NFPA 70 Question

[PUMPDESIGNER]

My expertise is not in building electrical codes.

I read the following in NFPA-70:

NEC 230.95-A
SETTING – The ground-fault protection system shall operate to cause the service disconnect to open all ungrounded conductors of the faulted circuit.

I cannot see any way for this to be accomplished except by circuit breakers. I understand and agree with the concern for partially energized loads with faults, and circuit breakers are fine by me.
However does this code really require circuit breakers?
Is there a device allowing use of fuses?

Thank you.

PUMPDESIGNER

 

[ICman]

I'm no expert either, but isn't a ground-fault interrupter basically a breaker? Standard breakers and fuses both rely on temperature to act. Not much difference, except you have to replace the fuse. GFIs sense current to ground. When the current exceeds the threshold, it opens the Hot and Neutral lines (single-phase circuit).

 

[busbar]

Examples of low-voltage bolted-pressure contact switches are Boltswitch,

http://www.boltswitch.com

and Pringle,

http://www.pringle-elec.com.

Range for shunt-trip switches 800-6000 amperes.

 

[dwayned]

dwayned

The Ground Fault Circuit Interrupter or GFI monitors the current in the line and neutral conductors of a circuit and if there is an inbalance of more than about 7 mA the circuit is opened. This inbalance is caused by current returning to the source through the ground circuit rather than the neutral, the path could be a person in contact with the hot or line side of a circuit. The trip level is much lower that what the circuit is fused for, a typical 15 or 20 amp circuit that is operating on a time delay fuse or circuit breaker can carry a 200% overload for two minutes. Fuses or circuit breakers are designed for fire protection not to guard against electrical shock. Currents as low as 50 mA between the extremities can cause the heart to go into fibrillation. GFI's are required for damp or wet locations. Many small appliances such as hair driers have GFI's installed on the input cord. GFI's are also being incorporated in the design of many types of test equipment to protect the operator from a servere electrical shock. For more information on smart GFI circuits visit the Associated Research Web-site

http://www.asresearch.com.

article section.

Dwayne

dwayne

 

[resqcapt19]

Dwayne,
This is "ground fault protection for equipment" (GFP) and not for people (GFCI). The trip point can be set up to 1200 amperes for this application. 230.95 requires GFP protection on solidly grounded 150 to 600 volt wye systems with the service disconnect rated at 1000 amps or more. GFP is also required for feeders by 215.10. The GFP is intented to prevent arcing burndowns of switchgear, not to provide protection for people.
Don

 

[RonShap]

Relating to GFI protection and not GFCI. Other than GFI protection intergral to a breaker, there are stand alone GFI protection systems, like the GE GroundBreak system. The stand alone system will either shunt trip a breaker or disconnect switch.

There is three wire detection or four wire. Three wire is more prone to false trips if connected to large single phase loads.

 

[PUMPDESIGNER]

resqcapt19 - Sneaky bugger you are. I found my NEC Handbook, you are exactly correct. However I am still at a loss for how this is actually implemented in real practice.
It definitely says that the entire load must be disconnected, and fuses cannot accomplish this.

busbar - Those references you gave look suitable if they are ordered with the capacitor disconnect. However would not a circuit breaker work also?

PUMPDESIGNER

 

[busbar]

PD — Boltswitch and Pringle were suggested as non-circuit-breaker products to implement 230-95 ground-fault protection as a response to "Is there a device allowing use of fuses?" Apologies if I misunderstood your question.