Neutral bond at Siemens panel

[Michael Thomas]

Siemens panel, load-side in condo.

Does anyone know if this screw is bonding to the panel, or is it "backed out" and not making contact?

Also, is there any requirement that bonding screws be completely removed if in not service equipment?

Also, is "bonding screw" the correct term


Thanks

[A.D. Miller]

Michael: Is this the main distribution panelboard or a remote distribution panelboard?

[Michael Thomas]

Michael: Is this the main distribution panelboard or a remote distribution panelboard?

It's a load side panel ("sub panel") in a condo, service disconnect is at the meter cabinet, that's why I need to know if that screw is bonding to the panel.

[Richard Moore]

Siemens panel, load-side in condo.

Does anyone know if this screw is bonding to the panel, or is it "backed out" and not making contact?

Assuming that's the screw that came with the panel, then my best guess is that it's pulled out far enough to not be in contact.


Also, is there any requirement that bonding screws be completely removed if in not service equipment?

Common sense! The only threads are at the metal at the back of the panel. The screw is just lying there loose and could easily be pushed into contact. Take it out.


Also, is "bonding screw" the correct term

Correct enough although Jerry probably has some term that includes submarines. ;)

[ken horak]

I would venture to say that bonding screw is not making contact but one can not be 100% sure. I would suggest that the bonding screw be totally removed and discarded. This way one would be 100% positive.
A good installer would have thrown that bond screw away when the subpanel was installed.
An even better electrical inspector would have made sure that the screw was not installed or left laying in the bottom of the panel.
Why not just leave it in the bottom of the panel ? Because some less knowledgeable person would see it and install it creating a parallel path to ground,which all know is a bad thing.

[A.D. Miller]

I would venture to say that bonding screw is not making contact but one can not be 100% sure. I would suggest that the bonding screw be totally removed and discarded. This way one would be 100% positive.
A good installer would have thrown that bond screw away when the subpanel was installed.
An even better electrical inspector would have made sure that the screw was not installed or left laying in the bottom of the panel.
Why not just leave it in the bottom of the panel ? Because some less knowledgeable person would see it and install it creating a parallel path to ground,which all know is a bad thing.

KH: Agreed.

[bruce m graham III]

I would like to see more insulation removed from the neutral conductor, it looks like there is insulation under the lug screw.

[Jerry Peck]

Being as you are in a condo and are looking at the panel there, we KNOW it is not service equipment, it is just a distribution panel / loadcenter in which the neutral is required to be isolated from ground.


Also, is there any requirement that bonding screws be completely removed if in not service equipment?

Common sense says to remove it so it cannot accidentally make contact with the grounded back of the enclosure, the instruction on the panel may also state to remove the screw, which does not mean 'part way' as the screw is not "removed" - the screw is still "there".


Also, is "bonding screw" the correct term

Bonding screw is correct.

[Michael Thomas]

Assuming I was inclined to just get out my meter and find out, what would be the best measurement points, and real-world what should I expect to find?

[Jerry Peck]

Assuming I was inclined to just get out my meter and find out, what would be the best measurement points, and real-world what should I expect to find?

Measure voltage first. Measure the voltage between the neutral terminal bar and ground in that panel.

Now measure from the screw to ground and from the screw to neutral.

If no voltage is present you can measure continuity neutral to the screw and then the screw to ground.

Real world could possibly be a couple of volts neutral to ground (probably 5 volts max), but whatever it is, that is the voltage you would want to seen screw to ground. I would expect far less than a couple of volts neutral to ground - I would like to see milli-volts or less neutral to ground. Measuring -0- volts neutral to ground would be ideal.

Never measure continuity if there is voltage present.

[Douglas Gross]

Does anyone see a ground feeder wire here?
The pictures don't show the equipment grounding bars.

[Jamey Tippens]

To me, it looks like the equipment bonding strap has been removed from behind the screw, and the only contact that the screw could reach would be the plastic insulator.
Jamey

[Joe Laurieri]

Although I enjoy the healthy banter.

One would figure HI's have and should use some basic common sense.

In this case it seems pretty simple if it's needed it should be used and if not required and poses a potential risk then remove it.

Voila......

I would remove it and tape it in the panel or to the back of the front plate for future us if required.

Explain it to your client.....I,m sure they will appreciate your assistance and maybe a ggod referral.

[Jerry Peck]

One would figure HI's have and should use some basic common sense.

In this case it seems pretty simple if it's needed it should be used and if not required and poses a potential risk then remove it.


HIs do use common sense, which is why WE DO NOT REMOVE things like that.


I would remove it and tape it in the panel or to the back of the front plate for future us if required.

Hopefully, then, you are a licensed electrician as you are acting as a licensed electrician when you remove it.

See "common sense" is not to screw around with things you are not licensed to do, and, for home inspectors, that means "REPORTING" what you find, not "trying to fix something".

