ground the outlet or not??

bnut311 said:
There’s no 60/120V systems in this country.

NEC, National Electrical Code.

Quote from Link below.

ARTICLE 647 Sensitive Electronic Equipment

647.1 Scope. This article covers the installation and wiring of separately derived systems operating at 120 volts line-to-line and 60 volts to ground for sensitive electronic equipment.

647.3 General. Use of a separately derived 120-volt single-phase 3-wire system with 60 volts on each of two ungrounded conductors to a grounded neutral conductor shall be permitted for the purpose of reducing objectionable noise in sensitive electronic equipment locations, provided the following conditions apply:

(1) The system is installed only in commercial or industrial occupancies.

(2) The system’s use is restricted to areas under close supervision by qualified personnel.

(3) All of the requirements in 647.4 through 647.8 are met.

647.4 Wiring Methods

(A) Panelboards and Overcurrent Protection. Use of standard single-phase panelboards and distribution equipment with a higher voltage rating shall be permitted. The system shall be clearly marked on the face of the panel or on the inside of the panel doors. Common trip two-pole circuit breakers or a combination two-pole fused disconnecting means that are identified for use at the system voltage shall be provided for both ungrounded conductors in all feeders and branch circuits. Branch circuits and feeders shall be provided with a means to simultaneously disconnect all ungrounded conductors.

(B) Junction Boxes. All junction box covers shall be clearly marked to indicate the distribution panel and the system voltage.

(C) Conductor Identification. All feeders and branch-circuit conductors installed under this section shall be identified as to system at all splices and terminations by color, marking, tagging, or equally effective means. The means of identification shall be posted at each branch-circuit panel-board and at the disconnecting means for the building.

(D) Voltage Drop. The voltage drop on any branch circuit shall not exceed 1.5 percent. The combined voltage drop of feeder and branch-circuit conductors shall not exceed 2.5 percent.

(1) Fixed Equipment. The voltage drop on branch circuits supplying equipment connected using wiring methods in Chapter 3 shall not exceed 1.5 percent. The combined voltage drop of feeder and branch-circuit conductors shall not exceed 2.5 percent.

(2) Cord-Connected Equipment. The voltage drop on branch circuits supplying receptacles shall not exceed 1 percent. For the purposes of making this calculation, the load connected to the receptacle outlet shall be considered to be 50 percent of the branch-circuit rating. The combined voltage drop of feeder and branch-circuit conductors shall not exceed 2.0 percent.

FPN: The purpose of this provision is to limit voltage drop to 1.5 percent where portable cords may be used as a means of connecting equipment.

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647.6 Grounding.

(A) General. The transformer secondary center tap of the 60/120-volt 3-wire system shall be grounded as provided in 250.30.

(B) Grounding Conductors Required. Permanently wired utilization equipment and receptacles shall be grounded by means of an equipment grounding conductor run with the circuit conductors to an equipment grounding bus prominently marked "Technical Equipment Ground" in the originating branch-circuit panelboard. The grounding bus shall be connected to the grounded conductor on the line side of the separately derived system’s disconnecting means. The grounding conductor shall not be smaller than that specified in Table 250.122 and run with the feeder conductors. The technical equipment grounding bus need not be bonded to the panelboard enclosure. Other grounding methods authorized elsewhere in this Code shall be permitted where the impedance of the grounding return path does not exceed the impedance of equipment grounding conductors sized and installed in accordance with this article.

FPN No. 1: See 250.122 for equipment grounding conductor sizing requirements where circuit conductors are adjusted in size to compensate for voltage drop.

FPN No. 2: These requirements limit the impedance of the ground fault path where only 60 volts apply to a fault condition instead of the usual 120 volts.

647.7 Receptacles .

(A) General. Where receptacles are used as a means of connecting equipment, the following conditions shall be met:

(1) All 15and 20-ampere receptacles shall be GFCI protected.

(2) All receptacle outlet strips, adapters, receptacle covers, and faceplates shall be marked with the following words or equivalent:

WARNING - TECHNICAL POWER
Do not connect to lighting equipment.
For electronic equipment use only.
60/120 V. 1-phase AC
GFCI protected.

The warning sign(s) or label(s) shall comply with 110.21(B).

(3) A 125-volt, single-phase, 15or 20-ampere-rated receptacle having one of its current-carrying poles connected to a grounded circuit conductor shall be located within 1.8 m (6 ft) of all permanently installed 15or 20-ampere-rated 60/120-volt technical power-system receptacles.

(4) All 125-volt receptacles used for 60/120-volt technical power shall have a unique configuration and be identified for use with this class of system. All 125-volt, single-phase, 15 or 20-ampere-rated receptacle outlets and attachment plugs that are identified for use with grounded circuit conductors shall be permitted in machine rooms, control rooms, equipment rooms, equipment racks, and other similar locations that are restricted to use by qualified personnel.

