Milne Computer Center UPS Information
Circuit Breaker listings
Note: Please contact Andy Morgan before any UPS circuit changes are made so that this
documentation can be kept up to date.
Current draw for common servers
Note: These are a little on the high side, so you should feel safe using these as guidelines
||Steady State Current
|Dell PowerEdge 2550
|Dell PowerEdge 4300
In general, each Dell rack should have two 20A UPS circuits assigned to it. Dell provided PDUs have a 16A
rating, so two circuits with two Dell PDUs will provide a total of 32A per rack. However, only 80% of the
available capacity should be used, to allow for current spikes during initial power-up of servers. This
leaves approximately 26A for steady state current draw.
A 42U Dell rack will physically hold at most 6 PowerEdge 4300 servers, drawing a total of 6 * 2.5A = 15A,
well within the 26A recommended maximum. However, only 13 PowerEdge 2550 servers can be placed in a 42U
Dell rack and still keep the current draw below 26A (26A / 2.0A = 13), although the rack is physically
capable of holding 21 PowerEdge 2550 servers.