I've been in my disaster of a house for almost 26 years now . I've seen several members who collect old switches and receptacles talk about installing them in their future homes . PLEASE DON'T !!!! In the past year I've had to replace 2 switches and 3 or 4 receptacles . I currently have a couple of seldom used switches that "sizzle" when 1st turned on unless you kinda jiggle the handle !!  The last thing you need is to have your house burn to the ground from a house fire . The replaced receptacles would get warm/hot after use as would the plugs .  The new ones are WAY tighter and are still cool after use .

 If you want to collect this stuff for display , fine but DON'T put it into daily use !

It depends on the quality and wear state of the exact device in question. Many wiring devices made in the 50s...90s which still exist today, will in fact be more reliable and safe than many wiring devices made today. Some won't whether due to being cheaply made back in the day, worn to oblivion, or both

Examining and evaluating the wiring device on hand is up to you

From a technical standpoint, the NOS and used examples in good condition (you will have to evaluate them yourself) should be fine to put in use but anything heavily used or worn out should be for display only. The old snap toggle switches were arguably better than the modern quiet toggle switches as they had a strong spring to ensure the contacts opened or closed quickly regardless on how you moved the toggle. Modern quiet switches do have springs but they aren't as strong.

Now, most jurisdictions here do require more modern wiring devices in order to meet modern code requirements. For example bathrooms and kitchens require 20A GFCI receptacles, most residential receptacles are required to be tamper resistant with shutters, and a lot of breakers are required to be AFCI. These are all features that were either rare or nonexistent when most vintage wiring devices were made.

A compromise could be to use new wiring devices but specify ones that look vintage. Most builders use all white Decora switches and receptacles but the classic toggle switches and duplex receptacles are still available. One could even use brown or black devices paired with ivory or stainless steel cover plates, which looks a bit more vintage compared to the all white Decora look. 

I am coming from the 230V side of the world, and specifically from Israel (which have similar, but not exactly identical codes to most European countries). My answers are based on what we have here + understanding of what you have in the US based on what i read online



Switches have not changed much in more than half of a century. (A century ago switch handles were made of metal, the step from that to non conductive material was indeed a significant step in safety, but not much happened since)

One could argue that the older switches had exposed metal screw heads on their face plate which are not grounded (here and in most of Europe there was no requirement to ground device boxes which are hidden inside the wall, and since the late 60s...70s all the boxes were made of plastic), while new switches are designed in a way that does not have exposed screw heads. However, according to the latest IEC standards (general ones, not specifically for wiring devices), screw heads are exempt due to their size



Sockets have went through some design changes :

 - Making the socket face recessed, while it was nearly flat in the past. This change prevents touching the pins of a partially inserted plug. It is fairly rare (i know only about Israel and Switzerland), in other countries either it was recessed since the beginning (CEE sockets), or the changes were done in the plugs only (Britain, Italy), or still not done at all (USA)

 - Shutters. To the best of my knowledge, here they are required only in kids-specific areas such as kids bedroom or school. In other countries, even if generally required, worth checking the code as rooms with restricted access might be exempt. Which might include exactly the area of interest, such as a basement

 - Some vintage (~70s) sockets here had an early type of child protection. It was not shutters as we know them, instead, the socket face had to be rotated for a plug to be inserted. You would insert the plug partially, rotate, and then the holes to fully insert it line up. I dont know whether this protection still counts as shutters nowadays, but obviously you can install such socket in a location where shutters are not required

 - Changing the shape of plug pins at a late stage after decades of the standard existing. This is unique case to Israel, it affects plug compatibility but has no safety implications



GFCI sockets (USA) : To my understanding, you can install a GF breaker in the panel or one modern GF socket, and connect whatever vintage sockets downstream from it



Breakers (Simple circuit breakers - Overload and short circuit protection) :

