panelboard feeders in buried rigid conduit

Status
Not open for further replies.

DW98

Member
for old panelboard feeders in buried rigid conduit where conduit was used as ground without grounding conductor, is there a way to test the integrity of grounding? would you have to install a new overhead feeder to be sure grounding path is intact?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
for old panelboard feeders in buried rigid conduit where conduit was used as ground without grounding conductor, is there a way to test the integrity of grounding? would you have to install a new overhead feeder to be sure grounding path is intact?

there are ways to test such things. I think there is even a meter for making the test.

whether the testing is really beneficial or not is something else.

what makes you think there is a problem with the rigid UG?
 

DW98

Member
response to Bob

response to Bob

A client had a lot of low voltage systems - Fire Alarm, HVAC controls get fried by lightning and requested we look at how to protect building. On my visit to site, the topic of grounding was also introduced, the client was concerned that old building (school) wasn't grounded properly. So, I went to site for what I thought was one issue (lightning) and it became two separate issues. Most of the original panelboard feeders are slabbed in conduit. From what I've heard from contractors and others, rigid conduit may degrade or rust out over time. I don't know if this happens or has happened so I was wondering if there's a way to test ground path.
 

John120/240

Senior Member
Location
Olathe, Kansas
I don't know if this happens or has happened so I was wondering if there's a way to test ground path.

A rather crude method but....use an appropriate length of wire either THHN or Romex, attach one end of wire to conduit go to opposite end & check for continuity. Others will chime in with more reliable methods.
 

kwired

Electron manager
Location
NE Nebraska
A rather crude method but....use an appropriate length of wire either THHN or Romex, attach one end of wire to conduit go to opposite end & check for continuity. Others will chime in with more reliable methods.

That will prove continuity which may be a good start but will not prove any level of fault carrying ability which IMO is what matters the most. One may read less then an ohm or two with a standard digital meter, but put fault on it that should draw 8000 amps if everything is in good condition and the overall impedance may rise dramatically.

Fool proof method would involve injecting a reasonable amount of test current and see how it responds. Doing so can introduce other issues though, not certain what tools are available specifically for this purpose.
 

kwired

Electron manager
Location
NE Nebraska
Status
Not open for further replies.
Top