Maybe Some Alternatives as well (adding on to the title) 
Here's what I mean:
Let's say you have a device that takes a 12V DC adapter with a current of 500mA and the device states "only use the adapter that came with it". But then you realize that many 12V DC adapters have a current of 500mA and you just use a random 12V adapter.

You have a light socket rated for 13W CFLs only, but why is that a thing, I understand with Inc. but CFL? Anyway you use a 26W CFL and it works fine.

That's all I have for now, lets see what you can come up with.

For adapters, it is a question of liability. The manufacturer of whatever device it is wants to cover up their you-know-what in case of possible lawsuits, etc. They have tested their adapter and know the tolerances, which fall within the tolerances accepted by the device. That way, it's a case of 'I told you so' if ever you bring in the broken device and you used another adapter. If you use another one, you'll probably be fine, but the manufacturer wants to be sure...

Now for lamp sockets, you have to be within certain specs. The lamp holder might be good up to 200W incandescent, but the insulation in the fixture or the lamp shade might not. It can be a fire hazard. With externally ballasted lamps, you have to match the lamp to it otherwise it won't work (or not very well). You might just end up with overheated components and in extreme cases, a fire.

If you use something other than the recommended, make carefully considered, educated choices. Research the effects before. Otherwise, I told you so. 

With the externally ballasted CFLs there are two compatibility problems: Overheating (either the lamp itself or the fixture) and/or electrical supply.
The overheating means if you put there different lamp, the fixture may overheat and degrade (yellowing, getting "crispy",...) and/or the lamp may operate too hot or too cold and so exhibit worse performance. Unlike the incandescents, the fluorescents are quite sensitive on the temperature of their "cold spot". That is the place, where the mercury reserve is located (with modern amalgam lamps it does not have to be really the coldest spots, amalgams tend to dictate lower pressures on higher temperatures, therefore are used on the hotter running modern high intensity fluorescents) and whose temperature then dictates the mercury vapor pressure within the lamp. The lamp needs the pressure to be correct, otherwise the output, so efficacy drops significantly. The modern amalgam lamps are less sensitive, but still the temperature does matter.

The electrical mismatch is more difficult, because it becomes quite difficult to get the exact electrical parameters the lamp needs. The power rating is generally useless for matching lamps vs ballasts. You need to know mainly the arc current (that is the key parameter, equivalent to the "220V" mains or "12V" adapter specification) and then the lamp arc voltage (this is secondary, like the "500mA" on your DC adapter).
In other words the lamp will most likely work if the current matches even when the rated power differs and it won't work if the current will be too off even when the power rating appear to match.

The arc voltage is important to asses, if the ballast or its components won't be overloaded.
Here is important to differ the way, how the ballast works. Some ballasts types get more loaded with lower arc voltage and less loading with higher arc voltages (e.g. a series reactance, NPF HX autotransformers,...), some other topologies behave exactly opposite, so lower arc voltage is OK and higher is overloading them (many electronic, HPF transformer type ballasts,...).
Generally it is way more complex, so there are way fewer combination which are able to operate well other than the rated ones.

All you need to do is use your common sense about what to put in the fitting...
The only problem is that common sense isn't all that common... 

All you need to do is use your common sense about what to put in the fitting...
The only problem is that common sense isn't all that common... 

Sadly true 

If you ever need to get a replacement device such as a phone charger, my recommendation is ALWAYS use the manufacturer's original, even if it's more expensive. The cheap crap (usually, but not always, Chinese) that floods the market these days are not fit for purpose and may well cause a fire. We saw a programme on TV the other day where someone had a very narrow escape when their replacement charger burst into flames while they were momentarily out of the room.

Very inexpensive chargers are a known fire hazard. A school principal in my area lost his house last summer to one such charger. The house is not near  nor far from the neighbours, and they were away when it happened. It took quite some time for someone to notice (it happened at night) and being in a rural area, it took too long for the volunteer fire fighters to arrive. The only thing "salvageable" is the piece of land.

Now, a nice, quality, heavy, low heat magnetic ballast can catch fire as well, but the chances are way lower than a piece of electronic that is probably in a too small enclosure with inadequate parts certainly has higher odds of catastrophic failure...

Very inexpensive chargers are a known fire hazard. A school principal in my area lost his house last summer to one such charger. The house is not near  nor far from the neighbours, and they were away when it happened. It took quite some time for someone to notice (it happened at night) and being in a rural area, it took too long for the volunteer fire fighters to arrive. The only thing "salvageable" is the piece of land.

Now, a nice, quality, heavy, low heat magnetic ballast can catch fire as well, but the chances are way lower than a piece of electronic that is probably in a too small enclosure with inadequate parts certainly has higher odds of catastrophic failure...

That's not something I would want to happen with us, before going away we make sure that all non essential electrical appliances are switched off at the mains.

That's not something I would want to happen with us, before going away we make sure that all non essential electrical appliances are switched off at the mains.

We do that but in a different way. The way we do that is by unplugging all power strips (If accessible) or we just turn it off.
Mostly everything is plugged into a power strip, of course excluding kitchen app.