There have been very significant improvements in the reliability and safety of circuit breakers throughout the 70s and 80s, and to a lesser extent 90s. (Talking from my observation on 230V European style breakers). Many old breakers (before the improvements) had significant problems that were eliminated in later designs :

 - Mechanism jamming (70s, common to a few manufacturers)
 - Breaker body not held together solidly enough, and could disintegrate as result of mechanical stress or a violent tripping event (70s, problem with one manufacturer)
 - Contacts inside can remain welded together while the handle is in OFF position (70s, problem with one manufacturer)
 - Inadequate arc extinguishing components (70s, common to a few manufacturers)
 - Three phase breaker can trip internally on one or two phases only (70s, common to a few manufacturers)
 - Openings around handle allow direct line of sight deep inside, such that an internal arc can shoot outside (up to 80s, common to few manufacturers)
 - Screw terminals are open to touch when the panel cover of the board is removed (up to 80s, common to few manufacturers)

Those are sufficient reasons to use new breakers generally

Getting to know specific breaker models from specific manufacturers, you can pick the few that were very good already in the 70s, or early models of modern breakers that have all modern safety in place, that started appearing in the 80s. You might choose not to reuse them in something new anyway, but this is still useful knowledge to decide whether an existing install is worth replacing just in case, or can be left as is

Some old breakers with some of the deficiencies stated, might still be fair enough to use as a switch, where the actual protection is provided by another breaker upstream

Another unknown variable with old breakers is, how many times they had to extinguish short circuit arcs throughout their life, which means how much life is left in them. You might not know this unless they are NOS or you had them in your house from new



AFCI breakers :

If your code requires AFCI breakers, you can install the entire setup of vintage breakers on a circuit which is protected by an AFCI upstream

Personally i think that AFCI breakers are overrated. Well, they do indeed catch some fault scenarios which are not detected by anything else, however, code aside, i would not consider ANY electrical installation as being unsafe just for the fact of not having AF breakers. There are many other things about an installation that really do have significant effect on safety, including regarding arc fault scenarios

They started showing up in codes in Europe here and there. In many places as a recommendation only, or only for bedrooms etc

Israeli code does not mention them, and it better stay this way !



GFCI breakers :

GFCI (RCD breakers) have been required here since the 80s or so, though there are exceptions (for example, in many cases 3 phase circuits or circuits above a certain amperage are exempt). There have been one change in the breakers themselves worth mentioning :

 - The original RCDs from the 70s...2000s are Type AC. They will trip to an AC leakage current, but in case of a rectified half wave (such as, a short from the output of an HF ballast to the luminaire body), they will trip only in one polarity. So there is chance of the breaker not tripping depending on which pole of the DC is leaking to ground. Such RCD is safe to use and provides full protection as long as it is not used to protect line-voltage electronics that contain rectifiers

 - In later years (2000s 2010s) the RCDs were redesigned by adding a rectifier bridge before the tripping winding inside - the new ones are Type A. This way it will trip regardless of the polarity of the leakage current

In most RCBOs, and in the USA GFCIs i seen online, the entire tripping mechanism is electronic. This makes them less reliable than RCDs, which are entirely electromechanical devices (except the 4 diodes in type A devices, but that does not impact the device reliability) - In particular, as they are unable to trip under improper line voltage conditions - if they dont get intact line voltage to power the electronics. An electromechanical RCD will trip at its rated leakage current even if it is supplied just by an AA battery

Do you have electromechanical GFCIs in the US ?



Voltage sensing ELCB breakers :

This breaker is indeed incompatible with basic safety requirements, as it requires wiring a high resistance device in series with ground conductors of a circuit. It is only possible to use safely as a switch (with ground wired properly, and therefore the ELCB function not working)

Note - "Current sensing ELCB" is just another name for the modern RCD, and are not a problem



Modern devices that look vintage - I dont think this is suitable for those who Wide-lite addressed
 - Most 50s 60s wiring devices dont look particularly vintage to the average viewer. He will never see the difference between some vintage device which has similar to modern form factor, vs. a common modern device
 - For who actually does know about vintage devices, the modern look alikes are as good as fakes

I haven't installed them, but i have a bunch of older receptacles and switches.

