Rack Power Distribution & PDU Success Cookbook

This guide is meant to provide some simple recommendations to quickly solve at least 95% of your problems with physical infrastructure.

Here is the cookbook in case you don’t want to read all the details:

For Hooking Your Laptop Up In Your Cabinet:

(Power Adaptor): https://www.amazon.com/gp/product/B073JZ94QD?pf_rd_r=VEHAYA2GW2NK350MFP7A&pf_rd_p=edaba0ee-c2fe-4124-9f5d-b31d6b1bfbee

(Your Best Friend In A Cabinet Setup): https://patchbox.com/setup-exe

Lets get granular. This stuff isn’t rocket science, if you spent as much time as I have exposed to the nuts and bolts of data centers, you could learn it too. The reality is most IT staff are focused on and exposed to higher value and higher level activities such as network engineering and application management, but they still are the ones that end up having to touch this stuff every now and then. Unfortunately, power systems and cabling are distinctly different disciplines than the daily focus of IT professionals. Just like anything in life, having the right tools for the job is extremely important and can make or break the success of your project. A $250,000 storage appliance can be brought to it’s knees by a humble power cable. Even with cloud and other elements, these problems will still crop up in your path as an IT professional, for example at the edge.. so its good to know.

If you really don’t want to ever touch it and really hit the easy button – check out our Colo+ service which provides the worlds best fully managed Colocation where we take care of all physical aspects of the datacenter for you.

The Don’ts

I see all types of PDU’s come into our data centers. I have even seen, despite my pleas, a customer hook two of these up to their A&B Feeds:

While we are on the topic of power strips, DO NOT EVER HOOK THESE UP TO YOUR PDU’s. Many customers make the mistake of doing this in their 208V cabinets with a cable adapter and end up blowing their power strip and tripping one of the redundant feeds to their cabinets. I have even seen a customer trip an A Feed, then unplug the blown power strip and plug it into his redundant power feed, thereby taking his entire cabinet down! Do not do it. If you look on the back of these types of power strips, you will see that they are mostly not rated for 208V power, 120V only.

Where do I plug in my laptop then when I am working?

A question I often get from customers is how to hook their laptop up and accommodate that either short term or long term while working in their cabinet. I have two product recommendations for this, beyond our amenities such as crash carts.

1. Get a C14 plug adapter : https://www.amazon.com/gp/product/B073JZ94QD?pf_rd_r=VEHAYA2GW2NK350MFP7A&pf_rd_p=edaba0ee-c2fe-4124-9f5d-b31d6b1bfbee

These little guys can be handy, but buyer beware, they also open you up to a world of trouble. Make sure you are only plugging equipment that can accept the voltage you are providing into these. >99% of laptops accept 208V, you can check your “brick” if you are unsure to make sure its in the range. The only trouble I have seen customers get in with this is hooking a noncompatible power strip up to these and blowing their strips. Don’t do that – if you need multiple power feeds, consider using multiple C14 plug adapters or running an extension cable to “House Power” (A wall outlet that is 120V) nearby.

2. Get a setup.exe from Patchbox: https://patchbox.com/setup-exe
You will hear me talk about these guys often, and there is a reason why – they are the hottest cabling and cabinet ergonomics creator on the market. This thing acts like a third hand for you which has a million uses, one of which is hooking it in backwards into your cabinet and placing your laptop on it for a comfortable experience. We use them for safely mounting switches, for setting laptops on, for mounting patch panels, as an extra catch safety for mounting servers…the list goes on. Just go buy one, you will thank me later.

The War Against 120V PDU’s

I am raising the flag now. 120V PDU’s almost exclusively utilize NEMA 5-15 Plugs. That’s the same stuff that the lamp in your house uses. It just isn’t appropriate for enterprise equipment, and has no way to additionally secure the plugs to protect against accidentally dislodging them while working in the cabinet or them falling out on their own from the weight of the cable over time. I have seen plenty example of this.