Clients recognize professionals by what they say and do :D , and for a 'professional HI' to go around fixing things, or trying to fix things, simply makes them an unlicensed tradesperson. :eek:

[Jerry Peck]

To me, it looks like the equipment bonding strap has been removed from behind the screw, and the only contact that the screw could reach would be the plastic insulator.
Jamey


If you look at the diagram which was also posted you will see that the screw is simply screwed into the back of the panel to become the bonding screw. Otherwise the diagram would show a strap and show where the strap is mounted to the enclosure - and it shows neither. The photo also does not show a mounting hole for a bonding strap mounting screw to the enclosure.

[Michael Thomas]

The interior of the panel, in detail:

http://paragoninspects.com/images/temp/090516-1-panel-wide.jpg

Developer picked a great location, as well......

[Jamey Tippens]

You can ignore my post from a few days ago. I inspected a panel exactly like this one yesterday and the screw does bond by contacting the back of the panel. In the one I inspected, the screw had been removed, which was entirely appropriate since it is a subpanel.

[Jerry Peck]

the screw had been removed, which was entirely appropriate since it is a subpanel.

I see that some people still do not understand that an "electric panel", a so called "main panel" and a so called "sub panel" are all, yes, get this, are all ... drum roll ... are all wired exactly the same.

Therefore, removing that bonding screw screw from ground is only necessary when the electrical equipment (that "panel") is not "service equipment", but is simply just a "panel".

[Jamey Tippens]

Thanks, Jerry
You're exactly right of course, and I know better than to call it a subpanel. Mea culpa.

[ken horak]

Surprised no body commented on the panel being located in a clothes closet.
Violation of NEC Article 240.24 (D)
Not in the vicinity of Easily Ignitable Materials:
Overcurrent devices shall not be located in the vicinity of easily ignitable material,such as clothes closets.

[Douglas Gross]

Perhaps I'm the only one who isn't seeing this, but shouldn't we be seeing a large EGC feeder coming into this panel?
Or is there something with the Chicago code that just allows the conduit bond to suffice?

Sorry if I'm overlooking something obvious here.

[Jerry Peck]

Perhaps I'm the only one who isn't seeing this, but shouldn't we be seeing a large EGC feeder coming into this panel?
Or is there something with the Chicago code that just allows the conduit bond to suffice?

Sorry if I'm overlooking something obvious here.

Douglas,

The NEC allows the following to be used as equipment grounding conductors: (bold and underlining are mine)
- 250.118 Types of Equipment Grounding Conductors.
- - The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:
- - - FPN: For effective ground-fault current path, see 250.2 Definition.
- - - (1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and in the form of a wire or a busbar of any shape.
- - - (2) Rigid metal conduit.
- - - (3) Intermediate metal conduit.
- - - (4) Electrical metallic tubing.
- - - (5) Listed flexible metal conduit meeting all the following conditions:
- - - - a. The conduit is terminated in listed fittings.
- - - - b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
- - - - c. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
- - - - d. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.
- - - (6) Listed liquidtight flexible metal conduit meeting all the following conditions:
- - - - a. The conduit is terminated in listed fittings.
- - - - b. For metric designators 12 through 16 (trade sizes through ½), the circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
- - - - c. For metric designators 21 through 35 (trade sizes ¾ through 1¼), the circuit conductors contained in the conduit are protected by overcurrent devices rated not more than 60 amperes and there is no flexible metal conduit, flexible metallic tubing, or liquidtight flexible metal conduit in trade sizes metric designators 12 through 16 (trade sizes through ½) in the grounding path.
- - - - d. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
- - - - e. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.
- - - (7) Flexible metallic tubing where the tubing is terminated in listed fittings and meeting the following conditions:
- - - - a. The circuit conductors contained in the tubing are protected by overcurrent devices rated at 20 amperes or less.
- - - - b. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
- - - (8) Armor of Type AC cable as provided in 320.108.
- - - (9) The copper sheath of mineral-insulated, metal-sheathed cable.
- - - (10) Type MC cable where listed and identified for grounding in accordance with the following:
- - - - a. The combined metallic sheath and grounding conductor of interlocked metal tape–type MC cable
- - - - b. The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube-type MC cable
- - - (11) Cable trays as permitted in 392.3 and 392.7.
- - - (12) Cablebus framework as permitted in 370.3.
- - - (13) Other listed electrically continuous metal raceways and listed auxiliary gutters.
- - - (14) Surface metal raceways listed for grounding.

Chicago runs everything in conduit, so 2), 3), and 4) would be allowed as the equipment grounding conductor. And not just in Chicago. And, yes, the proper knockouts and grounding bushings would be required to be used.

