Low Voltage Qualification
Explain the intent of the "Assured Equipment Grounding Conductor Program" (AEGCP).
A program that each department has in place to verify the ground path for portable equipment (welders, stand up grinders, pressure washers, etc.) that are not used with a GFCI. Each piece of equipment must be tested every quarter.
Explain how you would ensure the equipment in your area is tied to ground.
A simple visual inspection or a test using an ohm meter can verify your equipment is properly grounded.
What type of PPE do you have? What is its purpose?
All E&I techs should have a min. of category 2 flash hazard PPE as well as insulated gloves (most have class 0)
Explain how you would properly dispose of used ballasts in your area.
Ballasts 1979 or older are considered hazardous waste and must be disposed of in a hazardous waste container.
What must you do to keep unqualified people from entering the limited or flash protection boundary (whichever is greater) while work on an electrical panel is being performed?
Barricade the area rope off / watch out person.
Why is the incident energy higher at the secondary of unit substations?
Because most of our transformers are step down transformers which provide a lot of available current in addition to the impedance of the transformer itself, causes trip times to be high.
What must happen for an individual to cross the Limited Approach Boundary?
Must be qualified or be under the direct supervision of a qualified person. The E&I techs that open the panel/enclosure must maintain this distance (ensure unqualified folks do not enter).
What must happen for an individual to cross the Restricted Approach Boundary?
Must have Shock Protection.
What must happen for an individual to cross the Flash Hazard Boundary?
Must have flash protection on and be L.V. qualified.
Does a 20 amp circuit breaker protect electrical workers from shock? Why or why not?
No. It only protects equipment. Only 100 to 200 mA are needed to stop a person's heart.
What is meant by the term "Overdutied"?
Overdutied means the equipment's S.C. current rating is less than the available S.C. current.
What are 2 conditions that cause a fuse to blow?
Overload Short
What is meant by the term "Overloaded" (current) as it pertains to circuits or feeders?
Overloaded means the circuit has more current flowing compared to its rating or ampacity.
Explain the intent of PCP-650.
P&G's document for all P&G sites to follow relative to electrical safety.
At what current range does "painful shock" occur?
Painful Shock - 8 to 15 ma
Explain the purpose of the equipment grounding conductor.
Provides a path back to the source to operate the protective device (breaker, fuse, etc.). Maintains exposed metal at ground potential (protects people).
Explain how to test a GFCI device.
Push the test button plug in the tool Try tool (should not operate) Press the reset button Now the tool should operate
What should you do if your insulated gloves are damaged?
Remove from service, do not use. Destroy them so others don't accidentally use them.
Explain the proper procedure for grounding out a unit substation.
Remove load, open ACB's, open LBF, ground line side of fuse, ground load side of fuse, ground secondary bus.
What are a few examples of "category dangerous" locations?
Secondary side LV (480) substations due to the increased amount of current as well as the impedance of the transformer (this will increase the amount of time the upstream protective device operates).
What medium voltage equipment do you have in your area?
Secondary side of the substation transformers (switch gear) Secondary side of a transformer
Explain how a megger works.
Sends a high voltage (low current) signal through and measures leakage current back to the meter. This tests the insulation capabilities.
Where does the completed EWP go ounce the work is complete?
Sent to site power - The permit is reviewed every year & document saved on file for at least 3 years.
What are the 3 hazards of electricity?
Shock - Current flowing through your body Arc Flash - Release of electrical energy through the air producing extreme HEAT and light Arc Blast - Rapid expansion of gasses, circuit parts, molten metal, etc. creating an over pressure situation similar to an explosion.
Where are the prints for your area located?
Single line & EDS.
What does "service factor" mean on a motor?
The "service factor" rating of an electric motor is a multiplier that indicates how far beyond its official nameplate power rating a motor can be be driven before overheating. An electric motor with a nameplate rating of 10 hp & a service factor rating of 1.15 can handle a load of 11.5 hp for a short period of time.
