Data center electrical safety, avoide the flambe …


Today I’ve been thinking about the recent rash of electrical data center fires and failures, from The Planet’s explosion in Texas to the Fisher Plaza fire to the recent Omgeo fire in Boston (I ran across some more details about the Fisher Plaza fire). In this post I’ll be discussing how to deal with preexisting electrical infrastructure in your data center facility.

Unless you’re building a facility from scratch or doing a bare walls gut out of a building, chances are very good that you’ll be dealing with preexisting electrical facilities. This is especially true if you lease space in a building. So, how can you identify what can be safely reused and what should go on the junk pile?

Step one, throw away the aluminum. Aluminum wire and aluminum buss bars (such as the one that failed at Fisher Plaza) tend to have problems with loosening connectors as well as oxidation (if they’re not protected properly). These two problems can result in wasted energy (not what you want for a green data center), over heating, and even fires from electrical arcs, especially if the conductor is carrying thousands of amps of current). Copper conductors, on the other hand, while being more expensive, do not suffer from either of these problems.

If you are going to run any aluminum, inspect all connections before operating and establish a maintenance program to tighten all connections periodically.

Second, ditch any panels and over current protection devices made before the late 1960s. I’ve seen “fused neutral” panels from the early 1900s (a serious safety hazard) and circuit breakers from the late 1930s still in service in commercial buildings. When circuits breakers get very old, not only may they not trip but the lubrication inside the breaker may harden up, locking the breaker on. I’ve actually seen this happen, a Square D “992” breaker failed to trip on fault and basically pumped a full 600A entrance into a 15A circuit. The result was the destruction of the panel buss bars and much smoke, as well as a service outage.

Third item is transformers. All oil cooled transformers belong outside the building, period. Transformer explosions and fires are not good anywhere but the last place you want them is anywhere near your data center equipment. Older dry type transformers should be inspected for signs of over heating. I’ve seen transformers in live operation that had temperatures of 150 deg F on the outside of the case. Transformers that have been abused this way are much more likely to have insulation breakdown. If it’s suspect, replace it before you end up with a service outage or worse.

Finally, replace obsolete wire types. Type R (rubber with a flammable canvas outer jacket), TW, and THW are all still commonly found in buildings. In additional to now being up to modern current carrying standards, any of these may exhibit degradation of the insulation. Once again, it’s just a catastrophe waiting to happen.

This isn’t an exhaustive list but if you follow the recommendations here, you’ll avoid the biggest electrical traps that have plagued data centers for the last few years.

Vern, SwiftWater Telecom

data center facilities engineering

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