2nd Step SSQ

What size grounds should be used on 1/0 ACSR circuit with a fault duty of 10,000A?

#2 for aluminum conductors 1/0 or smaller regardless of source voltage and fault current duty

What is the maximum fault duties for the three sizes of grounds used on distribution voltages?

#2=9,000A 2/0=18,000A 4/0=30,000A

What is the minimum size conductor used for single-phase transformer grounds?

#6 copper

What is the minimum size ground conductor for grounding applications involving wood poles?

#6 copper

What is the maximum acceptable level of error (percentage) when performing a TTR check on a transformer?

0.5%

What are the basic steps of pole top reduce?

1. Clear victim of imminent danger 2. Administer first aid 3. Lower the victim to the ground

What five precautions must be observed before and/or during Megger testing of a transformer?

1. Isolate the transformer 2. Watch out for shocks 3. Make a good electrical contractor with the terminals 4. Vent the transformer 5. Understand the transformer nameplate

What must an employee do upon entering an attended substation?

1. Report to the system operator 2. Enter required info in the visitor log 3. Provide system operator with suitable contact info

Explain how to phase the secondaries of two single-phase transformers?

1. make sure transformers are tapped up on same primary phases 2. check for proper voltage on both transformers 3. make sure neutral is connected 4. using voltmeter, check across phases, 0 means same phase, full voltage indicates opposite phases 5. check for zero volts and make connection, check before subsequent connections

What size conductors are typically used in single-phase lighting secondaries?

1/0 aluminum or #2 copper in all residential areas except those designated for min service 4/0 or 2/0 copper where the initial installation requires transformers larger than 25 kva

According to the APM, what size and type of rope is required for lowering a person from a pole?

1/2

What is the minimum clearance between the case, or hanger, of a 2.4 kV transformer and the secondary level?

10 inches

#4 AT amp

110

A clip-on ammeter reads 10A on a 120 V conductor. What is the resistance?

12 Ohms

What is the minimum height at which pole bands are to be installed?

12 feet

If a circuit has a total resistance of 20 ohms and a current of 6A, what is the voltage of the circuit?

120 V

#2 AT amp

145

What length pole stub would be used on a 60 foot pole?

15 feet

When dead-ending triplex to a crossarm, what is the minimum clearance between the bare neutral and the pole's centerline?

15 inches

What is the acceptable range for the angle in 1/0 ACSR on an angle pole with single arm construction?

15 to 30 degrees

#4 ACSR amp

160

What is the minimum depth for lateral ground conductors?

18 inches

When establishing the neutral grounds on a 4-wire system, what is the minimum clearance between the ground wire attachment point and the centerline of the pole?

18 inches

1/0 AQ amp

180

1/0 AT amp

190

Below what voltage may rubber gloves be used to contact energized wood pole bond wires?

20 kV

A 5000 W electric heating unit is supplied by a 240 V circuit. What is the current drawn by the heater?

20.8 A

What is the WLL of a stabilizer (silver) gin?

2000 lbs

4/0 AQ amp

275

1/0 ACSR amp

280

When dead-ending triplex in rack construction, what component is used to provide additional clearance from the pole?

3-spool extension rack

What is the maximum height at point of attachment for residential services?

30 feet

When constructing a 12/16 kV 2-single-phase transformer bank, what is the minimum distance between the primary line arm and the transformers' fuse holder arm?

30 inches

Secondary climbing space for arm construction

30 inches square

Secondary climbing space for triplex construction

30 inches square

4/0 AT amp

300

When stubbing a 60-foot pole, how many total bands are required for attaching the pole stub?

4 straps, two each, top and bottom

What is the requirement for placing HIGH VOLTAGE signs on wood poles with crossarm(s) supporting the lowest level of the line conductors energized in excess of 750v?

40 inches below the lowest level of line conductors energized in excess of 750v

4/0 ACSR amp

415

What is the full load (in amps) for a 100 kVA single-phase transformer with 120/240 V secondary service?

416.66 A

When separate bond wires are run on the same pole, what is the minimum clearance that must be maintained between them?

6 inches

336 ACSR amp

605

How much current would a 240 V heater, with 30 ohms resistance, draw?

8 A

653 ACSR amp

920

How is grounding achieved for a single-phase 120/240V secondary circuit?

All single phase circuits not exceeding 250V shall have the neutral point of the transformer grounded

What is the main benefit and drawback of a radial distribution system?

Benefit- cheapest and simplest Drawback- Least reliable

List two examples of transformer defects that may be detected with TTR and Megger checks.

Broken insulation or shifting components. Any connection inside the transformer can open up due to improper crimping or brazing or improperly secured fasteners.

When grounding multiple circuits on one structure, how are ground conductor sizes determined?

By the maximum size conductor and/or greatest fault-current duty on the structure.

What is the most important factor for making good low resistance connections with overhead conductors? Why is this factor important?

CLEANLINESS oxygen in air reacts rapidly to aluminum

What is the purpose of a distribution transformer?

Distribution transformers reduce primary voltages to secondary voltages to supply electrical service to customers.

List four different types of generating stations

Fossil fuel plants Nuclear plants Hydroelectric plants Wind turbines

Why are Megger checks performed on transformers?

Measures the effectiveness of a transformers electrical insulation.

What method should never be used to bend a pole to achieve the desired rake?

Never bend poles by pulling the guy

What are the minimum acceptable Megger test values for accepting both and new and old transformers, prior to installation?

New: >999 Old >500

What is special about Megger and TTR tests on 6.9 kV/9.5 kV (Ø-Ground) 240/120V, non-fused, single phase looped BURD transformers with three low-voltage bushings?

