Grounding Metal Outlet Boxes and Isolated Ground Receptacles


Just installed six really nice separate dedicated 20 amp lines (with 6 awg) for my new dedicated listening room.  Decided to use heavy metal outlet boxes so that I could make my six Furutech Receptacles as strong and sturdy as possible.  I also had my electrician run 4-wire 6 agw to the boxes so that we could have one ground wire to the metal receptacle box and then a separate ground wire to the isolated ground screw on the Furutech.

I sent some photos of the setup to a friend of mine (who just happens to be an electrical engineer) and he raised an the issue that since my Furutech Receptacles are metal and they will be screwed into the metal box with metal screws, then we have effectively now tied the two separate grounds together!  Help!  Is that a bad idea?   Is having the box and receptacle setup in this way going to cause issues once my gear is in place; ground loop hums, etc?






stickman451
bimmer528 said:
i am in Chicago, very strict here on what can and can’t be acccepted.
That’s an understatement.

I assume this is current electrical code for Chicago.

Chicago IL Residential Electrical Code.

RESIDENTIAL WIRING:

A.

All wiring changes or additions to electrical systems in residences previously constructed should be rigid or electrical metallic tubing where possible and all basements should be in conduit.

1.

Where necessary to fish through existing partition, BX or flexible conduit may be used and must terminate within twenty-four inches (24") of its entrance into any basement or crawl space area.

2.

Where a question exists as to methods or materials used, the ruling of the Electrical Inspector shall govern.

3.

All conduit on or below grade, shall be galvanized rigid conduit PVC (Minimum Schedule 40 Poly Vinyl Chloride), rigid conduit to be used in concrete only.

(No. I.M.C. Steel) burial depth a minimum of twenty-four inches (24").

B.

All wiring systems installed in new residences shall be in rigid conduit or electrical metallic tubing.

1.

Junction boxes may not be installed in inaccessible or concealed locations. This does not exclude use of said boxes in basements, crawl spaces or attics. Junction boxes may not be installed under overhang or decorator or soffits.

2.

Said conduits shall be installed on what is known as the "loop system" and shall be completed between the approved outlets, having not more than four (4) right angle or equivalent bends including those at the outlets.

C.

All service entrance conductors shall be installed in one and one-fourth inch (1¼") conduit or larger if required. All new services must be in rigid metal conduit, meter sockets and panels are to be installed with butterfly bolt or anchors and have a branch circuit panel with a minimum capacity of sixteen (16) poles.

1.

Underground services shall be installed as approved by the local public utility rules, as filed with the Illinois Commerce Commissioner and must be at least two (2) No. 2 gauge wire and one No. 4 wire for neutral conductor. For direct burial, wire approved for that use must be installed.

2.

There shall be no splices in any wire approved for direct burial.

3.

Connections between outside meter fittings and inside service connecting device must be run in outside of building as much as possible and be installed in conduit without the use of concealed fittings.

4.

For a single-family dwelling, the service disconnecting means shall have a rating of not less than one hundred (100) amps. Service entrance conductors shall be not less than two (2) No. 2 gauge copper or approved 4 gauge copper wire, approved for use.

5.

Two-family houses shall have a one hundred (100) amp disconnecting means for each family unit. Service entrance conductors for two-family houses shall not be less than 3/0 gauge copper wire and one No. 1/0 gauge copper for neutral wire. For three (3) to six (6) more meters the service riser will have to carry a one hundred (100) amp for each meter.

D.

In all cases service entrance conductors must be adequate for the connected load.

E.

Grounding for combination systems and equipment, grounding to be done with No. 4-B & S gauge, copper or equivalent current-carrying capacity; wire run directly from neutral in service disconnecting or distribution box to the street side of the water shut-off valve, where said valve is inside of the building.

1.

In all homes without basements, of slab or other construction, entry of water service or shut-off valve shall be the location of ground locations.

2.

