Introduction – Data Center Power

Welcome back to the next part of our series on the proper way to order colocation. In this series of Datacenter-Discovery, we will cover key items when ordering colocation or pricing enterprise & meet-me room colocation. These items are as follows:

Power Circuit Whip and Type (120v & 208v)

When trying to figure out if you need 120v or 208v of power, you should try to think about what your load is going to be like.

What is a ‘load’? An electrical load is an electrical component or portion of a circuit that consumes electric power. This is opposed to a power source, such as a battery or generator, which produces power.

In the colocation world, your load is going to be the servers, switches, routers, anything in your cabinet/cage space.

Once you have an idea of your load, you can then start to get a better idea of which circuit type you’ll need. Make sure you understand what your equipment requires in power as well.

The circuit types you can choose from (in most datacenters) are either 120v or 208v. What are the differences?

120v = x1 120 v hot leg + neutral leg + ground leg

208v = x2 120 v hot legs + ground leg


Putting a voltmeter between the x2 120v hot legs gives you 208 volts total.


Sourced from Webhosting Talk

Aside from these differences, you can also note that 208v of power will cost you twice as much as 120v.

A+B Configuration

Many colocation providers, if not, most have data center power configurations in place to support the failover of power during any kind of outage or minor power/circuit failures. One of these configuration types is known as A+B Power.

Another way to generalize A+B Power is to think of a 2N Redundant Power environment. If there is an A-side to the power then there is a mirrored B-side for redundancy.

If power fails on one side, the other side will pick up the slack.

PDU Selection

The next thing we’re going to talk about in data center power is PDUs (Power Distribution Units) and what to consider when you order colocation.

First, you need to find out if the data center you’re migrating to will provide you with a PDU. If they are providing you with one, you need to find out if it is a Zero U PDU or if it is a Rack Mounted PDU.

Zero U PDU’s will sit on the inner wall of the cabinet which helps conserves cabinet space.

A Rack Mounted PDU will take up around 1U or 2U’s of space. In Ep. 3 of Datacenter-Discovery while we where mapping out our cabinet on Lucidchart, we mapped out a 1U PDU.

If the data center doesn’t provide you with a PDU then you should take the following suggestions into consideration:

One final note about your PDU, remember to follow the 80% rule! Never pull more than 80% of your allotted power to leave room for unexpected fan spin-ups/data center power increases.

PDU Monitoring

If you have the option of monitoring your PDU, I suggest you take advantage of it.

It’s important to know the amount of power you’re drawing at the moment you’re using it. This is to keep the data center’s SLA in check and prevent any misinformation that may cause issues.

Not to say that your provider isn’t trustworthy, but it is always important to stay on the safe side.

PDU Connector Types

Datacenter Power

20A 110V = L5-20 Connector

Order Colocation

30A 110V = L5-30 Connector

20A 208v = L6-20 Connector

30A 208v = L6-30 Connector

Common Planning Mistakes

When people and businesses migrate their networks into a colocation environment, they aim to size up their power based on their current data center power needs.

Sizing up your power needs to match your power usage can be a bit tricky, but you can easily avoid any factoring errors by simply doing the math.

In our example in the video, we bring up a Dell Z750P which needs 750W of power. This equates out to 6.26A of 120v of power. So if we need 10 of these, we can do the math and figure out that this will pull around 63 Amps of power total.

So if we are to break this measurement of 10 servers down, we can assume that we will need around 9 to 13 Amps of power per server. This is to keep the 80% rule in mind, leaving us about 20% of free power for unexpected activity/spin-ups.

Final Thoughts

Data center Power is something we take very seriously in our facilities and we hope you are able to take something away from this episode. The next topic we’ll be going over is Datacenter Connectivity. This is going to be a big one.

Once again, stay tuned, and connect with me on LinkedIn to talk more or shoot me an email at mark@jaxnap.com.