What boundary is often referred to as the "Just Curable Burn" distance? Why? What is the cal/cm2 rating?
The Flash Protection Boundary is referred to as the "just curable burn" distance. This at 1.2 cal/cm2 incident energy because this is the energy you can withstand without permanent damage.
What is "Incident Energy"?
The amount of heat impressed on a surface (person) that is generated during an arcing event/fault. Measured in cal/cm2
What does the code date on your insulated gloves mean?
When they were last tested or some show when they need to be tested again.
When do you need Flash Protection?
When within the Flash Protection Boundary or when interacting with the equipment in a way that could cause an electrical arc (voltage testing, trouble shooting, commissioning new equipment, operating an ACB, MV disconnects, after maintenance, - anything that is not normal operating conditions).
Is pulling wires through conduit with other energized circuits considered "energized work"? If yes, why?
Yes. The risk is damaging the insulation on the existing circuits, creating a shock hazard. Also, induced voltage from energized circuits creates a shock hazard. All the circuits in the conduit must be de-energized before pulling wire.
What is meant by S.C. (Short Current) current? What is the intent of a S.C. study or evaluation?
A S.C. study or evaluation is intended to check the available short circuit current & compare it to the rating of the panel.
How would you determine if a motor is running in its allowable range? (No answer)
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What is a good reading of a 3-phase motor? How does moisture effect these readings? (No answer)
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What type of meter do you have? what do you use it for? (No answer)
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What is the "Restricted Approach Boundary" for low voltage equipment?
1' from exposed and potentially energized conductors.
According to the NEC, what is the smallest size wire you can use on a 20 amp circuit?
12 awg
According to the NEC, what is the smallest size wire you can use on a 15 amp circuit?
14 awg
An electrical arcing event or arc flash can generate a huge amount of heat. What temperatures are often reached?
30,000 C or 3 times hotter than the sun.
What is the "Limited Approach Boundary" for low voltage equipment?
4' from fixed exposed and potentially energized conductors. 10' from movable exposed and potentially energized conductors.
What is the "Flash Protection Boundary" for low voltage equipment?
4' or follow the Flash Hazard Label on the equipment.
What are the different levels of Electrical Qualifications and the voltage level associated with each one?
"General Awareness" - for all employees (BEST training) "Task Qualification" - for a specific task. "Low Voltage" (LV) - 50 to 1,000 v "Medium Voltage (MV) - 1,000 to 36,000 v "High Voltage (HV) - 36,000 volts & up
What determines the speed of an AC motor?
#of poles x frequency / 120
Explain the different voltage sources & levels you would expect to see in a motor starter bucket.
*3-phase, 480 volts *120 control voltage *Sometimes 24 volts
Explain the values you would see on a fuse (markings, size, etc.). There are 3 of them. What do they mean?
*Amps - The amount of current the fuse will allow to flow, ounce amps is > this rating, the fuse will open. *Voltage - The highest voltage level you can use with the fuse *IR - (Interrupting Rating) The highest amount of short circuit current the fuse can withstand.
What are typical wire colors inside a motor starter bucket?
*Black - 480 v *Green - Ground *Green & yellow - Ground *Red - 120 v *White - Neutral *Blue - 24+ DC *Grey - 24- DC *Orange - foreign Sometimes brown, orange, yellow is 480 v
What are some requirements for executing "energized work"?
*CPR certified person (not include as one of the qualified) *2 LVQ people *AED on site *Job plan & JSA filled out *Signatures and approvals required *Energized work permit
What are the factors that determine the severity of a shock?
*Duration - time current flows through body *Path - path current travels through body *Voltage - magnitude of voltage *Resistance - how good is the connection, sweat is a factor, how well you are grounded, etc.
What is the process for disposing of fluorescent light bulbs?
*Hard hat, face shield, leather gloves *Dispose in approved satellite storage area.
What should you do if someone got shock?