On approved two-jaw type, one ground clamp of metal similar to that attached shall be used.

3.

Said ground wire must be installed under basement concrete floor.

4.

Ground wire may be solid, stranded bare, insulated or of weather-proof type No. 4.

5.

Electrical ranges may be grounded to the neutral conductor. No other cabinet or appliance can be grounded to the neutral conductor.

6.

Bare neutral can be used only on service entrance as far as supply disconnect device.

F.

Rooms not now wired or additions to homes now built, shall be done by the rules covered herein and also shall have at least one circuit for each five hundred (500) square feet of area for general lighting purposes.

G.

Each single-family home or separate apartment shall have its own disconnecting device located as determined by the 1993 edition and later editions of the National Electrical Code and the Electrical Inspector.

H.

Each single-family home or separate apartment of multiple dwelling occupancies shall have at least two-appliance circuit, wired with No. 12 B & S gauge wire and may be fused at twenty (20) amperes, to supply the receptacles located in kitchens, dining rooms, dinettes, breakfast room, pantry, utility rooms and laundry. No lighting shall be installed on this circuit.

1.

Outlets for electrical clocks cannot be on this circuit.

2.

Receptacles shall be installed on the wall, two feet (2’) from the laundry tray in the laundry room and shall be a three-pole type suitable for grounding purposes. Recommended use of one of the types now available and suitable to receive present two-prong type of attachment plug now in general use. Receptacles or switch installations in garage areas must be mounted not less than fifty inches (50") from finished floor.

3.

Combination light and receptacle outlets may not be used in place of laundry outlets required.

4.

Certain other laundry equipment, such as dryers, may be required to be on separate circuits according to the loads used and judgment of the Electrical Inspector.

I.

Heating or air conditioning systems are to be on separate circuits and to a switch installed on or near the equipment disconnecting ungrounded conductors.

If

No. 12 size conductors are used and less than twenty-five feet (25’) in length, then the sub-main terminals may be used, provided a fuse-type switch is used at the equipment.

J.

No circuit wired with No. 12 B & S gauge wire should have more than thirteen (13) outlets or receptacles for general lighting purposes connected thereto.

K.

No circuit wired with No. 14 B & S gauge wire should have more than ten (10) outlets or receptacles for general lighting purposes connected thereto.

L.

In any case a circuit shall be able to carry any load connected thereto.

M.

All outdoor or entrance outlets should have an outlet box suitably installed and waterproofed, must be on ground fault.

N.

Ceiling joists may not be notched for installation of conduit without written permission of the Electrical Inspector. Ceiling joists or studding may be drilled for conduit installation.

O.

All conduit run on top of the ceiling joist shall be run straight and at right angles to the joist and strapped thereto. Conduit run parallel to the ceiling joist shall be set down beneath the top edge of same.

P.

All exposed runs in basements or other locations should be installed in a neat and workmanlike manner.

Q.

Ceiling joist shall be notched one-eighth inch ( 1/8 ") for bar hanger installation.

R.

All outlets for general lighting purposes shall be one and one-half inches (1½") in depth and three and three-fourths inches (3¾") in diameter of 1900 type of box.

S.

Switch and receptacle box shall be 1900 or four inch (4") square by one and one-half inch (1½") type of box set flush with studding.

T.

On dry wall construction a flat type of outlet cover box shall be used. Otherwise all covers for outlet boxes shall be at least one-half inch (½") in depth.

U.

Where three and three-fourths inch (3¾") octagon box is used for ceiling outlets, the shallow offset type of box shall be used to bring the outlet box to the edge of the rock-lath or other material.

V.

The box should be installed to come within one-fourth inch (¼") of the finished surface.

W.

Wires not to be drawn into conduit until wall finishes are applied or all mechanical work is completed without written consent of the Electrical Inspector.

X.

Hot travelers for three-way switches are not allowed.

Y.

All fuses shall be of the approved time delay type "S" or breakers.

Z.

