Deployment of UPS Systems With Rear Mounted Receptacles

Here at National Power Corporation (NPC) we occasionally see custom orders that add rear-mounted receptacles. The Ferrups, 9PXM, and 9155 are in the category of solutions with this custom capability. But are rear mounted receptacles the best solution for your customer?

The benefits of rear mounted receptacles are:

There is a disadvantage of rear mounted receptacles. This custom feature eliminates the option to utilize an external maintenance bypass panel (MBP). An external MBP provides a wraparound path for power which gives the user the ability to completely remove power to the UPS while maintaining power to the critical load. This capability allows the end user to perform two important functions without shutting down the loads:

Utilizing an external MBP in a rear mounted distribution application would negate the advantages of the MBP since activating the MBP feature will remove the loads to the UPS and any loads plugged into the UPS.

The question becomes, “Are the advantages of an external MBP significant enough to overcome the additional costs for utilizing wall mounted distribution?” There is no clear answer as each site will differ, each customer’s needs will vary. The best approach may be to educate your customer and let them make the decision. Some of the topics of discussion to have with the customer would include:

It is the opinion of NPC that all sites should have an external MBP when possible. The discussion for deploying a UPS should always include this device until conditions dictate that an internal MBP option will suffice or no bypass option is needed for the application.

If your customer is on the fence about whether or not an external MBP is required you can share with them this thought. In my 37 years in the UPS industry, I have yet to hear of a customer that regretted installing an external MBP, but I have heard many regret not installing such a device.