Why are breaker ratings so important? Should I care if my datacenter does not follow them?

Those who use datacenter services for their IT operations know much about OS technologies, databases, and server hardware, but unfortunately, many IT professionals are not familiar with safe power practices and the ramifications if they are not followed.

The most common area of confusion is the 80% breaker rating limit. Some datacenters will only allow you to run continuos duty equipment up to 80% of the breakers amp rating. For example, on a 20amp 120V breaker power feed, that means your limited to 16amps of continuous power draw. These datacenters are following national fire and electrical code standards, and they are operating in a safe environment.

The sad thing is many datacenters do not enforce the 80% rule, and instead allows their users to run all the way to 100% breaker rating of continous draw. In addition to running an unsafe environment, these datacenters further propagate the misnomer of how to effectively run your power environment. When you allow someone to do something that is incorrect, that person assumes it is correct since you let them do it. Time and time again we have seen new customers come into our facility and say, “my previous provider allowed us to do…”. We then have to break down that myth and explain that what they were doing was unsafe and a code violation.

Why is it dangerous to exceed 80% breaker rating?

Lets start with the obvious. First, your more likely to trip your breaker. Second, your more likely to degrade the lifetime of the breaker causing it to fail or false trip. And more importantly, you run the risk of an electrical fire. NEC standards for wire sizing are based on 80% limits as well, so if you run 100% breaker rating power through those wires 24×7, the wires will overheat. Over time, the excess heat can cause the jacket to degrade and eventually fail, causing a bare wire scenario which could trigger an electrical fire.

Additional concerns involve the slow degradation of your power system as a whole, including your UPS, invertors, and transformers. All electrical equipment is designed by the manufacturerto not exceed 80% max rating for more then 3 hours. If you do exceed the limit, you violate the warranty and run the gear in a fashion that it was not designed for.

Why would a datacenter violate the 80% power rule?

There are many reasons. One is money. By allowing customers to pull a few extra amps, they can get a bit more business since their offering will appear cheaper. Another reason is they lack the ability to monitor power usage. A more serious reason, though, is there is a lack of communication between sales people, customer service, and operations. The operations people may know its wrong, but the sales people dont, and they allow it to occur. Its not caught due to the communication breakdown.

What does this all mean?

Simple. Stay away from datacenters that dont enforce 80% breaker limits when looking for a colocation provider. If they dont, they run an unsafe environment. By itself, it may not seem like a big deal, but that environment usually will fail to meet other criteria of a quality provider. In some ways, the handling of power infrastructure is a litmus test for quality datacenter operations as a whole. If the operations group of a datacenter provider has a very good handling of power, more often then not, they have a good handle on everything else!

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