Metal fixtures installed over kitchen sinks or in bathrooms shall be mounted so as to be grounded and controlled by wall switch.

AA.

Outlets in closets shall be installed in the ceiling close to the door. Brackets can be used only over doorways.

BB.

All circuit splices shall be made with approved connectors.

CC.

At least one wall receptacle for each twelve feet (12’) of lineal wall space as measured horizontally around the room at the baseline, including all door or window openings in all living rooms, bedrooms, dining rooms, library rooms and kitchens. Receptacles not to be installed in floor unless of the approved type and must be within two feet (2’) of the wall to be counted as one required above.

DD.

All boxes mounted back to back to be firmly bolted together or nippled between, to insure continuity of ground. All connections, couplings, locknuts or bushings to be set up tight.

EE.

All recessed lighting outlets to be connected with approved wire suitable for the purpose and have temperature rating of one hundred fifty degree centigrade (150°C). Not more than one conduit may be run to any direct or recessed lighting fixture unless run to a junction box outside of fixture in the manner approved by the Electrical Inspector.

FF.

Installation of household electric ranges of not more than twelve and three-fourths (12¾) K.W. capacity may be installed in three-fourths inch (¾") conduits using two (2) No. 8 gauge and one No. 10 gauge wire.

GG.

Porcelain pull-chain type of fixtures must have insulator between pull-chain and attached chain. No grass shell type of sockets allowed in basement or other damp areas. All drop cords shall be of the type approved for locations used.

HH.

Three-wire branch circuits are approved, providing the conductors are of different colors and other than white and providing they are so connected as to apply two hundred thirty (230) volts across the phase wires. Otherwise two-wire circuits must be run. If more than one three-wire circuit is run in the same conduit, then all underground conductors should be of different colors.

II.

In general, rules and regulations included in the 1993 Edition and later editions of the National Electrical Code are herein implied.

https://www.municode.com/library/il/north_chicago/codes/code_of_ordinances?nodeId=TIT12BURE_CH14ELRE...

The city Electrical Department is still following some of the electrical standards of the 1993 NEC, (National Electrical Code). I find that incredible they have not kept up with NEC since 1993. LOL, NEC is updated every 3 years.

The mandated requirement that rigid conduit, EMT, must be used in single family dwellings, houses, in 2016 is just plain nuts.

As an outsider of Chicago looking in it appears to me the central governing body, power, of Chicago is/has been for years, bought off by the Electrical Contractor Lobby. As I read some of the code requirements I seen unnecessary $$$$$ in added material and labor costs that drives up the building cost of a new home, built in Chicago.

No mention what so ever of AFCI (Arc Fault Circuit Interrupter) protection any where in the code. Of course in 1993 they did not exist. Not until 1999 did NEC first speak of branch circuit arc fault protection. In 2001 NEC required AFCI protection on all branch circuits feeding receptacles in bed rooms. By NEC 2008 their use was expanded followed in other areas of the home. NEC 2011 even more expansion, and even more in NEC 2014. Electrical acing is one of the biggest causes of electrical fires in homes.

My guess is the governing body of Chicago is aware of the NEC requirement for AFCI protection in residential units. They just don’t want the general public to know. Why? How could they then justify the mandated requirement for rigid conduit in homes for all branch circuit wiring? $$$$$$

http://structuretech1.com/new-electrical-safety-requirement-afci-receptacles/

http://www.codecheck.com/cc/ccimages/PDFs/AFCIsComeOfAge.pdf

Jim
.
EDIT:

jea48 said:
The city Electrical Department is still following some of the electrical standards of the 1993 NEC, (National Electrical Code). I find that incredible they have not kept up with NEC since 1993. LOL, NEC is updated every 3 years.
That may not be accurate.

From the supplied Link,
In general, rules and regulations included in the 1993 Edition and later editions of the National Electrical Code are herein implied.
bimmer528,

Is AFCI protection required in new homes built in Chicago today?

