Home / server / Questions / 77580
In Process
Gavin Brown
Asked: 2009-10-24 02:32:34 +0800 CST

Securing power cables

  • 772

It's always annoyed me that while the sockets for network, serial, parallel and display cables all have securing mechanisms (ie a screw-in bolt, or a clasp) to stop them from being pulled out by jostling, there's nothing similar on power sockets (ie IEC 60320 C13 and C14 connectors). It seems to me that while accidentally knocking out a server's network cable is bad, it's nothing like as bad as accidentally knocking out its power.

Using power distribution units/UPS systems actually increases the risk of this happening because you then have two poorly secured sockets per machine, rather than one.

Is there any reliable, standards-compliant and relatively cheap way of securing C13/C14 connectors? I'm thinking about the sort of thing I can epoxy on the back of the servers that will hold the power cable securely. Are there any manufacturers who build something like this into their chassis?

electrical-power

6 Answers

  1. There is at least one solution - IEC Lock - that I'm aware of. I think it's based on some kind of spring-friction mechanism and fits existing sockets. I haven't personally seen the need to try any locking solutions, so YMMV.

    Places selling those can be found e.g. searching with Google. Prices are around 3-4 USD, so I'd say it's relatively cheap.

    • 9

  2. Every rack mount server I have purchased in the last 5 years, has came with power cable strain relief clips of some kind. If properly used it would take a lot of force to pull the power cable.

    • 4

  3. Enterprise class servers and PDUs have them built-in already! :-)

    • 2

  4. I have used Panduit cable-tie anchors for this sort of thing. They have small "loops" through which you pass a cable tie and are backed with adhesive to stick to the chassis.

    I use mostly IBM servers and they have various methods of anchoring the power cable. NetApp filers are the same way, as are Juniper switches and I think routers.

    • 1

  5. If I really don't want a plug to be accidentally removed from a power strip, at least the type where you have access all the way around it, I use either one long or two shorter cable ties. Wrap them around the power strip and the upper part of the plug in a figure-8 fashion.

    • 1

  6. We use APC racks, UPSes, and PDUs. UPSes are hard-wired. Connection from the UPS to the PDU is with a twist-lock cord (L5-20 or L5-30).

    For the last hop of the power connection (C13-C14, which seems to be what you are asking about), we use these special locking power cords from APC.

    • They positively "snap" into the socket, so they can't accidentally pop out of the PDU.

    • On the server/device side, the cords have a little "bump" that provides some friction to hold the cord in the socket. Not a positive lock, but it still helps.

    If your power infrastructure is APC, I highly recommend them.

    Note that you only see the benefit using the APC cords with an APC PDU. The APC PDU still accepts normal power cords.

    Also, wherever possible, we try to use some form of strain relief on the server/device side. See if you can Zip tie power cords against the back of the server so they are not taut.

    Other things you should be doing:

    1. Redundant power feeds on any device that supports it. Most servers and critical devices should have 2 power cords, each going to a separate PDU. (Plugging them into the same PDU won't help you when the PDU fails, or you unplug it accidentally.)

    2. For devices that do not redundant power supplies (network switches), you should have redundant devices. Each device should be plugged into a different PDU.

    3. If you are using the dual PDU approach, make sure each PDU is <50% loaded so it won't trip when the partner PDU gets unplugged accidentally. (Metered PDUs are helpful here.)

    4. Ideally each PDU should be connected to a separate UPS. UPSes can and do fail. People also accidentally turn off a UPS. Again, make sure each UPS is sized to handle the load if its partner goes offline.

    5. If two UPSes is not feasible for your facility (due to size, cost, etc), at a minimum you should be using UPS with redundant power modules and batteries.

    6. You can take the power redundancy a even further. If you have dual UPSes, you can have two power feeds into your building (from two separate power companies). Generators of course!

    • 0