[TriLUG] OT: electricity and networks (a network question, really)

Jeff Jackowski jeffj1 at hiwaay.net
Tue May 13 12:22:41 EDT 2003


On Mon, 12 May 2003, Greg Brown wrote:

>Ether over power seems to be limited to 14 meg/sec, which is okay if 
>all you are doing is 802.11b which is 11 meg anyway. 

I did some research on this recently. According to people who have done
performance testing of this HomePlug stuff, the average speed you can
expect is around 3.5 to 4.0 Mbps. One tester tried to isolate to power
line nodes from any other noise on the AC line and used short cables, but
still couldn't get a data rate faster than 4Mbps. The companies do claim
14Mbps, but then the 11Mbps rate of 802.11b includes a notably larger
overhead than 802.3u (100Mbps Ethernet), so you're not going to see 11Mbps
transfer rates with FTP.

>Now, my question is how far does the ether signal travel over the power 
>cable?  If this type of thing works as claimed then the ether signal 
>must hit the main breaker panel in the house (it has to if it's going 
>from one circuit to another) and if it hits that panel does it 
>propagate out via the main power circuit to the house then possibly to 
>the neighbors houses?  I would imagine that the signal is fairly 
>limited in distance but if you've got a 200 amp circuit coming into the 
>house that copper has to be of fairly large gauge which would allow the 
>signal to travel farther (kind of like 10-base-5 vs 10-base-2 (or 
>10-b-t for that matter)).  And if you can blast 14 meg over 15 amp 
>wires how far can you shoot a signal down a 200 amp wire?



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