We do that but in a different way. The way we do that is by unplugging all power strips (If accessible) or we just turn it off.
Mostly everything is plugged into a power strip, of course excluding kitchen app.

All of our sockets are switched ones, and it is there that we switch off rather than at the main breaker. Some of our power strips have individually switched sockets as well.

But it is not a good idea to use the circuit breaker as a regularly used switch (here it is even prohibited by the code to install the breaker for that use, a separate switch is mandatory if the circuit is to be switched ON/OFF regularly).
The reason is the breaker used as a switch will very likely mechanically wear off and then the protection functionality becomes questionable (and in that way using breakers to switch off appliances is increasing the fire danger instead of reducing it).

Otherwise my experience with electronic vs magnetic regarding the fire danger is rather opposite: The heavy iron takes long time to heat up, but then to cool down as well, so once it exhibits a thermal runaway failure (winding gradually shorting turns), the scorching hot heavy brick becomes quite potent to set a lot of things on fire even way long minutes after the breaker switched it off.
On the other hand the electronic usually contains small, very low mass sensitive components, which become hot within fraction a second upon a catastrophic failure, but then trip either the fuse or breaker at the same speed, so afterwards cool down way before they reach anything flammable.

Of course, you may have fire starters from any device if it is designed or used improperly, regardless if it is the heavy "iron&copper" or some "silicon sand". The "silicon sand" has just inherently a bit more odds to fail without other consequences...

But it is not a good idea to use the circuit breaker as a regularly used switch (here it is even prohibited by the code to install the breaker for that use, a separate switch is mandatory if the circuit is to be switched ON/OFF regularly).
The reason is the breaker used as a switch will very likely mechanically wear off and then the protection functionality becomes questionable (and in that way using breakers to switch off appliances is increasing the fire danger instead of reducing it).

Otherwise my experience with electronic vs magnetic regarding the fire danger is rather opposite: The heavy iron takes long time to heat up, but then to cool down as well, so once it exhibits a thermal runaway failure (winding gradually shorting turns), the scorching hot heavy brick becomes quite potent to set a lot of things on fire even way long minutes after the breaker switched it off.
On the other hand the electronic usually contains small, very low mass sensitive components, which become hot within fraction a second upon a catastrophic failure, but then trip either the fuse or breaker at the same speed, so afterwards cool down way before they reach anything flammable.

Of course, you may have fire starters from any device if it is designed or used improperly, regardless if it is the heavy "iron&copper" or some "silicon sand". The "silicon sand" has just inherently a bit more odds to fail without other consequences...

We don't use the breaker to switch off appliances, I was just saying that to to clarify the 'switching off at the mains' statement. 

I believe some large commercial HID and fluorescent lighting installs in North America are only switched at the panel with switch duty breakers instead of using a lighting contactor. The NEC allows it as long as the breakers are rated for switching and are marked with a SWD or HID marking.

    NEC 2011
    404.11 Circuit Breakers as Switches. A hand-operable circuit breaker equipped with a lever or handle, or a power-operated circuit breaker capable of being opened by hand in the event of a power failure, shall be permitted to serve as a switch if it has the required number of poles.

    Informational Note: See the provisions contained in 240.81 and 240.83.

    240.81 Indicating. Circuit breakers shall clearly indicate whether they are in the open “off” or closed “on” position. Where circuit breaker handles are operated vertically rather than rotationally or horizontally, the “up” position of the handle shall be the “on” position.

    240.83 Marking. (D) Used as Switches. Circuit breakers used as switches in 120-volt and 277-volt fluorescent lighting circuits shall be listed and shall be marked SWD or HID. Circuit breakers used as switches in high-intensity discharge lighting circuits shall be listed and shall be marked as HID.

According to UL the SWD and HID ratings are suitable for switching fluorescent and HID respectively loads on a regular basis. I'd imagine some sort of endurance testing is performed to ensure the breakers will trip properly within the rated number of switch cycles.

We don't use the breaker to switch off appliances, I was just saying that to to clarify the 'switching off at the mains' statement. 

It was not meant against your statements, It just reminded me of some people using the breakers as switches, so I wrote it to prevent anyone who gets that "idea" too from doing that...
:-)

For the "large installations":
Many of these are permanent ON, so are not switched OFF at all except of servicing.
Because normally they are all the time ON, they do not need a switch, for maintenance disconnect the breaker is OK.

From the late 1950's to the mid 1990's, it was fairly common for medium installations to have the breaker panel as a switch bank for lighting. Examples are gymnasiums, stores, indoor pools, indoor skating rinks and churches. They are regularly switched, sometimes a few times a day. Some are for incandescent, fluorescent, HID, and now LED. I would imagine the later installations have switch-duty breakers. I know of several such installations still in use today.

Nowadays, newly built such installations are 347V here in Canada, and they have low voltage relays for switching. I have never seen breakers used for lighting on systems other than 120V.

I'm not saying those 40-50 year old installations still in use have perfectly functioning breakers that would trip should a fault occur, however. Maybe that is another reason for individually fused luminaries.

Going back to the question of using the adaptor that comes with the equipment, we have a box full of 'power bricks' and just pull out one with the correct rating if we no longer have the original one for some reason, or if the equipment never came with one in the first place.