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mgbinspect

Seeing Double

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Home built in 1989

One 200 Amp breaker panel with a 200 main disconnect within the panel.

They add a 125 Amp sub-panel dedicated to a generator. It is set up properly including a transfer switch.

They add a second main disconnect outside (maybe it was required). The new disconnect is grounded to the same rod as the main panel.

Has the main breaker panel now become a "sub-panel", requiring that the neutrals be isolated until they get back to the outside main disconnect?

If not, what makes the difference; the fact that the main panel is grounded to the rod? the presence of the main breaker still in the main service panel? Both?

Is everything sharing that same rod a problem?

I haven't seen this specific modification before.

What think ye?

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The simple answer is yes there can only be one main disconnect, the one closest to the meter.

The indoor panel has become a sub, so the rules for subpanels apply. No bonding of the neutral bus to the panel and no branch circuit ground wires to the neutral bus.

The grounding from the ground rods sounds wrong. There should be a 4 wire feeder coming from the outdoor panel going to the indoor panel, and that would include the grounding conductor. In my mind, the ground rod(s) should only be connected to that main disconnect. Was the work approved by an authority? I would call for it to be checked out regardless. The transfer switch grounding is also something to be checked.

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Thanks John. That's what I thought (neutrals/grounds), but since electical isn't my forte, I thought i'd bounce it off the brain trust, before I go down that road.

And, you feel the ground conductor from tfhe main panel to the rod should go away, now that it's become a sub-panel? That was the other thing that I suspected was the case.

Can the main disconnect in the panel remain, or does that need to be removed as well? Although, I don't imagine it can hurt anything, I suspect it's supposed to go away.

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I saw double as well no long ago.

There was 1 ground wire on the main water valve and another one on the water heater valve.

That wasn't a "ground" it was a bonding cable. Get a copy of Electrical Inspection of Existing Dwellings - 2001 by Douglas Hansen. Read it from cover-to-cover, go out and look at about 10 or 20 panels and systems, read it again from cover to cover, go out and look at about 10 or 20 more panels, repeat. Somewhere around the third read some of it will start to stick and make sense. By the fourth read you'll have it.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by John Kogel

[ . No bonding of the neutral bus to the panel and no branch circuit ground wires to the neutral bus.

john,

i hope you meant to say no branch circuit" grounding "wires to the nuetral bus?

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Wow, seems like I am not the only one asking those kind of questions... however, the guy answering was much more educational than many answer i've seen. He must be a professional! wow!

Yeah, except the answer is complete crap.

(Remaining post moderated.)

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Thanks John. That's what I thought (neutrals/grounds), but since electrical isn't my forte, I thought I'd bounce it off the brain trust, before I go down that road.

And, you feel the ground conductor from the main panel to the rod should go away, now that it's become a sub-panel? That was the other thing that I suspected was the case.

First of all, I'm not a trained electrician and I only know a smattering of the NEC rules, but ..Jim K will correct me if I flub this.... The grounding conductor should go only to the panel containing the main disconnect. The arrangement you describe results in parallel paths the earth, and that is to be avoided. Easily fixed.

Can the main disconnect in the panel remain, or does that need to be removed as well? Although, I don't imagine it can hurt anything, I suspect it's supposed to go away.

No, it is fine to keep it as a disconnect for the subpanel, as long as the other mistakes are corrected. It would be good to label that panel as a subpanel, but I don't think that is required, just helpful info for a confused homeowner.

Right, when I said branch circuit ground wires, I meant the bare grounding wires. [:)]

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There was enough wrong with it, to simply state that an electrician should do what is required, now that the main panel has become a sub-panel. It's going to get fixed. That's the important thing.

But, it would be great if someone could throw in their qualified two cents regarding the whole affair (specifics). I'd certainly like to learn how to properly address this, for future reference. [:-graduat

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Home built in 1989

One 200 Amp breaker panel with a 200 main disconnect within the panel.

They add a 125 Amp sub-panel dedicated to a generator. It is set up properly including a transfer switch.

They add a second main disconnect outside (maybe it was required). The new disconnect is grounded to the same rod as the main panel.

Has the main breaker panel now become a "sub-panel", requiring that the neutrals be isolated until they get back to the outside main disconnect?

I can't tell from your description. Where would you go to switch off all power to the building? If you'd go to the outdoor panel, then that panel has become the service panel and the neutrals should be isolated from the grounding conductors beyond it.

If not, what makes the difference; the fact that the main panel is grounded to the rod? the presence of the main breaker still in the main service panel? Both?

The thing that makes the difference is the presence of the disconnecting means -- the thing that shuts off all power to the building.

Is everything sharing that same rod a problem?

The sub panel should have a 4-wire feeder between it and the service panel - two hots, a neutral, and an equipment grounding conductor. If there's an additional conductor to the grounding electrode, that's fine. If, on the other hand, they're using the ground rod to terminate their equipment grounding conductor, that's wrong. You shouldn't be relying on the ground rod to clear faults.