[Douglas Gross]

Douglas,

The NEC allows the following to be used as equipment grounding conductors: (bold and underlining are mine)
- 250.118 Types of Equipment Grounding Conductors.
- - The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:
- - - FPN: For effective ground-fault current path, see 250.2 Definition.
- - - (1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and in the form of a wire or a busbar of any shape.
- - - (2) Rigid metal conduit.
- - - (3) Intermediate metal conduit.
- - - (4) Electrical metallic tubing.
- - - (5) Listed flexible metal conduit meeting all the following conditions:
- - - - a. The conduit is terminated in listed fittings.
- - - - b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
- - - - c. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
- - - - d. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.
- - - (6) Listed liquidtight flexible metal conduit meeting all the following conditions:
- - - - a. The conduit is terminated in listed fittings.
- - - - b. For metric designators 12 through 16 (trade sizes through ½), the circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
- - - - c. For metric designators 21 through 35 (trade sizes ¾ through 1¼), the circuit conductors contained in the conduit are protected by overcurrent devices rated not more than 60 amperes and there is no flexible metal conduit, flexible metallic tubing, or liquidtight flexible metal conduit in trade sizes metric designators 12 through 16 (trade sizes through ½) in the grounding path.
- - - - d. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
- - - - e. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.
- - - (7) Flexible metallic tubing where the tubing is terminated in listed fittings and meeting the following conditions:
- - - - a. The circuit conductors contained in the tubing are protected by overcurrent devices rated at 20 amperes or less.
- - - - b. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
- - - (8) Armor of Type AC cable as provided in 320.108.
- - - (9) The copper sheath of mineral-insulated, metal-sheathed cable.
- - - (10) Type MC cable where listed and identified for grounding in accordance with the following:
- - - - a. The combined metallic sheath and grounding conductor of interlocked metal tape–type MC cable
- - - - b. The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube-type MC cable
- - - (11) Cable trays as permitted in 392.3 and 392.7.
- - - (12) Cablebus framework as permitted in 370.3.
- - - (13) Other listed electrically continuous metal raceways and listed auxiliary gutters.
- - - (14) Surface metal raceways listed for grounding.

Chicago runs everything in conduit, so 2), 3), and 4) would be allowed as the equipment grounding conductor. And not just in Chicago. And, yes, the proper knockouts and grounding bushings would be required to be used.

Well I certianly see your point with the conduit. It just seems a bit "mickey-mouse" to me, considering a situation where the feeders enter the panel not in conduit - it would require a large EGC (usually 2 sizes less than the line conductors, I believe).
So just the EMT and a grounding bushing... It just looks like a lot more impedance than a thick, bare, copper wire comming into the panel. Just my impression.
Go codes!

[Jerry Peck]

It just seems a bit "mickey-mouse" to me,

Not "Mikey Mouse" at all.


considering a situation where the feeders enter the panel not in conduit

Where do you see that at in that photo?

Or are you talking about another installation which does not use conduit? If so, then, yes, an equipment grounding conductor would be required, including for PVC conduit, but that is another discussion altogether.


- it would require a large EGC (usually 2 sizes less than the line conductors, I believe).

It use to be a rule-of-thumb that the neutral (not the equipment grounding conductor) was allowed to be 2 sizes smaller, never in the code though - at least it was that way where I was at the time. The code requires the neutral to be sized for its loads, which, with all the harmonics today, sometimes requires the neutral to actually be sized larger than the phase hot conductors.

The equipment grounding conductor is to be sized in accordance with Table 250.122.

Some examples from Table 250.122 are:
#14 copper/15 amp breaker = #14 copper EGC
#12 copper/20 amp breaker = #12 copper EGC
#10 copper/30 amp breaker = #10 copper EGC
#8 copper/40 amp breaker = #10 copper EGC
#6 copper/60 amp breaker = #10 copper EGC
- Note, though, that the EGC size is not based on the phase conductor size, but on the overcurrent protection size ... sort of ... if the phase conductor size is increased (for whatever reason), the EGC is size is to be increased proportionally.

[Brian Robertson]

Is that panel OK buried in the wall like that? Thanks.:)

[Jerry Peck]

Is that panel OK buried in the wall like that? Thanks.:)


You mean "flush mounted"? Yes, either "flush mounted" or "surface mounted", depends on the cover used.

For "surface mounted" the cover bends around the enclosure, for "flush mounted" the cover extends out over the wall surface.

If you mean "buried" as in "buried in clothes in a clothes closet", then, no - no electrical panel is allowed in clothes closets.

[Brian Robertson]

Yes I meant flush mounted. So it depends on if it was designed for that then. Thanks for the reply!!

[Jerry Peck]

Yes I meant flush mounted. So it depends on if it was designed for that then. Thanks for the reply!!

As far as I know, all residential electrical panels are designed for either mounting, depending on which cover you order for it - but the enclosure is suitable for either mounting (trying to recall a modern one which was not ... ??? ... ).