Megging after rough in

[electrofelon]

Does anyone find it kinda odd that we dont do this? Plumbers pressure test their supply and waste lines, why don't we test our circuits? I am thinking primarily with residential. Particularly now with AFCI's it would find inter-neutral bonds and N-G bonds. I heard once this is standard in other parts of the world, is that true? I think if I was charged I would dump all afci's and require megging.

 

[jaggedben]

Would it find potential series arc faults?
Also wasn't part of the idea with arcfault to protect appliance wiring?

I mean, seems like a good idea to do it. But not sure how it addresses arc fault stuff.

 

[Jim Reizner]

Residential plumbers do not pressure test residential water systems - they just turn the water on and check for leaks.

Similarly residential electricians don't megger - they just turn the circuit on and see if the circuit breaker / GFCI / AFCI trips.
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Pipe fitters or others in industrial systems will pressure test piping systems per specifications.

I have decades of work in industry. Our electrical contractors meggered all 480 VAC and higher lines. We had a minimum resistance value. More than once they repulled because of low megger values.

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As you know there is no requirement in the NEC that residential 120 / 240 VAC systems be meggered. I would find that to be a waste of time. but of course there is noting stopping one for doing so if so desired.

If you feel strongly about this you can submit to the NFPA for a change.

 

[AC\DC]

Plumbers hear pressure test. Good idea on doing an insulation test, though would have to be mandated since no customer would willingly pay lol

 

[Little Bill]

Residential plumbers do not pressure test residential water systems - they just turn the water on and check for leaks.

Similarly residential electricians don't megger - they just turn the circuit on and see if the circuit breaker / GFCI / AFCI trips.
---

Pipe fitters or others in industrial systems will pressure test piping systems per specifications.

I have decades of work in industry. Our electrical contractors meggered all 480 VAC and higher lines. We had a minimum resistance value. More than once they repulled because of low megger values.

---
As you know there is no requirement in the NEC that residential 120 / 240 VAC systems be meggered. I would find that to be a waste of time. but of course there is noting stopping one for doing so if so desired.

If you feel strongly about this you can submit to the NFPA for a change.

I've done several new construction residential, and also helped others do the same. All the plumbers pressure test their plumbing with compressed air.They leave a gauge on it for several days and check for leaks. Some use water, but most use air. I think most just use water for the drains. Maybe your area doesn't, but it's required here by building inspectors.

 

[electrofelon]

Residential plumbers do not pressure test residential water systems - they just turn the water on and check for leaks.

.

In Seattle it is pretty much universally done, supply and DWV. I believe it is code that it be done, but I don't know what code it is in.

 

[electrofelon]

Would it find potential series arc faults?
Also wasn't part of the idea with arcfault to protect appliance wiring?

I mean, seems like a good idea to do it. But not sure how it addresses arc fault stuff.

I think it would find an event that could result in a series arc, like a nail thru the wire. Then there are parallel arcs neutral - neutral bonds, and neutral ground bonds.

Sometimes I just have little thought experiments imaging what aliens would think of they analyzed the way we do things, having no preconceived notions. Given Romex, staples, idiot installers, nails, seems like perhaps a no brainer?

No one addressed the rumor that this is done commonly/universally in other parts of the world. Does anybody know?

 

[ron]

Just to be devil's advocate, how do you comply with 110.7 with testing the insulation resistance?

110.7 Wiring Integrity. Completed wiring installations shall be free from short circuits, ground faults, or any connections to ground other than as required or permitted elsewhere in this Code.

 

[wwhitney]

In Seattle it is pretty much universally done, supply and DWV. I believe it is code that it be done, but I don't know what code it is in.

Washington state uses the UPC, so the references are:

Chapter 6: Water Supply and Distribution, Washington Plumbing Code 2021 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

Chapter 7: Sanitary Drainage, Washington Plumbing Code 2021 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

Cheers, Wayne

 

[electrofelon]

Just to be devil's advocate, how do you comply with 110.7 with testing the insulation resistance?

110.7 Wiring Integrity. Completed wiring installations shall be free from short circuits, ground faults, or any connections to ground other than as required or permitted elsewhere in this Code.

I am not following Ron, can you elaborate?

 

[Little Bill]

I think he is saying how do we prove 110.7 without some sort of testing.

 

[hbiss]

I think he is saying how do we prove 110.7 without some sort of testing.

The test is when everything is powered and there are no problems. Nothing there says that testing has to be done before power is applied.

-Hal

 

[wwhitney]

I think he is saying how do we prove 110.7 without some sort of testing.

110.7 presents an affirmative obligation of the installer, but does not require testing to prove that obligation is met. If an inspector is going to fail an inspection by citing 110.7, I would think the inspector would need to indicate where the "short circuits, ground faults," or inappropriate connections to ground" are located. Unless there's some other verbiage in Article 110 or the like that indicates the inspector can require testing as desired?

Cheers, Wayne

 

[RdmanElect]

A simple grounds check with an ohms meter is a good practice to make sure you don't have any direct shorts to ground.I do this when I have all my wires terminated to breakers and I'm about to turn them on.

Sent from my Pixel 7 using Tapatalk

 

[electrofelon]

A simple grounds check with an ohms meter is a good practice to make sure you don't have any direct shorts to ground.I do this when I have all my wires terminated to breakers and I'm about to turn them on.

Sent from my Pixel 7 using Tapatalk

Yeah I did a house a few years ago, framed 2x4, give me the heebie-jeebies. Roughed it kinda while the siding was going up, I was a little ahead of them. I rang everything out when they finished the siding and went around and tugged on the cable at holes to make sure a nail hadn't gone thru it.

 

[letgomywago]

Yeah I did a house a few years ago, framed 2x4, give me the heebie-jeebies. Roughed it kinda while the siding was going up, I was a little ahead of them. I rang everything out when they finished the siding and went around and tugged on the cable at holes to make sure a nail hadn't gone thru it.

I've done the tugging thing before when there's wall getting siding or they left 2 inch drywall screws on the floor

 

[jaggedben]

Okay guys, neutral-to-ground faults at receptacle boxes that are not downstream of a GFCI device. After the boxes are made up with the receptacles. How do you test for that when everything is made up? AFCI doesn't catch it.

 

[rambojoe]

A plug tester will.

 

[Little Bill]

The test is when everything is powered and there are no problems. Nothing there says that testing has to be done before power is applied.

-Hal

110.7 presents an affirmative obligation of the installer, but does not require testing to prove that obligation is met. If an inspector is going to fail an inspection by citing 110.7, I would think the inspector would need to indicate where the "short circuits, ground faults," or inappropriate connections to ground" are located. Unless there's some other verbiage in Article 110 or the like that indicates the inspector can require testing as desired?

Cheers, Wayne

Guys, Electrofeline asked Ron what he meant by the statement. I was just giving my guess at what he was meaning. I never said a test had to be ran.

 

[electrofelon]

Okay guys, neutral-to-ground faults at receptacle boxes that are not downstream of a GFCI device. After the boxes are made up with the receptacles. How do you test for that when everything is made up? AFCI doesn't catch it.

An afci will indeed trip on a N-G bond in the branch circuit