These things are made from bakelite with a ceramic switch or outlet body underneath. Even when they fail, there is nothing to catch fire.

I'd also comment the problem of old receptacles/switches is certainly more acute in 120V countries due to everything working at 2x current compared to 230V.

If some vintage electric component still can be used depends more on manufacturing quality. I have some 'piano key' toggle light switches, may be approximately 40-50 years old in my home, somewhat dirty and yellowed, but still pretty much OK, and I like the action, so no plans for replacement. But  gypsum walls here, so not much fire problem if anything goes wrong.

 

Things can go wrong with anything anytime though

We have here new(ish) switches from the company Nisko which tend to open a tiny gap between the contacts after being switched on, so continuously arc in series with the load. I have seen those fail in different states, ranging between failure to close the contact at all to full meltdown

The even better part is, that years after this problem already existed, they introduced a new range of devices, this time it's not their own production but import from China. Completely different design. And those too have the exact same problem

I am yet to see ONE switch from the 50s...90s which has this problem

Agreed, and professional installation doesn't mean a thing. My perilex cooker outlet (brand new install by the housing corp, 1 phase 230v 32a divided over 2x phase 2x neutral) held the plug suspiciously lightly. I had to move the thing to a more practical location. Upon removing it, i found out:
- 1 contact was bent forwards or something so it would contact but not clamp down the plug prong
- 1 wire was stuck *behind* the screw connection for it, contacting it but not screwed down
- 1 wire barely screwed down.

All of this stuff is fire safe with a gypsum block wall that it was mounted in, but it would have been a matter of time before the outlet would char and go up in nasty acrid smoke.

But if you're gonna reuse old stuff, just give it a good load test. Load it up to the absolute maximum rating for 15 minutes and see how much it heats up. It should not get any warmer than a modern switch or receptacle. It is not uncommon for outlets to slowly lose their contact pressure over the course of decades of plugging in and out plugs, so they get a higher resistance and therefore more heat production.

What you describe here is an electrician purposefully miswiring a receptacle (receptacle made for 3L+N connection wired as 2x1L+2xN), not in some closed-use special application, but just a receptacle in the wall

And it is just a receptacle in the wall. Nothing in the appearance of the receptacle suggests, that it is not providing correctly wired 3 phases

Many years from now, a new cooker will be brought in, which excepts proper 3ph connection, and happens to have come from the factory (or was wired according to the instructions) with a Perilex plug in the correct 3 phase configuration. Many of them only really use 2 phases, so it may never be discovered that there is no voltage supplied on the 3rd phase terminal. The current of the 2 load components will sum up and run through just one N pin of the plug - the one which is the proper N. There is your hidden overload....

If, in addition, this is wired with a 5 core (meant for 3 phase) cable in the same scheme, then in addition to the socket pin overload, a conductor in the cable will be overloaded through the entire length of the cable which goes through the entire house

That is only one scenario of mishaps resulting just from this connection method (and there are more), before accounting for the bad quality wiring job too

Ash, this is known as a 'cooking outlet' here and there are different allowed ways to wire it up. It is not miswired according to our (and probably also other western european countries') electrical code.
I mean, it's a fuckup that it was such a shitty job, but the wires were in the correct place.

Most smaller residences (like mine) only have single phase (i have 1x 35a 230v coming into my house). This means in my case, the Perilex is wired to 2 mechanically linked 16a breakers, with 4 wires (2x neutral, 2x phase) + earth going to the outlet. Some call this '2 phase' which is of course wrong - it is 2 coupled single phase circuits.
This is odd, but if you only have 1 phase power in your house, it's either this or have a bigass ceeform outlet and plug in your kitchen, extra heavy and stiff wiring to be pulled through our fairly small conduit etc etc. I think this is the reason why somewhere in the 60s, our country chose for 5 wire Perilex rather than a bigger 32a rated 3 wire circuit. But i don't know. It's speculation. Ceeform is nice but big.