Are they required if new branch circuits are added in an existing home?
For the rewire of an older home?


Manditory with the conjunction of any gfci outlet. Your talking in newer builds money adding each of those to a panel. All must have dedicated neutral and cannot be shared. I've seen debate there but it's my understanding the faults won't work correctly unless dedicated. 

any remodel on older work must also incoperate same or your grandfathered in.

all interior raceways must be emt or rigid. Why run rigid when yiu can use emt. 

You can can whip up to 5 feet only for lighting. Some inspectors will require a ground with that use. 

As as far as I know all exterior work must be rigid only. 

also depends on the inspector and what that one thing they look for... you know how it is. 

Chicago is lunicy and just plain overkill. 


bimmer528,

A GFCI breaker cannot be used on multi wire branch circuits. ( The neutral is shared on multi wire branch circuits) The GFCI breaker will just trip open the second any load is connected to the other hot circuit wire of the multi wire branch circuit.
The hot and neutral connected load to the GFCI must be balanced. If an imbalance is detected on either line the breaker will trip open.

In the case of a 120V circuit where a GFCI breaker is used each 120V circuit has to have its’ own neutral conductor. Both the Hot, ungrounded conductor, and the neutral, the grounded conductor, of the branch circuit connects to the single pole GFCI breaker. (Depending on the electrical panel, the GFCI breaker used may have an insulated white neutral pigtail wire that connects to the neutral bus in the panel, or the breaker may be the type that connects directly to special neutral bar, rail.)
I personally prefer using a GFCI duplex receptacle over a GFCI breaker.

In the case of a multi wire branch circuit where GFCI protection is needed, or required per code, example in a kitchen above counter tops, A GFCI duplex receptacle is used.

In my previous post I asked you about if Chicago requires AFCI (Arc Fault Circuit Interrupter) protection in dwelling units.

2014 NEC requires the use of CAFI (Combination Arc Fault Interrupters) on all 120V 15 amp and 20 amp lighting and receptacle outlet branch circuits in dwelling units for new construction, as well as a newly installed branch circuit/s in existing dwelling units.

The CAFI device can be a CAFI breaker or a CAFI duplex receptacle device. The CAFI will trip open, breaking the circuit, if it detects series or parallel arcing.

A GFCI’s purpose, function, is to protect life from electrocution. If the sensing unit in the device detects more than 5 to 6 ma of ground fault current from the hot to an earth grounded object the unit will trip open. (The earth grounded object could be the safety equipment grounding conductor, or any other earth grounded object the person, or pet, may come into contact with while in contact at the same time with the HOT conductor.)
(NOTE: The actual ground fault circuit is from the HOT conductor >> through the person’s body >> out to the earth grounded contacted object >> to the electrical service’s earth grounded service neutral conductor. A complete closed circuit.)

A CAFI’s purpose, function, first priority is to protect property from an electrical fire caused from an electrical arcing event. By doing so ultimately the CAFI may protect life if a person or pet is in the home at the time of the electrical arcing event.

Like the GFCI breaker a CAFI breaker cannot be used on a multi wire branch circuit. Like the GFCI breaker both the Hot and neutral conductors of the branch circuit connects directly to the breaker.

Has there been problems with AFCI/CAFI breakers nuisance tripping? yes... Not so much now though. Most of the problems were because of improper installation of the branch circuit wiring and improper connections in electrical outlet boxes.
Some problems with nuisance tripping with the early AFCI breakers was because of interactions with some lighting dimmers. Lutron being one such dimmer.

As always, the AHJ has the final say...
.
I was asked by my local inspector or should I say forced to add Afci to all my gfci dedicated runs.  Nevermind bedrooms/living areas as they are normally intended for where homes do not have smoke carbon detects ran in series..  

you asked if it was maditory. It was for me but would depend on the inspector from what I've seen.  What cannot be ignored unfortunately is basically the amount of labor required to complete jobs satisfactory. 

Cheers ;)