(B) Isolated Ground Receptacles. Isolated ground receptacles shall be permitted as described in 250.146(D); however, the branch-circuit equipment grounding conductor shall be terminated as required in 647.6(B).647.8 Lighting Equipment. Lighting equipment installed under this article for the purpose of reducing electrical noise originating from lighting equipment shall meet the conditions of 647.8(A) through (C).

http://www.freenec.com/T522.html

Guys - I have the Equi-tech cabinet mount power center with an earth ground- I am about to install the Furutech NCF outlets and someone mentioned to me that I should NOT hook up the ground wires to the Furutech outlet- Just cut it off before the outlet box-box- Does this make sense or not - thks

You do realize with a 60/120V grounded power system the receptacle is fed by 2 Hot ungrounded conductors? From either hot contact of the receptacle to a grounded object there is a 60 volt potential. More than enough to electrocute a person.

The audio equipment you plug into the receptacle was not designed to be connected to a 60/120V grounded power system. It was designed to be fed from a grounded power system having one current carrying conductor at ground potential, (the grounded neutral conductor), and the other current carrying conductor that is 120V nominal above ground, (the Hot ungrounded conductor.)

So what does that mean exactly?

There is only one AC mains protective overcurrent/ground fault circuit protection fuse that is in series with the Hot incoming mains ungrounded conductor.

In the event of a line to line overload condition the fuse will blow open. That still works the same with a 60/120V grounded system.

But what happens in the event of a ground fault condition? Remember with a 60/120V grounded system the two 120V mains are both Hot, 60 volts above ground.

If the Hot line that has the protection fuse, in series with it, were to have ground fault to the metal chassis on the load side of the fuse will it will blow? Well that depends if the chassis of the audio equipment is connected to the safety equipment ground that is bonded to the center tap of the 60/120V grounded power system. (By the way the center tap of the secondary winding is still called the neutral even though it is not used for power applications.) Your post is about defeating, lifting, the equipment ground from the equipment ground terminal on the duplex receptacle.

If the safety equipment ground is defeated, lifted, the chassis of the audio equipment will become Hot. There will exist a difference of potential, voltage, of 60V from the Hot chassis to any grounded object in the immediate vicinity of the Hot piece of audio equipment.

So what happens if you were to touch the Hot piece of audio equipment and a grounded object at the same time? There is a difference of potential of 60V present across the two points of your body in contact with the Hot chassis and the grounded object. Current will travel through your body. Thank goodness you have the GFCI protection. When the current reaches between 5ma to 6ma the GFCI circuit interrupter will trip open breaking both Hot 120V lines feeding the ground faulted audio equipment. (Well that’s if the GFCI works. That’s why they should be tested regularly by pushing the test button on the device/breaker.)

IF you didn’t defeat, lift, the safety equipment ground conductor from the duplex receptacle, then the protection fuse will blow in the even of a ground fault condition. Works just like the regular 120V power system of your home, right? It also should be mentioned the GFCI protection may have tripped open as well. It should, because the other Hot line feeding the other lead, leg, of the primary winding of the power transformer that is not fused. A ground fault circuit still exists from the hot line through the primary winding of the equipment’s power transformer to the ground fault connection of the equipment grounded chassis.

If the GFCI did not trip open, breaking both sides of the 120V hot lines feeding the ground faulted piece of equipment, that means the other Hot line is still live that is connected to the other side of the primary winding of the equipment’s power transformer. Is that a problem? Yes. The primary winding is now being fed by 60V. ( AC power in >> through the primary winding of the power transformer >> to the ground fault connected connection of the chassis >> to the equipment ground wire of the power cord >> to the safety equipment ground contact/terminal of the receptacle >> to the equipment grounding conductor of the branch circuit to where it is connected to the center tapped grounded neutral conductor. A completed circuit.) The primary of the transformer is being fed by 60Vac.

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IF you defeated, lifted, the safety equipment grounding conductor from the ground terminal of the duplex receptacle.

What IF a ground fault event, condition, were to happen on the other Hot AC (non fuse protected) mains line inside of the piece of audio equipment? Will the other Hot line protection fuse blow? It shouldn’t. It’s on the other side of the primary winding of the equipment’s power transformer. So will the chassis becomes Hot? Yes. And in the event you touch the piece of equipment while some other part of your body comes into contact with a grounded object, current will travel through your body. Hopefully when the current reaches between 5ma to 6ma the GFCI protection will trip open breaking the ground fault circuit path through your body.

If you did not defeat, lift, the safety equipment ground from the audio equipment then a ground fault event, condition, on the line will cause the 2 pole breaker in the electrical panel fed by the 60/120 grounded power system to trip open.

As you can see both the safety equipment grounding as well as the GFCI protection is critical for the electrical safety of a 60/120 grounded power system.

Probably the biggest reason a 60/120V grounded power system is only to be used in commercial or industrial controlled settings and under the control/supervision of qualified personnel.

(Note: The connection of audio equipment connected together by ICs was intentionally left out. That would add a whole other can of worms to the mix.)

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Curiosity killed the cat. What did you mean by,

I have the Equi-tech cabinet mount power center with an earth ground-

Earth Ground?

Guys - I have the Equi-tech cabinet mount power center with an earth ground

Does this make sense or not - thks