Continuity of Large Underground Conduit

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Sparky555

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Any suggestions on a good way to check continuity of a 150' run of large underground conduit (3-4"?). It goes to a 400A subpanel with 3 wire (1PH) so the conduit is the EGC. Normally I'd think of something like vise-gripping a 10 ga wire to one end & checking resistance between the wire & pipe at the other end. The issue I'm thinking about is there'd be resistance (although not open if continuous). Any better way?

Dave
 
Not sure what you are trying to accomplish? Surely if the conduit is an egc you only need to test from phase conductor to the pipe. Are you trying to see if there is continuity or how much resistance is on the pipe?
 
Certain Ideal Sure Test models have a ground impedance test function that you could use at the far end of the conduit, hot to pipe. I'm not sure what kind of a load it used for this check, but it's better than nothing.
 
I guess I didn't state my concern very well. If this were 4 wire w/o conduit the required EGC would be something like 1/0 copper capable of carrying approx. 150A. I'd like to know if this 3-4" conduit is an effective EGC w/o connecting it to 150A load.

Dave
 
Sparky555 said:
I guess I didn't state my concern very well. If this were 4 wire w/o conduit the required EGC would be something like 1/0 copper capable of carrying approx. 150A. I'd like to know if this 3-4" conduit is an effective EGC w/o connecting it to 150A load.

Dave
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Normally, I the conduit would be better than the 1/0 copper, however if the conduit is corroded I guess that could be an issue.
 
Ya, UL will come out and test. They put ~~ 20amps at 24 volts on a #10 wire. Ground must hold for two minutes. They check amps and voltage drop. That?s more of a job for an engineer, that is only for a Professional Engineer with a stamp and all.

As an EC you can?t check your own stuff, nor can?t your have another EC check it. Must be Professional Engineer. They charge a lot o money to do that.



What happened?

I bet the.....................
 
s.sparkomatic.r09 said:
As an EC you can’t check your own stuff, nor can’t your have another EC check it. Must be Professional Engineer.
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Now hang on a cotton-picking minute. You're stepping on my toes here. As an EC, I can check anything I darned well please. Furthermore, if I'm the one requiring the acceptance testing, and I only want some particular thing proven to me, I can certainly check it myself. If a third party is requiring the testing, unless they specifically state they want someone with certain qualifications to do the check, I'm also free to perform that test myself too. There probably are good reasons to have an engineering firm do certain tests, but to make the statement you just made on a wholesale basis is completely and utterly false.
 
Seems you could go to a machist handbook and get the qualifing electrical aspects/properties of you conduit run. Maybe the tables ...
My Dad taught me about continual testing... Ode to Dad!
I'd use a needle meter, do they still make those ? :roll:
 
This installation is over 30 years old & had a lightning strike which fried the panel. My concern is corrosion & the condition of the EGC.

"A Cotton-Picking Minute"...anyone over 30 knows what that is.

Dave
 
mdshunk said:
Certain Ideal Sure Test models have a ground impedance test function that you could use at the far end of the conduit, hot to pipe. I'm not sure what kind of a load it used for this check, but it's better than nothing.
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The Ideal SureTest is a no good glorified paperweight. You must not pay any attention to these folks here:rolleyes:
 
76nemo said:
The Ideal SureTest is a no good glorified paperweight. You must not pay any attention to these folks here:rolleyes:
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FWIW, I don't own one, and think it's a piece of junk too. I just recalled it had that function, so I was just throwing that out there as an idea for the list.

If this pipe suffered a lightning strike, it might well have improved the conduit connections.
 
mdshunk said:
FWIW, I don't own one, and think it's a piece of junk too. I just recalled it had that function, so I was just throwing that out there as an idea for the list.

If this pipe suffered a lightning strike, it might well have improved the conduit connections.
Click to expand...


Maybe you would feel the same about Fluke's 1653?:

http://www.pat-services.co.uk/fluke-1653-230.htm

I never know if some here are picking on Ideal or loop impedance testing itself. Like to shoot this one down Marc? I can find Megger's model if you'd like:roll:
 
76nemo said:
Maybe you would feel the same about Fluke's 1653?:

http://www.pat-services.co.uk/fluke-1653-230.htm

I never know if some here are picking on Ideal or loop impedance testing itself. Like to shoot this one down Marc? I can find Megger's model if you'd like:roll:
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I have no idea what you're talking about. The impedance test is what needs done. I was just agreeing with you that the impedance test function of the Sure Test probably isn't the best one to use for that. Many people own one already, which is why I mentioned it.
 
There seems an overabundance of unqualified hype around the Suretest, and perhaps worse an over-reliance by some inspectors not familiar with its limits. The Suretest manual warns the unit will be damaged if used repeatedly before its 30-60 second cool off period.

Anyone who owns one should check the voltage drop function. My OEM Suretest unit was several years old, made before Ideal acquired the brand.

A known load, checked with clamp probe and separate volt meter showed my Suretest voltage drop function off by about 7 volts, presumably since the expected 15A load resistor drifts over time.

However, the separate impedance function was still accurate, presumably because it measures the load current before calculating resistance.

This impedance function shows relative values of each conductor down to 1/100th an Ohm, including EGC's. Moving the EGC alligator clip adapter to conduit would check conduit impedance relative to other conductors, but no Megger testing like the Fluke 1653.

That Fluke is a very interesting load tester. Is the PFC/PSC (fault/ short circuit current) feature a circuit breaker test?
 
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