Electrical PE Exam

Lighting Electrical PE Prep

2015-07-08T18:12:00.001-07:00

I passed the Electrical PE on the first try in. It's now been a few years and I have several engineers-in-training prepping for their PE tests. As I give them study resources I'll try and post the material here. Maybe I'll go back and update books that have new editions more applicable to this year's PE test.

The The Lighting Handbook: Reference and Application (Iesna Lighting Handbook) is now on its 10th Edition. They really should have made this thing two volumes as it is enormous. The IES Handbook itself says there is virtually no role for hand calculations in modern illuminating engineering, but they did have one on the PE so it's worth having the equations from Chapter 10 "Calculation of Light and Its Effects" handy. I know I never do hand calcs at work as there is far more sophisticated software, so having the book was good. I got the general knowledge question without the book. The hand calculation one was basically asking you to demonstrate knowledge of the lumen method by calculating the approximate foot-candles a certain light would provide to a space. I share an example below from a UK website that had a couple good examples.

Another source of practice questions comes from the National Council on Qualifications for the Lighting Professions Lighting Certified Professional exam. Their test prep handbook has 15 example questions that if you do lighting design at all professionally you should know the answers to off the top of your head or you should do enough reading from the IES handbook to learn the answers just to get a basic fluency in lighting. The NCQLP handbook can be found on their website.

Example Questions from 2015 NCQLP Candidate handbook

1. When evaluating daylighting systems in terms of glare, the
MOST important illumination conditions to be evaluated
are those occurring
A. when cooling loads due to solar gains are greatest.
B. when direct sunlight would penetrate the
fenestration.
C. at 2-hour intervals from sunrise to solar noon.
D. at the solstices and the equinoxes.

2. The ratio of mean lumens to rated lumens indicates
A. ballast factor.
B. voltage drop.
C. lamp lumen depreciation.
D. luminaire dirt depreciation.

3. The term luminaire refers to a
A. lighting unit exclusively for roadway illumination.
B. lighting unit exclusively for interior illumination.
C. complete lighting unit without lamps and ballasts.
D. complete lighting unit including lamps and ballasts.

4. Which of the following is the BEST definition of
illuminance?
A. time rate of flow of light energy
B. luminous flux incident on an object per unit area
C. flux density emitted from an object without regard for
direction
D. flux density emitted from an object in a given
direction

5. A hospital is experiencing RFI problems with its radiology
equipment. The lighting system in this area has been
identified as a 2 x 4 lensed troffer using F32T8 lamps and
an electronic ballast. Which of the following could be
attributed to the interference?
A. size of the luminaire
B. proximity of the luminaire
C. spectral output from the lamp
D. total harmonic distortion from the ballast

6. Two objects match in color appearance under a
fluorescent light source with a specific CRI and correlated
color temperature. Under which of the following light
sources would these objects MOST likely be expected to
match?
A. LED
B. halogen IR
C. reference lamp
D. ceramic metal halide

7. In barrier-free public buildings where emergency lighting
codes prevail, illuminated exit signs must provide an extra
warning for visually impaired visitors by
A. flashing.
B. incorporating braille letters.
C. using high-luminance lamps.
D. beeping loudly.

8. The lamp designations ES, SS, EW, and WM are for
fluorescent lamps that
A. are reduced wattage alternatives.
B. use energy-efficient ballasts.
C. require electronic ballasts.
D. have low acquisition costs.

9. Which of the following is a CIE/IESNA luminaire
distribution classification category?
A. semi-indirect
B. concentrating
C. forward throw
D. wall wash

10. A ray of incident light being reflected in one distinct
direction is representative of what type of reflection?
A. spread
B. diffuse
C. semi-specular
D. specular

11. In life-cycling costing, the measure of results is expressed
in
A. deffered expenses.
B. kWh saved.
C. net present value.
D. risk factors.

12. Group relamping of fluorescent luminaires is generally
recommended
A. upon change of occupancy.
B. at 60 to 70% of rated life.
C. at a 20% failure rate.
D. every 5 years.

13. Before construction is completed, an electrical contractor
should notify the lighting designer of the anticipated
completion date so that
A. the designer can walk through with the electrical
inspector.
B. ballasts can be calibrated by the electrical engineer.
C. a representative of the design office can help schedule
installation.
D. a schedule can be set for aiming and adjusting
fixtures.

14. Before a lighting system can be commissioned, the punch
list
A. must be completed and corrected.
B. must be certified by the inspector.
C. must be approved by the owner.
D. cannot be modified by the designer.

15. To ensure a lighting design’s projected energy savings are
realized after installation, a lighting practitioner must
A. adjust occupancy sensors and dimmers.
B. focus the adjustable accent lights.
C. finalize the punch list.
D. inspect the branch circuit wiring.

