Bus bar separation 4

[a10jp]

Where can I find separation requirement for busbar for distribution switchgear? We have voltages at 480V, and 3300/6600V.

 

[jmmee97]

a10jp,
The National Electrical Safety Code (NESC) has tables listing the minimum established spacing for the different voltage levels. I believe this would include switchgear.

 

[jghrist]

The NESC would not cover separation requirements within the switchgear. If in the US, you need to see the relevant C37 series IEEE/ANSI standards. See

http://standards.ieee.org/prod-serv/index.html

 

[jraef]

Actually, the original poster needs to define his geographic location, as standards vary around the world.

"Venditori de oleum-vipera non vigere excordis populi"

 

[alehman]

The NEC also has spacing requirements.

 

[stevenal]

NEC also deals with installation. See Jghrist's answer above. I'm guessing the poster is in DC, so USA standards apply.

 

[a10jp]

Hi all, thanks for the feedback. I have looked at the code and NEC Table 408.56 talks about minimum spacings. However, this table talks about system not over 600V, where 50mm spacing is required. By deduction, if you have 6600V the spacing should be higher. The location is US installation within Japan. The local code requires only 20mm spacing regardless of the voltage. In reality, many times the busbars between phases in these high voltage/medium voltage switchgear incoming section are installed very close together. I wonder if the 2" spacing requirement is actually satisfied.

 

[dwftx34]

Just a comment from a field electrician but the minimun spacing requirement for arc gap protection listed in the NFPA and NEC and do not take in to consideration protection during fault conditions most manufactures use greater distances to provide phase contact protection during equipment failures and the IEEE and ANSI standards would apply

 

[jraef]

This thread is now a bit old, but I came accross the following tech paper on this very subject from a well respected switchgear manufacturer.

http://www.powellind.com/main/Uploadpdf/ptb-59.pdf

"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more."
Nikola Tesla

 

[alehman]

See NEC 490.24 (2002 version) for over 600 volts. Most U.S. equipment manufacturers use other standards such as ANSI and NEMA for design.

 

[a10jp]

Thanks. These are all good info. I realized now that mnanufacturer standards can be different than the code requirements. As the examples show above, the manufacturer data sent by jraef shows bare metal for 5kV setup requires only 3.5" clearance whereas the NEC Table 490.24 requires 4.5".