Equipment Grounding in the Data Center

Electrical

Thursday, 11 September 2008 14:35

Written by Rakesh Dogra

I will not go into the physics of this phenomenon but static electricity is certainly a big problem when dealing with equipment containing sensitive electronic parts. The data center is filled with such equipment and therefore proper measures must be taken to prevent damage to these costly equipments.

What is meant by Grounding?

In context of electricity, grounding refers to the process of connecting and electrical appliance or electronic equipment to the earth with the purpose that any excess charge would flow into the earth rather than harming that particular equipment. The earth is considered to be a literally infinite sink which can absorb any amount of charge without raising its potential level. The reference potential level of the ground or the earth is taken as zero. Grounding is used in various scenarios and one common sight is the long metallic rod that you must have seen on top of high buildings which tends to absorb electricity from lightning during thunderstorms and pass that safely to the earth without causing harm to the structure of the building or the residents therein.

Grounding the Equipment

Grounding is not only useful in protecting buildings but also sensitive and costly electrical and electronic equipment. A simple and effective way of protecting the equipment against the voltage surges resulting form electrostatic discharge, circuit switching and natural phenomenon such a lightning is to earth these equipment. This is very important since a data center consist of very costly equipment worth thousands and millions of dollars including but not limited to routers, servers and so forth. These equipments are very sensitive to voltage surges and here are some facts which would help you estimate the sensitivity as well as scale of the problem.

• Nearly one-third of the damage in the data center equipment results from electrostatic discharge

• The lightning from the sky consists of millions of volts whereas only few ten volts are required to cause damage to sensitive electronic equipment, hence the necessity to isolate the equipment from lightning effects need not be overemphasized.

• Other sources of voltages surges include switching electrical devices ON and OFF such as air conditioners, monitors etc.

• Millions of dollars are lost every year due to faulty equipment which are as a result of improper grounding

• Several million dollars are lost indirectly due to the downtime of the data center apart from the cost of replacing equipment as listed in the previous point

The above facts should act as an eye opener and make us realize the importance of grounding in the data center.

How to go about Grounding

It is all very well to know that grounding is very important for the data center equipment, but it is equally important to realize that unlike simple home electrical appliances, connecting a third ground cable apart from the two electrical wires is not alone sufficient for proper grounding and safety of the data center equipment. Of course that is necessary as well but we need to go beyond the basics of putting the ground cable and just follow the guidelines of the local safety and regulating authorities.

The main reason for this is that the regulations and codes adopted by regulatory bodies are quite generic in nature and are mainly designed keeping in view the safety of the personnel rather than the equipment. There are two main industry standards which specify the grounding standards in industry and they are as follows

TIA-942: this stands for Telecommunications Infrastructure Standard for Data Centers and covers all aspects of electrical grounding in context of data centers.

J-STD-607-A: this stands for Commercial Building Grounding and Bonding Requirements for Telecommunications and is a generic code for every type of commercial building whether it is a data center or not and hence it does not cover the aspects of rack and equipment grounding which is catered to by the TIA-942.

Hence these standards when combined with the local safety standards such as the National Electrical Code or NEC, tend to create an environment which ensures maximum safety not only for the personnel (which is certainly primary) but also of the costly equipment, the damage to which could lead to huge losses directly and indirectly due to downtime of the data center.

It must also be mentioned at this stage that the TIA-942 standards also have classified the grounding infrastructure available within a building or structure into tiers ranging from tier-I to tier-IV. Tier I represents the lowest range while tier-IV represents the most rugged standards ensuring at least 99.995% availability of the data center.

Of course a detailed analysis of these standards would not be feasible in this relatively short and introductory paper. One could visit the TIA website and several other resources for more detailed information about these standards. Also I would suggest reading this paper which will give you some more detailed information about grounding in context of the data centers.

Summary

Last but not least the discussion can be concluded by stating that given the immense magnitude of losses which could result from improper grounding of the equipment in the data center; it is always wise to take precautions before it is too late. A minor surge of voltage could produce catastrophic results and could literally ruin a company and its reputation. There is a popular story about how a battle was lost due to the want of a horse shoe nail, and certainly the data center administration would not like to relive that scenario in the modern times.

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