KEN'S KORNER - The Devil's in the Details
The Devil’s in the Detail
The old saying "The Devil's in the Detail" can be related to almost every aspect of data center planning and execution.
What detail has been the devil for you?
Do you have maintenance outlets in your data center?
If not, you should.
Maintenance outlets are power receptacles that are NOT fed from the UPS and/or RPP/PDU power supply. These maintenance outlets should be fed from a separate, non-critical power source that is NOT powering the critical servers in the data center.
With these maintenance outlets, you ensure that maintenance crews or vendors do not plug a piece of their equipment - power tools, vacuums, oscilloscopes, test meters or attempt to charge a laptop or cell phone - into a critical UPS fed outlet that is inside your server cabinets; and if done could cause an overload that can shut down a server. Also, if the maintenance crew or vendors use faulty equipment, a direct short can occur to the individual branch circuit breaker, if it fails to trip. The next breaker in line, on your main panel breaker, could open and bring down a number of servers in the data center.
Maintenance outlets should be placed on columns, around the perimeter of the room, or even in flush mount outlet boxes in the raised floor. Each outlet should be clearly marked "for maintenance use only". This is an example of an item to add to your raised floor rules so that everyone working in the data center understands the purpose of the outlets.
An example of how severe this can be is a case when a company hired a vendor to clean under their raised floor without having maintenance outlets available for use. The vendor plugged their vacuum cleaner in a power strip located in a server cabinet which had several unused outlets. Then, while putting the raised floor tiles back in place, a tile was dropped on the vacuum cleaner cord, cutting it in half which caused a direct short to the power strip. The cabinet was not dual-corded so when the circuit breaker that fed that power strip tripped, it shut down the entire server cabinet. This would not have happened if a maintenance outlet was used.
Ken Koty