Medium Voltage Clearance

Status
Not open for further replies.
Lady Engineer

Lady Engineer

Senior Member
Location
New Jersey
Ok...here's the scenario of my project.

I have 2 transformers and a medium voltage switch all are situated on the property. I want to surround them by one fence (there are kids around). I know JCPL wants 10' in front of their tranformers doors for working clearance. What type of clearance do I need for the medium voltage switch (14.4 KV)? Should it be taken from 110.31 or 110.34? :confused:



Lady :)
 
The purpose of 110.31 is to keep the public away from the equipment. It is to prevent some jokester from reaching in with a long pole, and drawing an arc. The purpose of 110.34 is to provide sufficient room for the worker to be safe.

So if your set up is such that the switch is in between the two transformers, and such that its doors open in the direction of one of the transformers, then you need either 6 or 9 feet (but not 15) between the switch and the transformer. It would be 6 feet if the transformer has no opening in the direction of the switch, and 9 feet if it does (i.e., Condition 2 versus Condition 3). But you get the number from Table 110.34(A), not from Table 110.31.

You will need 15 feet of space between the fence and any of your three components. That number you get from Table 110.31.
 
Charlie,
I have to disagree with one this. Table 110.34 states nominal voltage to ground. 14.4 KV (in a wye system) is less than 9000V so condition 1,2 and 3 would be 4, 5 and 6 ft respectively. Of course, the design of the system needs to be considered. If you need hot sticks to operate more clearance may be needed.
 
Nick said:
Charlie,
I have to disagree with one this. Table 110.34 states nominal voltage to ground. 14.4 KV (in a wye system) is less than 9000V so condition 1,2 and 3 would be 4, 5 and 6 ft respectively. Of course, the design of the system needs to be considered. If you need hot sticks to operate more clearance may be needed.
Click to expand...

It's medium 14.4KV on the primary...but my real question is about the fence....because my supervisor says the fence it only if the parts are exposed. :confused:

Lady :)
 
Status
Not open for further replies.
Top