Powerline, ethernet over powerlines question

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I've been thinking about buying a couple of these adapters that allow you to
have an Ethernet network over your powerlines so I can connect a computer in
my garage, 20 ft. from the house, to my main computer in my house, and get
Internet access through it.
Has anyone tried this and had any experience with it? Is it as good as the
ads say it is, or are there problems with it?
Here are one I've been looking at, although I'm not "set" on buying this
brand at this point. http://www.airlink101.com/products/apl8511_22.html
I don't have Ethernet cable wired out to the barn and thought this might be
a way to get around having to wire Ethernet, since the house and barn are
wired together electrically. The barn has a metal roof, and metal back
insulation so I think wireless is not going to work well.
Any thoughts are greatly appreciated.

Re: Powerline, ethernet over powerlines question

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On a typical American home power is supplied by the electrical company using
three wires.  One is a ground, the other two (called "A" and "B" in this
example) are approximately 110 volts each, but with the AC sine wave of
opposite polarity.  This gives you the potential of 220 volts between the
hot lines to power devices needing the higher voltage.  That's why most
American circuit breakers take two slots in a breaker box to support 220
volt devices.

That's all well and good until you try plugging in your power line Ethernet
adaptor into a circuit powered by a breaker or fuse being supplied by say
110 line "A" and your other Ethernet adaptor is being powered by a breaker
or fuse on power line "B".  Unless your electrician has installed a special
bridging capacitor at your circuit breaker or fuse box connecting feed "A"
and "B" together at the radio frequency level the two Ethernet devices will
not be able to establish an Ethernet connection.

If you are lucky and both outlets are being powered by the same hot wire,
either "A" or "B", from the power company transformer then this is not a
problem.  For most people there is only a try-it-and-see methodology in
order to identify how your place is actually wired.  The alternative is to
have an electrician install a special bridging capacitor at the circuit
breaker or fuse box, not something for a do-it-yourself person to try.
Unless you know exactly how your place is really wired it's about 50/50 if
the devices will be able to talk together if they are not being powered by
the same actual circuit breaker or fuse (not the buildings main breaker or

I have seen people use them with no problems and others that never could get
them to work properly.  Assuming the devices are able to even make a
connection (both are on the same power line feed) they are still subject to
possible interference from motorized devices or other devices generating
interference much like wireless devices are.  Again it's almost impossible
to determine in advance if that will be a problem.

If it works out of the box great, if not you may still have other possible
avenues like having a bridging capacitor installed or using a wireless
device that allows you to mount a remote antenna on the outside wall of the
barn.  That is why I always make sure the wireless devices I purchase have
the option to replace the supplied antenna with a better one or attaching a
remote antenna to them.

So my final suggestion is to make sure that what ever device you purchase
comes with a no questions asked (and no restocking fee) return policy.

Re: Powerline, ethernet over powerlines question

GlowingBlueMist wrote:

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a (bridging) capacitor is a simple device easy to fit. But what your US
codes have to say about that I've not a clue.


Re: Powerline, ethernet over powerlines question

Lucky for me, my breaker box has 2 rows of breakers, A & B. I checked this
before I installed some X-10 remote switches in the barn to turn on outside
lights that aren't wired to the house to find what line the barn is on. It
is on line B and the outlets in my computer room are also on line B. The
more I think about it though, I think I'm just gonna run Ethernet cable from
the house to the barn. That will give me the best connection I can get.

Thanks for the reply,

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