Take the 2-minute tour ×
User Experience Stack Exchange is a question and answer site for user experience researchers and experts. It's 100% free, no registration required.

The AC adapters for a lot of equipment seem to be specifically designed to block the AC outlets around it (this is in the US).

Is this a safety feature to minimize the power to that outlet or just lack of common courtesy?

Clarification: I am NOT asking how to "fix" the problem, but why it exists in the first place. Most of the fixes comprise of adding more wires to a problem which I don't understand why it exists in the first place.

share|improve this question
    
Apart from making the adapters smaller, some power bars have the sockets at an angle, this ensures that adjacent sockets are not blocked by such adapters. –  Dhara Mar 3 '13 at 9:53
add comment

7 Answers 7

up vote 9 down vote accepted

The kind of adapter you are referring to is called a wall wart. To quote the article referenced :

One of the major advantages to a wall wart has to do with preventing overheating to both the power source and the device that is receiving the power. Because the wart proper is removed from the equipment that receives the electrical current, it is possible to maintain a proper temperature at both ends of the device. Many models of the wall wart are manufactured with built in thermostats that shut down the unit if a malfunction takes place and the wart begins to overheat.

The wall wart hence has to accommodate for all the components needed to the switching and matching and also accommodate for the transformers size which is required to handle and do the switching. The larger the size of the transformer, the larger and heavier the adapter thus blocking up the surrounding area making it difficult to put in other outlets.

Here are two examples of inbuilt transformers for linear and switching power supplies.

enter image description here enter image description here

That said its pretty bad design and there are a lot of complaints about how the system was initially designed.

share|improve this answer
add comment

It's not as if engineers sat around and designed them to block adjacent plug points. They are large because of the physical size of the components that they need.

With newer technology, and lower power devices, some AC adapters no longer do that, but for larger devices that is likely to be an issue for years to come. enter image description here

One solution is to use a cable extension between the AC outlet and the adaptor. enter image description here

share|improve this answer
    
They have 1' extension cords!? Wow, have I been missing out. –  Cole Johnson Mar 14 at 0:05
add comment

Another solution (along the lines of @JohnGB's answer but with no supplemental cables needed) is to use a newer type of power strip that can accommodate large AC adaptors without blocking other outlets. One novel design is the Quirky PowerPivot that bends not only to accommodate large power "bricks" but also to fit in your space neatly:

Quirk PowerPivot

share|improve this answer
add comment

IMO they are not designed, just engineered. With due respect for engineering, which is a must. Design seems to be considered optional.
There is no need to limit the current from the output, as most such devices handle low power levels, if compared to an iron or a room heater.

Since some time ago I see bricks without a transformer, the component that made the old ones heavy and bulky. Modern power supplies are smaller, lighter and colder.
But yes, even the smallest, like my cellphone charger, will interfere with the adjacent connections in a power stripe.

share|improve this answer
add comment

There is a cost involved in designing things in ways that changes basic engineering. Printed circuit boards for a long time (and probably still) were easiest to layout and cheapest to purchase if rectangular. Components are laid out on PCB's according to engineering needs. For example, the placement of heat sinks for optimal cooling. Plastic housings can be purchased in bulk with little customization. So I think most companies rightly did not invest their money in redefining the adapter. Of course, laptops changed that because you need to carry the adapter with you.

share|improve this answer
add comment

Firstly, this hindrance is not true of all adapters. Transformer-based adapters take up space because they contain a large transformer. Switching supplies can be fit into a much smaller space. For instance look at the current crop of cell phone chargers.

Secondly, even transformer adapters are small enough that they can be plugged into a two-socket outlet along side with another appliance or another such adapter. Where they become a hindrance is power bars. This is due to the arguably bad design of a power bar, which stacks the outlets vertically, without space in between, failing to anticipate that users have numerous adapters.

The fix is to design a power bar whose outlets are on a 90 degree angle and have surrounding space.

Look at this power bar. It has an outlet with extra space around it which accomodates one wall-wart, and the outlets are at 90 degrees:

dusty powerbar

The tranformer-based wall-wart shown is more than a decade old, yet compact. Two of them could fit into two-socket outlet, and this is by deliberate design. In other words, the engineers took steps to ensure quite the opposite of what you're suggesting, by placing the prongs close to the edge of the box.

Of course, you cannot place N of these warts into a conventional N socket power bar. This is simply not possible due to the size of the transformer.

Also shown in the picture is a modern cell phone power adapter, which is not much larger than a passive plug. Its power handling is about the same as that of the other adapter.

Now here is one more shot, which contrasts two transformer-based adapters. The large one is late 1980's Yamaha unit. It has to be that way because it's robust. This thing runs quite hot, and still works after 25 years of use.

The small wall-wart is also transformer-based (I believe) rather than switching, and shows you that these things can get down to size. However, it is only rated for 200 mA at 9V. A switching supply in that size can deliver a lot more current.

Large as it is, the Yamaha one can still be plugged into a two-socket wall outlet, while that outlet accommodates another appliance. Again, it's designed for minimum hindrance, while providing the necessary space for the transformer and ventilation around it. Note how the tiny wart, and the big one, both have just about exactly the same clearance between the prongs and the closest edge.

Back of a music rack

Here are two of these power supplies easily plugged into the same outlet, with half an inch of clearance in between!

enter image description here

So basically, your premise that engineers deliberately design adapters to hinder other devices from being plugged in is wrong; you just have to think about your adapters when you're shopping for a power bar.

share|improve this answer
add comment

Wall warts sometimes block adjacent AC outlets, not because they were designed this way, but because it's easier and cheaper to make a product with an external power supply. Usually the wall-warts are provided by Chinese manufacturers as a turn-key solution for other companies, at ultra-low cost.

It is not always feasible to do an internal power supply, because it takes a lot of time & money to develop. There are also size considerations, because the main components of a power supply usually involve physically large capacitors and a transformer, so it could add bulk to a product.

Take for example, the AppleTV. Apple did care enough about this design consideration to spend its time & money creating an internal power supply. Roku, on the other hand, being a much smaller company, has an external power supply. However, at least Roku has enough consideration to make their wall-wart expand horizontally, so to not block another vertical outlet.

AppleTVRoku

There is a 3rd option, which is to do a "line-lump", where the power supply is separated from the plug, so it also solves the problem of blocking outlets. A neat example of line-lump is Apple's power supply for its MacBooks. The design gives the user the option of either have a wall-wart or a line-lump. Even in wall-wart mode, it does not block the other outlets.

Macbook power supply

share|improve this answer
    
Just because it's external doesn't mean it has to be at the outlet. My laptop cord (and a lot of others) have the transformer halfway down the cord. The Nintendo 64 put it on the end of the cord that goes into the N64. –  Cole Johnson Mar 14 at 0:07
    
I talk about "line-lumps" in my answer (See the Macbook power supply) –  kwahn Mar 14 at 21:27
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.