Remember that the rod is part of the "grounding electrode system" which is completely and totally unrelated to the "equipment grounding" conductors.

I haven't seen this specific modification before.

What think ye?

You haven't given enough information for me to have an opinion one way or the other.

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. . . Yeah, except the answer is complete crap. . .

I disagree. It's one of the clearer explanations I've heard. MD Shunk is a very smart guy who knows his stuff inside out.

What, in particular, do you disagree with?

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Jim, if it helps, the service entry cable, through the modification, simply has two successive main disconnects - one added outside, and the original main disconnect in the service panel.

The new main disconnect, panel is bonded and grounded to the original grounding rod for the original service panel, and the original service panel remains bonded and grounded to that same rod. I hope that makes sense.

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Thanks John. That's what I thought (neutrals/grounds), but since electrical isn't my forte, I thought I'd bounce it off the brain trust, before I go down that road.

And, you feel the ground conductor from the main panel to the rod should go away, now that it's become a sub-panel? That was the other thing that I suspected was the case.

First of all, I'm not a trained electrician and I only know a smattering of the NEC rules, but ..Jim K will correct me if I flub this.... The grounding conductor should go only to the panel containing the main disconnect. The arrangement you describe results in parallel paths the earth, and that is to be avoided. Easily fixed.

And Douglas, Jim Port, or MD Shunk can correct me if I'm wrong, but I don't see a problem with it. As long as the sub panel has two hots, a neutral, and an equipment grounding conductor going back to the service panel, I don't see any harm in also having a conductor between the sub panel's grounding terminal and the ground rod. During normal day-to-day operation of the system no current should ever flow to or from that rod. During a fault, the equipment ground will come into play -- still no current on the rod. The only time current should flow on that rod is if there's a nearby lightning strike or surge, in which case I don't see any issue with parallel paths.

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Jim, if it helps, the service entry cable, through the modification, simply has two successive main disconnects - one added outside, and the original main disconnect in the service panel.

Will one of these disconnects cut power to the other?

The new main disconnect, panel is bonded and grounded to the original grounding rod for the original service panel, and the original service panel remains bonded and grounded to that same rod. I hope that makes sense.

Yes. But is there a 4-wire feeder between the two panels that you describe?

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. . . Yeah, except the answer is complete crap. . .

I disagree. It's one of the clearer explanations I've heard. MD Shunk is a very smart guy who knows his stuff inside out.

What, in particular, do you disagree with?

I disagree with the premise that one can rely on mixing valves as a bonding jumper.

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Jim, if it helps, the service entry cable, through the modification, simply has two successive main disconnects - one added outside, and the original main disconnect in the service panel.

Will one of these disconnects cut power to the other?

The new main disconnect, panel is bonded and grounded to the original grounding rod for the original service panel, and the original service panel remains bonded and grounded to that same rod. I hope that makes sense.

Yes. But is there a 4-wire feeder between the two panels that you describe?

Yes and yes.

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. . . Yeah, except the answer is complete crap. . .

I disagree. It's one of the clearer explanations I've heard. MD Shunk is a very smart guy who knows his stuff inside out.

What, in particular, do you disagree with?

I disagree with the premise that one can rely on mixing valves as a bonding jumper.

Why?

What about the body of the water heater?

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I saw double as well no long ago.

There was 1 ground wire on the main water valve and another one on the water heater valve.

That wasn't a "ground" it was a bonding cable. Get a copy of Electrical Inspection of Existing Dwellings - 2001 by Douglas Hansen. Read it from cover-to-cover, go out and look at about 10 or 20 panels and systems, read it again from cover to cover, go out and look at about 10 or 20 more panels, repeat. Somewhere around the third read some of it will start to stick and make sense. By the fourth read you'll have it.

ONE TEAM - ONE FIGHT!!!

Mike

Nah this bonding cable is rare in Quebec, so i'll skip that one.

You see, instead of reading a book 4 times, I rather surf the internet! You can really find anything.... really! It's pretty interesting! When you have a minimal degree of education, let say university degree, you can search whatever you want! here's an example on your bonding cable.

Hi Everyone,

I got a question. In a 20flat I inspected yesterday, I saw a grounding wire being bonded to a cold water pipe supplying a water heater. The wire was attached about 3.5 feet away. First of all, is it OK? Second, should hot, cold and gas piping at the water heater be bonded together. Is jumper necessary? It's just I've never seen this kind of grounding to a water pipe.