Don’t get me wrong, I have nothing against 120V itself as a voltage. As a matter of fact, I have reached out to many PDU manufacturers and engineers to be told that “The class of client that is looking for 120V PDU’s does not care about premium features such as this” (This referring to locking C13 / C14 plugs and receptacles). In other words, it was very difficult to even FIND a manufacturer that has C14 options available for 120V PDU’s. Due to this reason, I generally recommend that customers utilize a 208V PDU, which we offer sizes as small as 10A 208V for our half cabinets. If this is still too much, then you may look at downgrading to a smaller 120V circuit, such as a 10A 120V.

We did manage to locate a PDU that provides secure C14 receptacles, but is missing a few of the other bells and whistles. We will talk about that momentarily.

C14? Who cares? Those can fall out too.

Most power cables are sensitive to becoming dislodged especially is jostled in any way shape or form. This is where one PDU manufacturer rises above the rest in my mind. Vertiv recently acquired the PDU manufacturer Geist, and they are an outstanding PDU manufacturer. Even this great PDU manufacturer can offer a very broad variety of makes builds and models however so we will get to WHICH PDU’s are the best shortly. Geist rose to the top of the list because of this one single feature however: U Lock Receptacles:

Once you plug a power cable into these, the U Lock holds it in place. You can yank on the cable, pull on it, the U Lock will not let go until you depress the U lock and then pull simultaneously. This is an incredible product and is a game changer for making it feel safe to enter a live production cabinet. This only solves half of the problem though, what about the other end going into the computers? I have also seen these become dislodged.

Enter the “Secure Sleeves” from Stay Online: https://www.stayonline.com/category/i-securesleeves.asp

These sleeves cost $0.50 – 50 cents! Do yourself a favor and buy a big bag and use them. They also have adapters for the receptacle end in case you do not have the luxury of a U LOCK type PDU. With these inserted, it requires a thirty pound pulling force to dislodge the cable which essentially eliminates the chances of an accidental removal of the power cable. This is an absolute must buy cheap accessory and trivializes the risk of accidental power failures inside cabinets. You should also check these guys out (Stayonline) for their custom length power cables ( https://www.stayonline.com/category/c-c14-c18-data-center-cords.asp ) as well as their rack nut installation tool which changed my life: ( https://www.stayonline.com/data-cable-rack/installation-tools-2725.asp )

The Best 208V PDU:

There is more to a good PDU than just a U Lock. Other important considerations that we evaluated for a PDU is remote reboot capability (switched ports), port density for clean cabling (so you aren’t running cables vertically – tip: the more you can cable horizontally the better), and a good ecosystem of peripheral sensors, and ease/stability of installation in cabinets. Vertiv just knocks it out of the park on all of these, with one of their PDU’s in particular really shining
https://www.geistglobal.com/power-distribution-unit/NS30025L

The sheer quantity and distribution of ports is where this PDU really shines. It allows for you to have an amazingly organized cabinet like this by keeping a port near wherever you need it, see how all the power cables travel horizontall (excuse the service plug for a laptop). This makes things incredibly clear and safe to work in without risk of unplugging:

The Vertiv Geist 208V PDU has each one of these ports switched individually so you could remotely shut off a single port if you wanted that functionality. A perhaps under-rated feature of these PDU’s is that the main power cable to outlet protrudes out of the side of the PDU versus the bottom, unlike the standard APC PDU design, which can often cause stress as well as mounting challenges for the PDU. These sit right on my cabinet ledge with no problems. Finally, Vertiv is always expanding functionality and ecosystem sensing with their platforms, and they are a good solid company to invest in long term if you have to buy equipment.

