Before bidding for a telecommunication bonding and grounding contract on a project, first you need to determine the following factors:
Who’s responsible for each portion of the bonding and grounding?
Establish whether Electrical Division 26 or Telecom Division 27 are the responsible party.
Which standard is being referenced?
Be clear if you will be working with 607-A, 607-B or the soon to be released 607-C.
Is the grounding and bonding design complete?
It’s vital to fully establish this information. Otherwise, how do you accurately estimate parts and labor for the project? Many project specifications only reference a set of standards for the bonding and grounding and lack any design plans or requirements.
Do you have a copy of bonding and grounding standards to know what the project requires?
In order to be able to estimate time-scale and costs of your bonding and grounding build accurately, you’ll need up-to-date lists of all current standards. Below is a list of the standards:J-STD-607-A 2002 Commercial Building Grounding (Earthing) and Bonding Requirements for Telecommunications. Released 10/2002, this is the most commonly referenced.ANSI/TIA 607-B-2011 Generic Telecommunications Bonding and Grounding (Earthing) for Customer Premises, 607-B-1-2013 Addendum 1 and 607-B-2-2013 addendum 2. These are the most current versions.
How do bonding and grounding standards differ? Here’s a refresher
607-A only refers to bonding and grounding between rooms using the BCT, TBB and GE (see definitions below). For bonding in telecomm rooms themselves you have to refer to TIA 942 Data Center Standard. The maximum size 607-A conductor required is a 3/0 copper.607-B refers to the bonding and grounding between rooms, as well as the inside rooms, by incorporating the TIA 942 Standard. The big caveat you need to remember in regards to the 607-B is the increase in conductor size from 3/0 to 750MCM copper.607-B-1 refers to external grounding, grounding resistance, the electrode system design and grounding electrode system testing.607-B-2 references using the building steel as a substitute for the BCT, TBB and GE, but requires a two-point grounding and continuity test using an earth ground resistance tester.
Don’t forget costly materials
The big cost items to factor into any bonding and grounding contract bid are the busbars and compression connectors and conductors required to connect all the busbars together. This includes items such as TMGB (Telecommunications Main Grounding Busbar), usually placed at the EF (Entrance Facility), and TGB (Telecommunications Grounding Busbar), located in the TR’s (Telecommunications Room).The conductors used are the BCT (Bonding Conductor for Telecommunications), which is connected between the TMGB and Main Electrical Swithboard, TBB (Telecommunications Bonding Backbone) between the TMGB and TGB’s, and the GE (Grounding Equalizer) between TR’s on the same floor. The size of these conductors is based on length calculated at 2kcmil/Ft.The minimum size conductor required in a grounding and bonding project is #6 AWG, which is calculated as 26,240 cmil/2,000 cmil=13ft. This states that you’re only allowed to run up to 13ft of cable with a #6 AWG before having to increase the size of the conductor to 3/0 at 66ft (as per standard 607-A), and then up to a 750MCM conductor at 300ft (as per standard 607-B). The standards further state that of the BCT, TBB, GE, whichever is larger, all units used are the same size.Knowing which standard is being used and enforced can substantially affect your costs. For example, a 300ft run of 750MCM, including 2-hole compression connectors, crane to handle the reel and labor to install the conductor, will cost in excess of $7,000.
Knowledge is King
A highly recommended and useful publication to read in order to get a better understanding of what is required for the bonding and grounding is ANSI/NECA/BICSI 607-2010. This features relevant definitions, abbreviations and acronyms of components, conductor sizing based on the 607-A, images and much more information that is invaluable for bidding, designing and installing telecommunications bonding and grounding systems. It also references the bonding required in telecom rooms for the racks, equipment, cable trays and additional metal surfaces. The publication can be purchased from both NECA and BICSI and should be in the reference library of anyone working in telecommunications bonding and grounding.It’s important to note that people with an electrical background will often balk at the size of the bonding conductors and requirements as being overkill. However, the design of telecommunications bonding and grounding is not for carrying fault current to operate an overcurrent device, as required for electrical systems. Instead, the purpose is to protect the sensitive electronic equipment by providing an equal potential plane to protect against electrostatic discharge, high frequency noise and different potentials due to lightning strikes.Equipment failures caused by inadequate bonding are thus often not recognized as such due to this perception. Because the higher frequencies associated with networks travel on the surface of conductors, larger conductors are required than those used to clear electrical faults.The final question to address is whether the grounding and bonding requirements are being enforced. Whilst most government-run projects and many private projects require telecommunications bonding and grounding, the design and installation was not enforced in the past. This is rapidly changing, however, through increased regulation and observation.Now an RCDD (Registered Communications Distribution Designer) is required to be involved in the design, and/or oversee the installation and testing of the telecommunications infrastructure, including the bonding and grounding. It goes without saying to make sure to address these bonding and grounding requirements in your bid.Stephen P. Bunge, RCDD, ESSwww.wirehitech.com