What you likely saw was "bonding", and it's both required and a good idea. In the event that something should energize the pipework in each unit, there will be a good ground fault path back to the panel to allow the breaker to trip (mitigating the hazard). As long as one pipe (either hot or cold) is bonded, the other one is likely bonded as well via the water heater and various mixing valves like on the kitchen sink, bath lav, and shower valve. Gas pipe bonding is usually accomplished by factory connections that already exist in gas appliance that utilize both gas and electricity such as warm air furnaces. No extra bonding is normally required for gas piping, but doesn't hurt a thing if a guy adds some.

Reference: http://www.nachi.org/forum/f19/groundin ... ter-27765/

(Remaining comments moderated.)

So you know how to google.

Do you have any idea what any of it means? I'm sure that I could google neurosurgery techniques but I doubt that without an education in how a brain works I'd be able to truly grasp what the neurosurgeon is saying and why.

ONE TEAM - ONE FIGHT!!!

Mike

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. . . Yeah, except the answer is complete crap. . .

I disagree. It's one of the clearer explanations I've heard. MD Shunk is a very smart guy who knows his stuff inside out.

What, in particular, do you disagree with?

I disagree with the premise that one can rely on mixing valves as a bonding jumper.

Why?

What about the body of the water heater?

The mixing valve itself can be relied to be an effective bonding "jumper", but the connections certainly are questionable. Almost all mixing valves are installed with flexible connectors, many of which aren't conductive.

My Danze tub filler came with silicone hoses permanently crimped in place.

The body of the water heater bonds the hot and cold- except when there is no water heater in place - replacement and winterization are two likely scenarios.

And, §250.8 talks about soldered connections:

250.8 Connection of Grounding and Bonding Equipment.

(A) Permitted Methods. Grounding conductors and bonding jumpers shall be connected by one of the following means:

(1) Listed pressure connectors

(2) Terminal bars

(3) Pressure connectors listed as grounding and bonding equipment

(4) Exothermic welding process

(5) Machine screw-type fasteners that engage not less than two threads or are secured with a nut

(6) Thread-forming machine screws that engage not less than two threads in the enclosure

(7) Connections that are part of a listed assembly

(8) Other listed means

(B) Methods Not Permitted. Connection devices or fittings that depend solely on solder shall not be used.

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The mixing valve itself can be relied to be an effective bonding "jumper", but the connections certainly are questionable. Almost all mixing valves are installed with flexible connectors, many of which aren't conductive.

Have you ever seen a shower mixing valve with flexible connectors?

My Danze tub filler came with silicone hoses permanently crimped in place.

Oddball scenario.

The body of the water heater bonds the hot and cold- except when there is no water heater in place - replacement and winterization are two likely scenarios.

Except that 99% of the time, there's still a shower mixing valve in the system somewhere.

And, §250.8 talks about soldered connections:

250.8 Connection of Grounding and Bonding Equipment.

(A) Permitted Methods. Grounding conductors and bonding jumpers shall be connected by one of the following means:

(1) Listed pressure connectors

(2) Terminal bars

(3) Pressure connectors listed as grounding and bonding equipment

(4) Exothermic welding process

(5) Machine screw-type fasteners that engage not less than two threads or are secured with a nut

(6) Thread-forming machine screws that engage not less than two threads in the enclosure

(7) Connections that are part of a listed assembly

(8) Other listed means

(B) Methods Not Permitted. Connection devices or fittings that depend solely on solder shall not be used.

Are you recommending the installation of jumpers across every soldered fitting in a plumbing system?

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The mixing valve itself can be relied to be an effective bonding "jumper", but the connections certainly are questionable. Almost all mixing valves are installed with flexible connectors, many of which aren't conductive.

Have you ever seen a shower mixing valve with flexible connectors?

I've seen hundreds stubbed in w/ pex

Quote: My Danze tub filler came with silicone hoses permanently crimped in place.

Oddball scenario.

I thought so too, but the lav faucets were the same way

Quote: The body of the water heater bonds the hot and cold- except when there is no water heater in place - replacement and winterization are two likely scenarios.

Except that 99% of the time, there's still a shower mixing valve in the system somewhere.

unless it's stubbed in w/ pex

Quote: And, §250.8 talks about soldered connections:

250.8 Connection of Grounding and Bonding Equipment.

(A) Permitted Methods. Grounding conductors and bonding jumpers shall be connected by one of the following means:

(1) Listed pressure connectors

(2) Terminal bars

(3) Pressure connectors listed as grounding and bonding equipment

(4) Exothermic welding process

(5) Machine screw-type fasteners that engage not less than two threads or are secured with a nut

(6) Thread-forming machine screws that engage not less than two threads in the enclosure

(7) Connections that are part of a listed assembly

(8) Other listed means

(B) Methods Not Permitted. Connection devices or fittings that depend solely on solder shall not be used.

Are you recommending the installation of jumpers across every soldered fitting in a plumbing system?

Nope, the way I understand it is the connection bonding the system can't rely on solder only. I guess the point I'm trying to make is that relying on removable appliances or on fixtures to act as a bonding jumper is , well, unreliable.

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