*Isolate the energy source (disconnect, breaker, etc.) *Ensure no one else is at risk. *Contact the main guard shack, call for help, pull fire alarm *Follow the green card / crowd control *Bring to health services and/or Tyler - will need EKG and based on outcome may need a blood test. *Must use an ambulance to transport to Tyler
What type of information would you expect to see on a motor nameplate?
*Manufacture's name *FLA *RPM's *Frequency *# of phases *Locked rotor indicating letters (NEC 430.7(B)) *Frame size
What determines how badly you get burned in an Arc Flash event?
*The incident energy at this location in the power system *Distance you are from the arcing event *Amount & type PPE you are wearing (category) *SC current *Duration of arc event
Explain every step you would take to verify a circuit is de-energized that feeds a 3 phase motor.
*Turn off the equipment (load) *ID flash protection and wear *Turn off / open disconnect device *LOTO *Wear shock protection *Check your meter on a known live source *Check your circuit - phase to phase and phase to ground *Check your meter again
Explain how a ground fault finder works. (No answer)
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What flash protection is required for equipment above MCC/PDP level when interacting (opening / closing a disconnect) with doors & covers closed? ------------------------------- (No answer, yet.)
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What is Category 0 PPE? ----- (No answer, yet) -----
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Do you have insulated tools? What is the rating on them? (No answer)
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Explain how you would determine if you have a ground fault on equipment in your area. (No answer)
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Explain how you would determine that substation equipment you are about to work on is properly de-energized, isolated, locked out and grounded. (No answer)
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Explain the risks involved with installing a hardware or software jumper in a process or bypassing a safety device (guard door, latch, etc.) What must be done?
Before altering any safety device, must follow PSP 494 "Altering a Safety Device". This is a process that walks you through the risks involved and how to mitigate risks. Requires counter measures to be put in place to ensure a safe working environment. Must understand the process in detail and how a "jumper" or "bypass" can change its functionality.
Explain the safety hazards associated with current transformers (CT's).
CT's can produce extremely high voltages when the CT's circuit is opened with current flowing.
Explain how you would inspect your insulated gloves.
Check for cracks, cuts, contamination; fill with air to ensure they can hold pressure.
What are common failure modes for insulated gloves?
Cracks between the fingers and where ever the glove flexes a lot.
Explain how you would de-energize, lock out, test, and ground out a unit substation.
Create a job plan (job plan) Shed load / turn off loads Open ACB's (lock out) Open LBF (main) Lock out Test Ground out primary side Ground out secondary side
If you can not use a GFCI with a portable piece of equipment (3-phase welder), what must be done before it can be used?
Must be part of the AEGCP (Assured Equipment Grounding Conductor Program) Check continuity of ground prong to the equipment case / enclosure. Megger a phase to ground to ensure insulated.
What would you do if someone told you that they received a "static shock"?
Determine the exact area the shock was received, determine if it is possible that the "static" shock could have been a "real" shock (current flow through the body), if yes - take them to health services for evaluation. If there is no possible way they received a real shock - no medical treatment is required and evaluate the work area to see if the static can be eliminated.
What was the last shock incident that occurred in your area or at this site? What caused it?
Dock door switch, not properly grounded - wrong enclosure.
Explain the intent of the NFPA-70E.
Document for protecting electrical workers. Arc / flash and shock protection. Focus on safeguards of electrical *conductors & equipment within building / structure *conductors connecting installations to a supply of electricity. ex: shock /arc boundaries, LOTO, PPE
When do you need or require a 2nd qualified person?
Energized work, remote locations, or whenever the individual feels they may need a 2nd person (unfamiliar area or equipment)
What PPE is required when checking fuses in an MCC bucket? How do you determine this?
Flash & Shock protection to verify power, If the MCC has a Flash Hazard Label then follow the category PPE on the label, if it does not then you must follow the "Table Method" in PCP-650 or NFPA-70E.
Explain why it is important to investigate and resolve ground faults in a timely manner.
