Questions[power-distribution-unit](server)

I removed the side panel of our server rack so I can clean up some of the wiring. Inside I found the PDU was wired like in the picture. Instead of an incoming power cable, there's just 3 uninsulated spade connectors.

Is there any reason for wiring it like this instead of using a C19 to appropriate connector for your country cable?

Or did whoever do this just not have the right cable handy, and figure this is good enough?

Edit:

When I say uninsulated, the metal parts of the spade connectors do look completely bare. I haven't looked too closely to see if there's clear insulation or something, but it doesn't look like it, and it's live.

Edit 2

Proper cables are being dropshipped and will be installed as soon as they arrive. In the mean time nobody is going to go anywhere near it. I can easily cut power to the PDU so replacement wont be a problem.

Edit 3

The cable to the PDU has been replaced with a proper one. No electrician needed. No fires, no injuries. Yay! The faulty cable has been destroyed so nobody ever gets tempted to do something like that again. For extra damage, the cord they attached those spades to was only an 18 gauge cable, not the 14 gauge ones usually used for servers.

I just chatted with an APC rep about upgrading the UPSes at our office. She recommended a single higher-capacity 6-outlet Smart-UPS to replace the four Back-UPS units we currently have. When I asked how she recommended plugging in all the current devices, she recommended using a APC's AP9567 PDU, but said not to use a power strip. At first she said I had to use an APC brand PDU, but after I inquired about using a Tripp-Lite PDU, she said any brand PDU would be fine.

The APC PDU previously referenced looks like a standard 120V power strip with overload protection but no surge protection. Other than overload protection (which seems redundant if plugging into the UPS), is there something else I'm missing, or should any power strip (without surge protection) be fine?

Edit: I didn't mention it earlier, but we don't have a proper rack--though I did still plan to mount the PDU or power strip to something. I guess I'm wondering if there's any special reason I should pay as much as $180 for the low-end APC PDU (which just looks like a power strip to me) vs. $20-$30 for a workbench power strip.

I've struggled with sizing my power sources and associated PDU's in my server racks. Somehow I feel like I'm way oversizing things based on nameplate requirements on power supplies.

My simplistic approach is to look at the nameplate draw on my power supplies, add them up and size my feed for that. Doing that with a rack that has 10 servers, 1 storage array, and 4 Cisco Switches leaves me with 6 - 20 amp circuits? How do I arrive at this figure? Well, I look at absolute worst case which in my mind is half of my power supplies have failed and I'm starting up all my equipment at the same time on 3 circuits connected to the half of the power supplies remaining. Because I have to assume all load will be concentrated on half of my outlets that effectively doubles my requirements.

Does anyone have a better methodology than this? My customers freak a little bit when I tell them I need 80 or 90 amps for 8 or 9 servers and some switches. It does sound a little over the top. I know one option might be to configure the high draw equipment (like servers and arrays) to not power on when power is restored. I don't know if I have an option to delay power on either. That would be nice. Do switched PDU's have a feature like this where it will stage the outlet power ons. That seems like it would be effective.

Clarification

I know I can use the calculators to determine steady state power draws which are much lower than the startup power draw. My ultimate concern is startup power draw for all components at once. From there I effectively have to double the amount of capacity I deliver to the cabinet to account for starting up on only half of the available capacity because half of my power supplies are failed.

Based on some research it appears switched outlets that can stage themselves might be the answer. Others agree or have better solutions?

With network cables it is easy. I use velcro-ties, coloured cables, 0U vertical cable organizers from APC on side of the rack -- easy and neat.

However with power cables it was always giving me headaches.

With some of the racks I am using Vertical PDUs from APC (0U) so it's kind of neat as am getting 0.3m/0.5m cables and connecting them to servers which are close to the PDU sockets. It's kind of neat, but it could be better.

With horizontal PDUs it is really bad -- no matter how hard I try there is always few cables that are too long and are hanging loose below the APC.

Eg. http://www.flickr.com/photos/92011471@N00/25695150/ -- this will cause the cables on the bottom to be different length and its going to get quite messy...

What are best practices for power cabling? How do you guys do this so your cables once put in once are neat and you don't have to worry about them for years? Do you also cut them to match right length? Do you use some special organizers? Or maybe you know some tricks like hiding them between the side of the server and rack?

I went through many many posts on SF however most of the are oriented around network cabling and very few are touching slightly on the power problem.

Of course I am talking about having network cables on one side and power cables on the other side.

Any suggestions, recommendations, suggestions much appreciated.

I have some racks that will be fed by 208V/20A circuits. These circuits will be conditioned and battery-backed by the facility in which these racks will live. 99% of the devices in the rack will be able to support 208V input, so I plan to use these PDUs.

However, there may be one or two odd devices that will need 110V input. I know that I can use a step-down transformer to provide 110V for these devices, but that seems like overkill for such a small number of devices, plus I don't want to pay extra for the UPS functionality since my power will already be battery-backed.

Any suggestions for something I can use for these one-off 110V devices?