Example Calculating using the Lumen Method
The method is a commonly used technique of lighting design, which is valid, if the light fittings (luminaires) are to be mounted overhead in a regular pattern. The luminous flux output (lumens) of each lamp needs to be known as well as details of the luminaires and the room surfaces. Usually the illuminance is already specified e.g. office 500 lux, kitchen 300 lux, the designer chooses suitable luminaires and then wishes to know how many are required.

The number of lamps is given by the formula: where,

N = number of lamps required.
E = illuminance level required (lux)
A = area at working plane height (m2)
F = average luminous flux from each lamp (lm)
UF= utilisation factor, an allowance for the light distribution of the luminaire and the room surfaces
MF= maintenance factor, an allowance for reduced light output because of deterioration and dirt

Electric Shock and Electrical Burns

2011-02-24T16:06:00.000-08:00

The 12.5% of the test on Codes and Standards includes the NEC, National Electrical Safety Code (NESC) and Electric shocks and burns. I already went over the NEC so today it was on to shocks and burns.

Electrical shocks and burns is really the domain of NFPA 70e: Standard for Electrical Safety in the Workplace, and if you want to learn how to do Incident Energy and Flash Protection Boundary Calculations, Annex D of NFPA70E is a good resource, but if you don't feel like reading through all that and just want to familiarize yourself with the subject, Mike Holt has a short article on Electric Shock and a longer one on Electrical Burns.

I'm not really sure what kind of questions the NCEES will ask on Electric shock and burns. I could envision a question on calculating arc flash protection boundary distance question or a maximum safe shock duration.

Calculating Arc Flash Protection boundary distances is straight out of Annex D of NFPA 70e
To determine the maximum safe shock duration according to IEEE Std. 80, you can use the formula, T=0.116÷(E÷R), where T is duration in seconds, E is the electromotive force in volts, and R is resistance of the person, which is a constant 1,000 ohms.

Ugly's has a handbook for Electrical Safety and NFPA 70e which has some calculations in it that mirror Annex D. Google books has a preview of it which gives you a free 20 or so pages.

NEC digest also has a good article on PPE person protective equipment and burns

NEC Code Review

2011-02-23T15:29:00.000-08:00

Yesterday I attended an all day seminar on the 2011 NEC code which was a good review of how much of the code I don't normally use and need to freshen up on. The PPI book is only a brief survey of what topics the code covers and doesn't actually prepare you to answer code related questions so I went in search of something that would force me to go through a bunch of NEC problems. Tada, Mike Holt the NEC code guru comes to the rescue. He has free online quizzes for the 2002, 2005 and 2008 NEC. It randomly quizzes you on 10 NEC code questions and then gives you the section with the right answer if you mess up. It has 1900 different questions and it reloads different questions each time you open the quiz. If you want the full quiz all at once with all 1900 questions you can buy it for $25. Mike, you rock as always.

Mike Holt Free 2008 code quiz

Other free Mike Holt goodies:

Quick guide to conductor sizing
Electrical formula sheet
NEC 2008 Index - Saves time using the actual Index by cutting to the good stuff
Wiring & Raceway Chart

Measurement and Instrumentation

2011-02-17T13:33:00.000-08:00

The NCEES exam specification puts Measurement and Instrumentation at 7.5% of the Electrical Power PE test, but finding review materials on testing and measurements is tough. The measurement & instrumentation section includes:

1. Instrument transformers (pg 3-7)
2. Wattmeters
3. VOM metering
4. Insulation testing (pg 14-1)
5. Ground resistance testing (pg 14-5)

I couldn't find any good resources beyond the PPI book for VOM metering, but I found some good free Army Technical Manuals on the other subjects, which I have linked to above. You have to love free government info.

Lighting Design

2011-02-14T18:32:00.000-08:00

The Electrical Power PE test has 10% allocated for Special Applications including Illumination. I have a IESNA (Illuminating Engineering Society of North America) handbook and read through the Chapter 10: IESNA Lighting Design Geide and the PPI chapter on Illumination.

If you don't have access to these resources and want to have the basic Illumination topics covered I found 99% of this information available on the web. Once you know what terms to look up, most of them are on Wikipedia, but here are some additional sources that I found useful:

Lighting Basics & Terminology
Basic Lighting Calculations
Osram's Technical Basics of Light (Electromagnetic Spectrum, Blackbody Radiation, Planck Radiation Law)
Color Temperature (Wikipedia)
What is a Candela (Wise Geek)
Lumens, Illuminance, Footcandles
Basic Lighting Laws (International Dark Sky Association) Inverse Square Law, Lambert's Law, Cosine-Cubed Law
Luminance vs. Illuminance (Duke University)
Reflection vs. Refraction (Berkley)
Diffraction, Interference, Interference from Slits (University of Michigan physic's lab)

IESNA makes its 100 significant papers available for free online, which has tons of good information. Two of them in particular cover subjects from the manual fairly well:

A Lumen Method of Daylighting Design
A Versatile Method for Calculating Illumination and Brightness which goes over cavity ratios

Paranoid

2011-02-14T10:25:00.000-08:00

Want a way to make yourself paranoid about your study efforts? Read engineering forums where helpful people tell you what books they used and how they studied. After reading lists as long as my arm, all with different books and people touting minimum 400 hr study requirements I'm thoroughly paranoid about passing. Perhaps this will result in renewed motivation or paranoid buying of expensive reference materials that I'll never have time to get through?

