Remembered NETA 2 Questions Help

[BruceG400]

5.) A Multimeter is device that:

a.) is connected in series, low impedance
b.) is connected in series, high impedance
c.) is connected parallel, low impedance
d.) is connected parallel, high impedance
answer is d

I agree that the answer is D and would answer the question that way too, but not to forget that most DMMs are rated to be used at 10 amps in series with the circuit.
That would be more handy in an electronics circuit where accuracy would be a great concern, but it is an option, so the question is misleading since the DMM can technically be used in series and parallel.

[BruceG400]

6.) What is the highest pickup for a low voltage-480 system ground?

a.) 600 A
b.) 800 A
c.) 1000 A
d.) 1200 A

Ground Fault protection can never exceed 1200 amps.
Even if the breaker is 4000 amps or larger and the dial for GF setting would reach 1200 amps on the first few notches of settings, once the setting reaches 1200 amp, the settings above that point will not go any higher than 1200 amps.

[BruceG400]

7.) Why do an insulation test between neutral and ground?

I read this and was confused on the wording. Are you talking service entrance or non service entrance? The question did not specify! Come on NETA. Killin me smalls....


We typically perform GF test for new installations. We typically remove neutral and/or neutral to ground bond to test for downstream bonding. This test can be performed with an ohm meter, but recently, we have had city inspectors require an insulation test (AKA Megger test) be performed to check for downstream bonding.
I agree that it is overkill, but the inspector gets what the inspector wants.

[BruceG400]

8.) Interlock on MV MCC between switch and contactor. Why?


My experience has been with a slow-close disconnect that was interlocked with the door/cover and the contactor.
The disconnect only closed/opened as fast as you moved your hand.
My thought was that the contactor had to be opened before operating the disconnect, that way the disconnect is not operated under load.
In this case, the contactor mechanism malfunctioned and stuck in a position, which also damaged the main disconnect linkage due to repeated attempts to operate the disconnect.

[BruceG400]

9.) What is the role of a VFD?

Watch for this one. The wording in the answers was VERY confusing.


VFD Variable Frequency Drive (also known as Variable Speed Drive) controls the speed of a motor by varying the frequency of voltage that is delivered to motor. The VFD rectifies the AC to DC, then DC is inverted to AC, but when the DC is inverted to AC, the frequency can be varied by the speed of switching in by PWM (Pulse Width Modulation).
This rapid switching comes at a price. To create a varied frequency, this switching can distort the sinewave, and/or cause excess vibration in the motor. The motor needs to be rated for use with a VFD or the motor may be short lived.

A VFD can also be used as a form of soft-start, but the main reason is to control the speed of the motor since starting and stopping a motor is harder on the motor than running it at a reduced speed.

[BruceG400]

14.) What is the outdoor panel class?

a.) Class 2
b.) Class 3
c.) Class 3R
4.) Class 4


Outdoor panel rating would be NEMA 3R. R for raintight. This does not mean it is submersible, it only means that rain that runs down the panel, will not makes its way into the enclosure due to how the lips of cover overlap or divert rain away from panel.
Typically a dry-type transformer is a NEMA 2 but can but can be converted to a 3R with additional rain guards over vents.

[Kalbi_Rob]

7.) Why do an insulation test between neutral and ground?

I read this and was confused on the wording. Are you talking service entrance or non service entrance? The question did not specify! Come on NETA. Killin me smalls....


We typically perform GF test for new installations. We typically remove neutral and/or neutral to ground bond to test for downstream bonding. This test can be performed with an ohm meter, but recently, we have had city inspectors require an insulation test (AKA Megger test) be performed to check for downstream bonding.
I agree that it is overkill, but the inspector gets what the inspector wants.

I would disagree as NETA ATS 7.14.2 states: Measure the system neutral-to-ground insulation resistance with the neutral disconnect link temporarily removed. Replace the neutral disconnect link after testing.

Definition of insulation resistance test is performed with active voltage applied. Resistance of a system can be checked using an ohmmeter, but insulation can only be tested via potential. I would agree with the City Inspector. I've always tested with ohmmeter prior to applying voltage as most systems are <1 ohm, and require additional work.

[BruceG400]

I would disagree as NETA ATS 7.14.2 states: Measure the system neutral-to-ground insulation resistance with the neutral disconnect link temporarily removed. Replace the neutral disconnect link after testing.

Definition of insulation resistance test is performed with active voltage applied. Resistance of a system can be checked using an ohmmeter, but insulation can only be tested via potential. I would agree with the City Inspector. I've always tested with ohmmeter prior to applying voltage as most systems are <1 ohm, and require additional work.

Since you agree with the inspector, are you saying you normally take a resistance reading for downstream bonding with an insulation resistance tester?
I agree that downstream bonding needs to be tested while any neutral to ground reference on line-side needs to be removed. We have always used an ohm-meter in the past to run this test with bonding jumper removed, but have only recently been required to use an insulation resistance tester.

[JCarroll]

I agree that the answer is D and would answer the question that way too, but not to forget that most DMMs are rated to be used at 10 amps in series with the circuit.
That would be more handy in an electronics circuit where accuracy would be a great concern, but it is an option, so the question is misleading since the DMM can technically be used in series and parallel.

On the test I took about a month ago the question actually asked something along the lines of

"A DMM used to measure voltage is connected:" or
"A DMM used to measure current is connected:"

It was in no way ambiguous as to what answer they were looking for.

[Kalbi_Rob]

Since you agree with the inspector, are you saying you normally take a resistance reading for downstream bonding with an insulation resistance tester?
I agree that downstream bonding needs to be tested while any neutral to ground reference on line-side needs to be removed. We have always used an ohm-meter in the past to run this test with bonding jumper removed, but have only recently been required to use an insulation resistance tester.

I've always taken my Megger MIT/420 and used the ohmmeter to verify Neutral and ground are clear with the neutral disconnect link removed. On New Construction (which for whatever reason the East Coast Mid-Atlantic region doesn't require NEC 230.95 test), I will take and perform a insulation resistance test. I don't perform it on maintenance test because of potential of downstream devices. So, for an inspector on new construction, yes per every procedure I have seen it is written as perform an insulation resistance test.