Ground faults will over time degrade insulation of conductors because cable insulation is rated for cable to cable value (2 x insulation thickness). During a ground fault, ground is at phase potential and now only 1 x insulation thickness exists between phases. Also, if you have a second ground fault, it would be a phase to phase fault (high fault current).
What is the correct position to be standing in when opening or closing a disconnect?
Hinged side, off to the side, not directly in front of it.
Explain how you would test a fuse.
If installed and energized, can test using voltage setting on your meter (using proper PPE), test across the fuse. Also, if de-energized and removed from the circuit, can be tested using the ohms setting on your meter. This is the preferred method. Should be 0 ohms or close to 0 across the fuse.
Explain the hazards associated with a shared neutral.
If you create an "open neutral" you will have source voltage on the neutral leg. De-energize the circuit before creating an "open neutral".
Where are the single lines for your area located?
In our shop.
How often should you inspect your gloves? How often do they have to be tested?
Inspect before every use & tested every 6 months.
Explain the intent of the NEC.
Installation standards. Adopted as law in PA. The practical safeguarding of persons & property from hazards arising from the use of electricity.
Explain the operation of a GFCI device,
It monitors the current on the hot and neutral and will open / trip if it senses a 5 ma difference in 1/40th of a second.
explain the different types of motor starters in your business area.
Large NEMA style (rebuild-able) IEC - small throw away
What is the proper storage method for your insulated gloves?
Leather and rubber insulated gloves should be stored separately and with the cuffs down. This will prevent tools or other objects from falling into the gloves causing possible damage.
What is "energized work? Examples...
Lifting wires > 50 volts while energized, racking in / out ACB or MCC bucket, tightening terminals while energized, etc.
Explain the term "conductor".
Materials that are made up of elements that have 1 to 3 valence electrons which allow current to flow easily. (copper, metal, etc.)
Explain the term "insulator".
Materials that are made up of elements that have 6 to 8 valence electrons which prevent current flow. (The valence electrons are very difficult to free). (rubber, glass, ceramic, etc.)
What type of insulated gloves do you have? What is their voltage rating?
Most E&I techs have class 0 gloves rated up to 1,000 v
What is the purpose of the Equipment Grounding Conductor? How does it accomplish its purpose?
The equipment ground provides a current path back to the protective device, fuse, or breaker, in the event of an insulation failure in the equipment. This ensures the operation of the protective device & isolation of the fault. It also maintains the exposed metal of the equipment at ground potential to prevent electrical shock to the person touching that metal.
How do you describe "voltage" or "electromotive force" (EMF)?
The force or pressure that causes electrons (current) to flow. As the potential difference between 2 points increases, the more pressure exists to push current to flow.
What is meant by "Category Dangerous"?
The incident energy is greater than 40 cal/cm2 & there is no recognized PPE that would protect you.
How would you describe "current"?
The movement of electrons from one atom to another. (Measured in amps)
When sizing a fuse, what is the general rule-of-thumb for "time delay" and "non-time delay" for an induction motor?
Time delay - 175% of FLA Non-time delay - 300% of FLA
Explain the intent of the power & instrumentation portion of the IRRT checklist / process.
To ensure new or modified equipment meets codes and can be operated and maintained safely. All new equipment must meet NEC, PCP-650, and site safe practices.
Why do we have a L.V. qualification process?
To ensure that all employees are trained and qualified to do this type of work safely.
Explain the intent of the "Site Power Master Plan". What is the intent? Why do we have one?
To provide direction for loading of the incoming lines, manage future expansion of the power system infrastructure, manage replacement of power system components, transformer loading, help drive our electrical safety culture across the site by providing direction on electrical safety, safe practices, codes, etc.
Explain how you would test current flow in a system.
Using a clamp-on amp meter, or for low current applications, can use a meter (Fluke 87) in line with the circuit.
At what current range does "Ventricular Fibrillation" occur?
Ventricular Fibrillation - 100 to 200 ma Your heart is not beating normally. The heart is twitching and not effectively pumping blood.