What is the difference between a PDU and a power strip (both 120V, 15A)?

Question

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.

Solution 1

In addition to amcnabb's answer, higher-end PDUs (though not the one you linked to) will also give you the possibility of not only monitoring (over the network) the current draw for each socket, but also cutting and restoring power to certain sockets remotely.

Solution 2

A PDU will mount nicely to a rack, while a power strip is likely to get pushed around. It's mostly a matter of convenience, but in theory a power strip wiggling around could make a safety or reliability issue.

Solution 3

I found this from APC's FAQs: Using surge strips with APC's Back-UPS and Smart-UPS products. Looks like a PDU is a bit different than a regular power strip.

Surge protectors filter the power for surges and offer EMI/RFI filtering but do not efficiently distribute the power, meaning that some equipment may be deprived of the necessary amperage it requires to run properly causing your attached equipment (computer, monitor, etc) to shutdown or reboot. If you need to supply additional receptacles on the output of your UPS, we recommend using Power Distribution Units (PDU's). PDUs evenly distribute the amperage among the outlets, while the UPS will filter the power and provide surge protection. PDUs use and distribute the available amperage more efficiently, allowing your equipment to receive the best available power to maintain operation.

Comments

[Joe]

I really like side-mounted (vertical) PDUs instead of horizontal units, as they generally don't take up any rack-space that would otherwise be filled with servers. Additionally, any equipment damage protection reimbursement that APC may be providing (in case of power-related issues/damage) will probably not be honored if you don't use rated PDUs.

[rob]

That sounds like a really handy feature!

[EEAA]

Yes, it is very handy, especially when it's difficult to get your hands on the physical hardware (such as in a colo environment).

[rob]

@Joe: what constitutes rated in this case? If I can buy a workbench power strip with the same or better electrical ratings (125V, 15A, 1875W, overload protection) for a lot less, what distinguishes a low-end PDU from that? Is there a particular certification I should be looking for?

[rob]

Joe brought up a good point regarding "rated PDUs" in a comment on amcnabb's answer, but I'm still not clear on what differentiates a low-end PDU from a power strip like the one I linked to in my question. Is there a certain standard or certification required, or is it safe to assume that any power strip with the same or better specs than the APC PDU (125V, 15A, 1875W, overload protection) can also be called a PDU?

[EEAA]

@rob - discounting network monitoring features and sane rackmount compatibility, then yes, PDUs are essentially power strips.

[rob]

thanks for confirming my hunch. In that case, is it likely that APC (or another UPS vendor that allows the use of PDUs) could legitimately deny a warranty claim if I use a power strip that is at least on par with the vendor's entry-level PDU?

[EEAA]

@rob - no idea. That's something you'll need to take up with APC. That said, cheaping out on this type of gear will, sooner or later, bite you in the ass every time.

[rob]

Okay, I guess this brings us full-circle and I can try asking again. :) The first time I asked, they said that it must be a PDU, not a power strip--but as far as I can tell, there is absolutely nothing to distinguish a low-end PDU from an equivalently-spec'd power strip, electrically speaking, so it doesn't seem like they should be able to legitimately deny a warranty claim. This might be more an academic question than a practical one at this point, since I also just found some PDUs on eBay in the same price range as the power strip.

[MooseBoys]

I know this is an old answer but it's the top search result on stack exchange for "PDU vs Powrer Strip" queries. What does it actually mean to "distribute amperage more efficiently"? Power strips put line, neutral, and ground each on a shared conductor. How can you get more "efficient" than that? Are they claiming that if the total current draw is more than the supply can deliver, it'll cut off a specific outlet vs. undervolt all of them? If you never have that condition, is there no practical difference?