Substations fence to live parts distance requirements

[jaraujo1]

I was requested to become the arbitrator for the above subject in between 2 parties.

Background info: the substation is 20.8KV and the HV gear is out in the open enclosed in cabinets.

Party 1 claim that article 110.31 clearance table is the applicable table.

Party 2 claim that article 110.34(E) is tha applicable table.

My approach is as follows:
110.31(D) is the exception for table 110.31 and 110.34(E).

110.31(D) "enclosed equipment accessible to unqualified personnel" exceptions are:
- Ventilating or similar openings in equipment shall be
designed so that foreign objects inserted thru these
openings are deflected from energized parts.

Here is my take on this:
Both 110.31 and 110.34(E) tables refer to " live parts"
if the hv gears are enclosed as described above we have no live parts to worry about and the distance from the fence to the enclosed hv gear is a mute point. I need to focus in the distance from any exposed above the ground live parts such as connection points that are accesible and could cause bodily harm to unqualified personnel and the fence.

However this is not the answer to my question.
The issue is when is table 110.31 applicable versus table 110.34(A) ???


Any feedback will be appreciated.

 

[charlie]

I am assuming that these facilities are all privately owned and are not part of an electric utility's service.

Table 110.31, Minimum Distance from Fence to Live Parts is just that. The safety is provided laterally from an installed and protective fence. Table 110.34(A), Minimum Depth of Clear Working Space at Electrical Equipment is dealing with the actual working clearances in the same manner as 110.26 does for 600 volts and lower. Table 110.34(E), Elevation of Unguarded Live Parts Above Working Space is dealing with unguarded live parts above the working space by way of elevation.

In my opinion, the live buses, terminals, etc. found in substations are being discussed in these tables to protect the unqualified persons and to provide working clearance for the qualified workers. In other words, they all apply, just to different things.

 

[jaraujo1]

Charlie,

Thanks....I agree 100%. I just came up with the same answer before I read your reply.