Go here if you need to up your motivation/paranoia: Engineerboards.com

One useful thing that I gleaned after reading through a few threads is that there are way more NEC type questions on recent tests than the PPI book would lead you to believe, given their coverage of the subject. Yay for something I use everyday in my job being on the test.

Oh and the Grainger/Stevenson book is universally beloved. Thank goodness I found an old copy of that one. I got through 3 chapters out this weekend and found it to be well written. I still need to find a source of more practice problems though. One can only do so much reading.

Choosing a Calculator for Electrical PE

2011-02-11T15:33:00.000-08:00

In an attempt to count my time as preparing for the PE instead of procrastinating my reading assignment for the day, I decided it was time to get a new calculator.

NCEES calculator policy as of Spring 2011:

No other models of calculators will be allowed. Only the models listed below may be used on the examination.

Casio: All fx-115 models. Any Casio calculator must contain fx-115 in its model name. (Casio FX-115ES) ($19)
Hewlett Packard: The HP 33S ($53), HP 35s ($49) but no others.
Texas Instruments: All TI-30X ($12) and TI36X ($20) models. Any Texas Instruments calculator must contain either T1-30X or T1-36X in its model name.

It's important to practice with the calculator you will use on the actual test. I have been using the TI-30XIIS, which I have two of from someone else who took the PE. I quickly realized that the Civil PE and Electrical PE have one major difference when it comes to selecting a calculator. I need to easily be able to manipulate complex numbers and the TI wasn't cutting it. After a month of struggling with it and working around it, cursing at its lack of TI-89 skills, I gave up. This left me with the HP and Casio to choose from. The HP-33 is great if you need RPN, but it costs the most and didn't have great reviews, so I ended up buying two Casio FX-115ES from Walmart and calling it a day. I am so glad I switched. The three phase power problems are WAY easier. (beware, apparently this calculator is banned in some states its so awesome)

One thing that I really like about the 115ES is that you can input the values in rectangular and polar format in the same entry and it doesn't choke. Awesome! One less step for me, thank you.

Apparently you can get the HP-33 programmed to do all sorts of useful things for like $200, but I'd rather actually learn the material and the Casio does everything I need, thanks. I'll go back to using my TI-89 after this test.

Oh dear, I just spent 20 minutes monologuing about calculators. Back to power system analysis review.

Electrical PE Exam Reference Books

2011-02-09T13:40:00.000-08:00

Last night I took a break from studying to look up the recommended reference materials from the study book. They are all from like 1980s. You would think they could find modern equivelents, the books that we all use in school now, not seminal textbooks from the 80s that cost hundreds of bucks to track down!

I know I'm probably being picky, but honestly the list is useless. Bring the NEC, NESC, IESNA handbook and your books from school, but I don't think I would track down a single thing on this list. Any suggestions for other references, you know modern ones?

This was one of the rare ones that's been regularly updated since the 80s:

This one is from 1980:

An Introduction to Digital and Analog Integrated Circuits and Applications

Also from 1980:

Applied Electromagnetics

Oh I found one, and its $215...at least its modern

Back to 1981:

Electrical Power Technology (Electronic Technology Series)

At least you can pick this 1981 classic up for less than 2 bucks:

Linear Circuits

Woohoo, a modern update:

Back to the old stuff...

Earley and Sheehan haven't updated their National Electrical Code Handbook since the 2005 code cycle, might want to spec the new authors:

I thought this title was out of print, then I realized the PPI author spelled the author's name Marne wrong (Marie). At least the book is up to date.

Seriously, you want me to look at NEC code examples from 1999?

Ok, its from 1994, but someone else who recently passed the PE recommended it too:

The fact that this came out in 1999 and I think that's recent is reflective of the rest of this list.

2006! Woot, this list is going to end on a good note.

Yeah, I wouldn't take a much older book on Biomedical engineering seriously. Good call using a somewhat modern reference.

In fairness to the author, the new IESNA handbook only came out a month or so ago so I won't fault him for spec'ing the ten year old one.

A decent looking book, but unneeded for the Power test probably, might want to edit the list for each test now that you're selling 3 different prep books.