How much spacing should you have when testing cables?

[cjones09]

We can't always test cable in free air, sometimes it might be down in a hole or in a cabinet. My question is what is the minimum distance I need to keep my cables from arcing when testing with high voltage? :confused: Someone once told me a good rule of thumb is 1" per kV, is this correct?

[ArchIsChompa]

It depends on the voltage, really. I believe what you were told, 1ft. per kv, is more than enough to keep you and whatever equipment around you safe.

[cjones09]

You must have misread my post, I was told 1 inch per kV not 1 foot.

[ArchIsChompa]

You know what's funny, I was thinking about this the past couple of days. I did misread this, haha, but 1" per kV.. I don't know. I'd feel more comfortable with ~2". This is just my safe take on this. I should assume that some company has this set in stone. I'll do some research and get back to you on that.

[ArchIsChompa]

Man, I can't find anything on this. I did manage to find some paperwork about cable insulation when using electrical tape. As far as bare cable to cable, I asked multiple people with 20-30+ years and they told me they just go off what they feel comfortable with. I'll continue to look, but as far as set in stone goes, I wouldn't say there is anything.

[SecondGen]

After using the Google machine I was able to find a pretty interesting paper that references 1 inch per 10 kV for bare conductors in free air:


With bare conductors, air is the insulator, and clearance distances can be calcuated using standard values for the breakdown of air. A common rule of thumb which is very conservative is 1 inch per 10 kV. Since the breakdown field for air is around 71 kV/inch, this provides a 7:1 safety factor.
http://home.earthlink.net/~jimlux/hv/hvwire.htm