No megger test is possible since both windings and the tank are all connected.

What is the clearance requirements for a streetlight electrolier and secondary conductors?

No specified clearance is required for supply drops 0-750v if the streetlight pole is non-climbable and the cable is suitably insulated and mechanically protected

Is it permissible to operate a transformer's tap changer while it is energized or part of a bank?

No, a transformer, and it's bank, must be off line.

A connector on a ground assembly has broken, but it appears to be easily repaired. Is it permissible to make the repair and then use the ground assembly?

No. Ground assemblies shall not be modified, dissembled, repaired

When using a hand hoist, is it acceptable to use the chain and hook in a choker configuration? Why or why not?

No. The hook will break under stress

When constructing a 3-single-phase overhead transformer bank, how is the primary neutral ground connected?

Primary neutral ground is to be connected to the surge arrester and the tank discharge gap ground, but separate from the secondary neutral ground

How is the total resistance in a series circuit calculated?

RT=R1+R2+R3 etc.

How does a lineman find the fault duty for a particular circuit?

Refer to the Protection Engineering website

What is the purpose of a transformer tap changer? How does it work?

So the output of the transformer remains at the rates low voltage despite a higher or lower system voltage. This is accomplished by increasing or decreasing the effective number of turns in the high voltage winding.

What are the 3 basic nylon sling hitches?

Straight pull, Basket hitch, Choker hitch

List the approved grounding mediums, in order of priority.

Substation ground grid Multi-grounded primary neutral Steel structures Anchor rods If none of the foregoing is available, use approved temporary ground rod(s)

What are temporary ground rods? When would they be used?

Temporary ground rods are 5/8 inch copper clad steel material. Temporary ground rods may be used as an approved ground medium when priority ground mediums are not available

On a wood pole with two pole bands installed, where is the EPZ located?

The area on the pole between the two pole bands.

What precaution must be taken when stringing wire parallel to lines energized in excess of 35 kV?

The conductor being installed or removed shall be pulled over grounded rollers at the first structure adjacent to both the tensioning and pulling set.

What is fault duty?

The maximum rated current that a circuit may handle in a fault condition

Regarding determining ground conductor sizes, how is the "Redbook" utilized?

The redbook provides the highest fault duty listed for the line voltage being worked

Describe what a transformer's polarity is.

The relative instantaneous direction of current through the coils of a transformer.

Why are TTR checks performed on distribution transformers, prior to installation?

To identify defects that would show up as anomalies in the turns ratio of the transformer.

What is the purpose of a breakaway reel?

To recover overhead and underground conductors that are to be salvaged.

What is a USA, and when would it be required? What company provides SCE with USA service?

USA=Underground Service Alert, call two days before digging

Under what circumstance is it required that the substation ground grid be used as the grounding medium?

When grounding within 40 ft of ground grid and proper locations shall be selected for routing and attaching grounds to the ground grid

Concerning pole framing and cross arm construction on a rural pole, when are V-braces required?

When wire size is larger than #2 copper and 1/0 ACSR.

Is it permissible to reduce the required 6-foot clearance between secondary conductors and communications lines? If so, how?

Yes, with the installation of a guard arm

What precautions should be made when installing guy wires in coastal areas?

a corrosion resistant Bezinal guy wire is available

Typical, what component would be used to mount two 2.4 kV transformers on a pole? What is the weight limit for this component?

a two transformer mounting bracket 1600 lbs

What factors must be determined when selecting the proper sized guy wire?

conductor tension guy angle

Why are ACSR conductors factory-greased?

corrosion

Secondary climbing space for rack construction

diameter of pole + 5"(2 1/2" and 2 1/2" on each side) x 30" deep x 38" across the backside

What is a "B" bank substation?

distribution transformers and substations

How often should the neutral of a 12kV, 4-wire circuit be grounded?

every 1200 feet

How often is grounding equipment tested?

every 2 years

What are the two types of pole top extensions? Which is preferred?

fiberglass and wood fiberglass is preferred

What type of electrical hazard would lineman, working on a de-energized line that parallels an energized high voltage line, be exposed?

induction

What is the correct type of wire used in under the arm fiber?

insulated conductors

When dead-ending triplex in rack construction, what is the minimum installation clearance from communications and/or primary lines? May this minimum be reduced? If so, how?

minimum of 6 ft Yes. reduced to 4 ft with guard arm.

When are plastic "snapper" guy guards installed?

on all new and rebuild construction ( except high fire areas)

For what purpose is pole set-urethane foam used?

pole straightening pole setting in unstable or loose soils

List three situations where pole stubbing is not permitted.

poles in line of Grade 'A' construction poles carrying transformers angle poles, or poles carrying extra stresses

What two checks must always be performed prior to paralleling the secondary side of transformers?

proper voltage and phasing

Why is it important to install aluminum and ACSR conductors with the correct sag?

relaxation of pressure in connections, over time relaxation can cause overheating in connections

A 45- foot pole with one line arm at a Grade 'A' railroad crossing is found deteriorated. What option(s) are available to address this problem?

replace the pole

The APM prescribes two safety guidelines that must be performed prior to working on a transformer with banked secondaries. What are they?

secondary leads shall be disconnected in addition to pulling primary fuses

A 45- foot pole with one line arm, and no guys, is found deteriorated. What option(s) are available to address this problem?

steel stub, fiberglass wrap, or replace

Define step potential

the electrical difference between two points on the earth's surface, separated by distance of one pace

define touch potential

the electrical potential difference between a grounded metallic structure and a point on the earth's surface separated by a distance of a typical reach

What is the main reason why pole top extensions are installed?

to avoid pole replacement