For 120v I'm using Web Power Switch and Ethernet Power Controller II from
http://www.digital-loggers.com/For 240v I'm using an APC 7911A.
These are all switched/metered. You'll save a bundle if you don't need management features.
OP, you mentioned PDU. For 20 OC'd antminers, you're going to need PDUs - plural.
APC 7911A is 20 outlets...for about $650 & change...
![Grin](https://bitcointalk.org/Smileys/default/grin.gif)
I just bought APC 7571A ...10 outlets ...for $99 ...
![Wink](https://bitcointalk.org/Smileys/default/wink.gif)
Both are 208V ...
ZiG
Edit : I have 10 Ants S1...you will need 2 of these...