Distance from open termination point to ground?

[minerman]

Hi,

Is there anything in the NEC that specifies a minimum distance from an open terminal to ground? More specifically, we have a heating element terminal that is close to a grounded vessel wall. Does the NEC say anything about how close this terminal is allowed to be to the wall?

Obviously it's going to arc if it's too close to the wall. As long as we design so that it's not too close to the surface, so that it wont arc, are we in the clear?

 

[kwired]

Hi,

Is there anything in the NEC that specifies a minimum distance from an open terminal to ground? More specifically, we have a heating element terminal that is close to a grounded vessel wall. Does the NEC say anything about how close this terminal is allowed to be to the wall?

Obviously it's going to arc if it's too close to the wall. As long as we design so that it's not too close to the surface, so that it wont arc, are we in the clear?

Under 600 volts will not arc without some help from "contaminants" to bridge the gap. Transient voltages on the line will also help get an arc started.

I will not say NEC never mentions such clearances, but I think such clearance commonly comes from other sources more so then NEC.

 

[Smart $]

As mentioned, not specified by NEC for LV installations. For HV applications, see 490.24.

For LV applications, you can use the following as a guide...

http://www.wecoconnectors.com/data_source/fichiers/ul_csa_specification.pdf

 

[mgookin]

Hi,

Is there anything in the NEC that specifies a minimum distance from an open terminal to ground? More specifically, we have a heating element terminal that is close to a grounded vessel wall. Does the NEC say anything about how close this terminal is allowed to be to the wall?

Obviously it's going to arc if it's too close to the wall. As long as we design so that it's not too close to the surface, so that it wont arc, are we in the clear?

What's in the vessel?