don't know. However if safety and convenience are a factor in your life, a switch makes a lot of sense!

author: Jalca
author_rank: Newbie
timestamp: May 19, 2022, 11:40:29 pm
content: QuoteI've seen audio setups where all devices are plugged into one or two appropriately sized power strips that then go to a conveniently placed and appropriately sized switched wall socket(s). All devices had device mounted switches but were left in the 'on' position allowing the whole system to be switched on or off from the wall socket(s). In this scenario it was more convenient to turn on one or two switches than it was to turn on ~6 - 8. It occurred to me that maybe cutting out the middle man (the device mounted switch) could be an option in circumstances like this. But I was unsure if this would be good practice / allowable or not. One argument for doing this that I can think of would be that the mains could go directly to the trx and perhaps reduce the number of failure points within the device where a mains connection could fail and lead to problems.

author: themadhippy
author_rank: Super Contributor
timestamp: May 20, 2022, 12:26:37 am
content: Quotegreat way to increase the risk of blowing your speakers

author: Jalca
author_rank: Newbie
timestamp: May 20, 2022, 02:55:54 am
content: QuoteOkay, how so? Would muting / disconnect circuits not protect the speakers?

author: madires
author_rank: Super Contributor
timestamp: May 20, 2022, 08:05:59 am
content: Quote from: themadhippy on May 20, 2022, 12:26:37 am... if your amp has no speaker protection (incl. delay).

author: themadhippy
author_rank: Super Contributor
timestamp: May 20, 2022, 10:53:01 am
content: Quoteif fitted yes,but isnt that common on professional equipment, muting if fitted is often only there to let the amp get stable and isnt long enough to let most digital mixing desks boot up.