The Best 120V PDU:

So if you read the rest of the article, you are going to try to stay away from 120V PDU’s in general, but if you must – check this PDU out from Vertiv as well. It does not have all of the “bells and whistles” in terms of port density, remote switching, etc. but it does one really important thing which makes it a great contender for small applications: It gives me C14 receptacles which gives me the chance to insert sleeves and properly secure them and eliminate the most common source of in-cabinet outages (dislodging).

https://www.geistglobal.com/power-distribution-unit/27959

This thing is really cool in the fact that it works with 120V as well as 208V sources – which is a feature not many PDU’s have the capability of. You will need to purchase a custom power cable to hook up to preferably a locking receptacle – you can find one like that here from our friends at StayOnline or buy one from Vertiv themselves, don’t forget to get a sleeve insert for the C19 connector as well as your C14 sleeve inserts that we talk about above (https://www.stayonline.com/power-cords/iec-320-female-over-mold-inserts-8436.asp) : https://www.stayonline.com/pc_product_detail.asp?key=1DE670C48E2F43C1944D112253E04516

This is a really solid and versatile PDU – its best feature is its receptacles which is industry rare, but its also at an extremely cheap price point floating around the $200-300 dollar range so you cant really lose with this if you are looking for an extremely small deployment that doesn’t need a lot of features.

Single Corded Devices? Get This:

The Uptime Institute makes concessions for single corded devices even in Tier IV facilities. Although not recommended, they allow a Static Transition Switch (Sometimes, incorrectly in my opinion, called ATS) in rack to source select.

I like Tripp Lite for these products because their STS units are rated to accept two separate non-homogenous sources. If you look at the spec sheet for the Vertiv Geist units, they require phase synchronized sources – which is often times not the case from a 2N redundant system of isolated UPS’s. (The UPS’s are generally NOT phase synchronized).

If you MUST – on the 120V – this is really your best option, which does relegate you to the straight blade NEMA plugs: https://www.tripplite.com/1.9kw-single-phase-ats-metered-pdu-120v-16-5-15-20r-2-l5-20p-5-20p-adapters-2-12ft-cords-1u-rack-mount-taa~PDUMH20AT

We haven’t found anything on the market with a C19 plug that can pass us through safely to C14’s for 120V STS’s, but if we do find it we will update you and let you know.

For 208V, you have a great choice here: https://www.tripplite.com/3.2-3.8kw-single-phase-ats-metered-pdu-200-240v-8-c13-2-c19-2-c20-12ft-cord-1u-rack-mount-taa~PDUMH20HVAT

Make sure that you get the appropriate adapters of locking type receptacles as well here if possible – you can find those at Stayonline (https://www.stayonline.com/category/c-nema-twist-locking-cords.asp, https://www.stayonline.com/category/c-straight-blade-locking-cords.asp ). It is worth noting that these devices do not have internal breakers, so if a fault were to occur on the single power supply for your computer, you could risk the transfer of a fault between your redundant sources. For this reason, we do not recommend hooking them up directly to your redundant PDU’s in a mixed cabinet of dual corded load and single corded load – but if you have to understand the risks here. On remediation would be to run an alternate set of receptacles from an independent set of breakers to your cabinet and hook the STS’s directly up to that. This is a costly endeavor – I know. The best thing to do, at the end of the day, is to get dual corded devices.

Tying It All Together:

There are literally hundreds of options for PDU’s on the market. We wanted to distill them down to a few of our favorites and their accessories. If you are shopping to setup a new Colocation cabinet or data center deployment this should help cut your time down significantly. Many customers are finding that they prefer to not deal with these things and are looking to the cloud as a solution, which leads to a whole plethora of other problems. We recommend private cloud solutions, and see a lot of hybrid private cloud with providers such as our partner Netdepot. Our most successful insight we ever had though was distilling all of our years of experience with these granular type of “nuts and bolts” and offering the worlds first fully managed colocation experience Colo+ — you can learn more about our Houston colocation offering and our Houston Datacenter experiences and cut the hassle of buying anything for your cabinet ever again – just send us your gear in the mail and enjoy the best of both worlds.