In a larger home you might have 3 phase coming into the house, usually 3x 25a, sometimes 3x 35a. In this case you wire up the Perilex for 3 phase use. And yeah, you can't see how it's wired up from outside, but it's just one of the things you gotta check when you move into a new house. Check what kind of power comes into your house, 1 or 3 phase. No big deal.

On the stove/cooker there will be a big sticker on the plug that indicates how it is currently hooked up. Mine came with a big red tag, impossible to overlook.
Internally there will be a tag board to rewire the thing for 1 or for 3 phase use. I've seen these 'One of my cooker zones does not work' questions on forums on occasion, but it's usually no big deal to get that straightened out.

This standardized use of Perilex for 2x1L + 2xN is something i never knew about - I know about it from you 1st time. So it might indeed be some Netherlands or Europe specific thing which is not universal everywhere

We also use Perilex for cooktops, but only in the 3L configuration. (IEC connectors are sometimes used too for both 3L and 1L, and usually are completely hidden behind the kitchen cupboard, and BS546 is lso used for 1L)

Unfortunately, we do have some "creative minds" who often do stupid stuff when trying to solve problems, including miswiring of equipment in ways that create dangerous situations they dont understand, and somebody who comes years later to do some work doesn't expect

When the cooker is 3 zones then it will indeed be noticable that 1 zone is not working

But many cookers only contain 2 zones in them. With such cooker the user will never know that something is not wired correctly, as everything works normal. However, with 2 16A zones loaded to the max, the current in the N wire will be up to 32A on a single 2.5mm2 conductor and 16A plugf pin

2P 16A breaker, or even a 2x(1P+N) breaker won't help here, as they don't detect current on the N wire. 4P 16A will help, but it enables other types of problems which may lead to more damage

At least it seems that the manufacturers try to label everything clearly, and the setup is common enough that some people can identify it and instruct others

From what I know US switches and sockets are basically made to be disposable, it's just a single piece you can't open without getting destructive. Same with new european things really, it's not made to last.

We're actively using early 1900s material at home and it all works like new, I rewired the house some years ago and also took the time to restore the sockets and switches, they're porcelain pieces with brass contacts inside, so making them tight again only took a little bending using pliers, I also re-polished everything to remove the 120 years of grime they had on them. The switches don't have a clicky spring, it's just a contact that slides over the other, it works like a valve.

I did it because of two things, one to keep the decor period accurate, cheap plastic switches would honestly ruin it, and second because there's no way to install something new without smashing the walls to get new boxes in place, the existing ones aren't compatible with new things, the plastic switches simply don't fit in any way.

You *can* use old things, just not 1990s old. 

That's how many really old switches were done. Incandescent lamps dont make too much arcing, so while there is wear on the contacts, they are just big enough to last 120 years and more. The sweeping motion guarantees clean contact point every time

Here many of the devices made in the 90s were still the good ones, that actually can last

I've been in my disaster of a house for almost 26 years now . I've seen several members who collect old switches and receptacles talk about installing them in their future homes . PLEASE DON'T !!!! In the past year I've had to replace 2 switches and 3 or 4 receptacles . I currently have a couple of seldom used switches that "sizzle" when 1st turned on unless you kinda jiggle the handle !!  The last thing you need is to have your house burn to the ground from a house fire . The replaced receptacles would get warm/hot after use as would the plugs .  The new ones are WAY tighter and are still cool after use .

 If you want to collect this stuff for display , fine but DON'T put it into daily use !

It stands to reason that super worn out old switches would be near EOL. But I am sure NOS  ones would be fine to use. Additionally, I have experienced hundreds of examples of old snap switches and mercury switches that are still functioning fine in institutional buildings and in some of my friends houses.