Article 90
- Thread starter lbartsch
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Re: Article 90
A few are, most are not. Most operating companies use thier own standards which meet or exceed NEC requirements. Smaller companies which do not have the engineering resources will use standards from ANSI, BICSI, or buy another operating companies standards such as RBOC's, while others will use a specialized design/build firm who issues specifications. If the site is in a location like a high-rise building, the minimum NEC requirements have to be met, but usually the companies own practices meet/exceed the NEC requirements.
Is there a particular area of interest you have?
Edited for clarity.
[ March 23, 2004, 08:30 PM: Message edited by: dereckbc ]
A few are, most are not. Most operating companies use thier own standards which meet or exceed NEC requirements. Smaller companies which do not have the engineering resources will use standards from ANSI, BICSI, or buy another operating companies standards such as RBOC's, while others will use a specialized design/build firm who issues specifications. If the site is in a location like a high-rise building, the minimum NEC requirements have to be met, but usually the companies own practices meet/exceed the NEC requirements.
Is there a particular area of interest you have?
Edited for clarity.
[ March 23, 2004, 08:30 PM: Message edited by: dereckbc ]
Re: Article 90
There is a constant debate in house here about whether or not cellular providers such as Cingular, AT&T Wireless, etc. are exempt from code as per article 90.
They beleive that they are not subject to NEC code but they also do not have a consistant internal standard that they conform to (such as we did in the Bell System).
The problem boils down to the fact that if they are subject to code, its very difficult (if not impossible at times) to make the DC and RF portion of the installtion comply since code is not always clean on these partilular issues. I wish that the code committee would address electrical issues for those telecommunications companies that are not exempt.
There is a constant debate in house here about whether or not cellular providers such as Cingular, AT&T Wireless, etc. are exempt from code as per article 90.
They beleive that they are not subject to NEC code but they also do not have a consistant internal standard that they conform to (such as we did in the Bell System).
The problem boils down to the fact that if they are subject to code, its very difficult (if not impossible at times) to make the DC and RF portion of the installtion comply since code is not always clean on these partilular issues. I wish that the code committee would address electrical issues for those telecommunications companies that are not exempt.
Re: Article 90
ATT is one of the few wireless carriers that is exempt from code and considered a utility. Cingular is owned and operated by SBC, so I assume they are exempt. However, it is on a local by local basis, and if they are in a multi-tenant building not under their exclusive control like a high-rise, they will not be exempt.
Most of the wireless sites are built with pre-fabricated buildings constructed in a factory with all the equipment installed. IMO the code does address DC and RF systems used in wireless and telecom. IMO the wireless practices exceed/meet NEC. For example, the 24-volt DC systems are not required to be grounded, but you will find them grounded. The DC circuit and ground conductors are larger than required by table 310.16, and table 250.122. The only gray area I know of is with the batteries. We do not use fuses between the battery and charge buss, only if required by AHJ if they are involved and can catch it.
The coax sheath is bonded multiple times to the tower and where it leaves the tower. Once the coax enters the building it is connected to an entrance bulkhead with ADU?s. The bulkhead is a copper plate that extends all the way down to the ground ring or a copper plate with multiple conductors going down to the ground ring.
Grounding is another area that great care and extremes are taken. Most designs require a 5-ohm or less. This is accomplished by using a ground rings around the building, fence line, and around the tower. The tower and building foundations employ a Ufer ground. The rings will often use radials that extend out to the guy wires if employed. If soil conditions are poor we will use several chemical rods with the rings and radials to enhance the system. The GES is then brought into the building via the cable entrance bulkhead and used a single point reference for all the TVSS, ADU?s, AC service entrance, DC power supply, halo ground, and equipment frame grounds. IMO this meets any code requirement. Some may not go to this extent, but most do.
ATT is one of the few wireless carriers that is exempt from code and considered a utility. Cingular is owned and operated by SBC, so I assume they are exempt. However, it is on a local by local basis, and if they are in a multi-tenant building not under their exclusive control like a high-rise, they will not be exempt.
Most of the wireless sites are built with pre-fabricated buildings constructed in a factory with all the equipment installed. IMO the code does address DC and RF systems used in wireless and telecom. IMO the wireless practices exceed/meet NEC. For example, the 24-volt DC systems are not required to be grounded, but you will find them grounded. The DC circuit and ground conductors are larger than required by table 310.16, and table 250.122. The only gray area I know of is with the batteries. We do not use fuses between the battery and charge buss, only if required by AHJ if they are involved and can catch it.
The coax sheath is bonded multiple times to the tower and where it leaves the tower. Once the coax enters the building it is connected to an entrance bulkhead with ADU?s. The bulkhead is a copper plate that extends all the way down to the ground ring or a copper plate with multiple conductors going down to the ground ring.
Grounding is another area that great care and extremes are taken. Most designs require a 5-ohm or less. This is accomplished by using a ground rings around the building, fence line, and around the tower. The tower and building foundations employ a Ufer ground. The rings will often use radials that extend out to the guy wires if employed. If soil conditions are poor we will use several chemical rods with the rings and radials to enhance the system. The GES is then brought into the building via the cable entrance bulkhead and used a single point reference for all the TVSS, ADU?s, AC service entrance, DC power supply, halo ground, and equipment frame grounds. IMO this meets any code requirement. Some may not go to this extent, but most do.
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