Master Electrician Reference

Master Electrician Reference (or MER for short) is your electronic pocket electrician reference guide. It is an app, a book, and a calculator all in one!

Pick the version of MER that matches the NEC® code cycle you are using.

NEC Adoption by States as of April 2020

2017 Full Version
2014 Full Version
2011 Full Version
2011 Lite Version
Get it on Google PlayFull Version

We do not charge a yearly subscription fee nor do we have in-app purchases.

Have ideas for improving MER? Send us an email ( with your suggestions!


An Electrical Reference Guide

Master Electrician App for iOS
Master Electrician Reference

MER is for everyone who works with electricity

If you are an electrical designer, engineer, installer, contractor, facility manager, inspector, exam candidate, apprentice, electrician, journeyman, architect, or technician, MER is for you. If you do residential, industrial, and commercial work, MER is for you. Simply, if you work with electricity, this reference guide is for you!

MER is developed in collaboration with a Master Journeyman Electrician IBEW

MER supports the NFPA 70-2011, 2014, 2017 NEC® Codes

MER contains tables reprinted with permission from NFPA 70-2011, 2014, 2017, National Electrical Code®, Copyright © 2010, 2013, 2016, National Fire Protection Association, Quincy, MA 02169. This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety.

MER is used throughout the United States


Why You Should Use Master Electrician Reference

MER has explanations

MER has tables

MER has formulas

MER has pictures and diagrams

MER has calculators

MER is easy to use

MER is always there when you need it


Master Electrician Reference Features

Simple Circuits
– Ohm’s law, series and parallel circuits, capacitance, inductance, impedance, and reactance.

Distributed Systems
– Distribution wiring diagrams for 120, 208, 277, and 480 volts, color codes, breaker sizes, light switches and bells diagrams.

Electrical Formulas
– Formulas for kVA, kW, and HP.

Color Codes
– Color codes for capacitors and resistors.

Motors and Wiring
– Standard motor and motor starter sizes, tables of full-load currents, locked-rotor information, overload units, OCPD, nameplate information, synchronous motor speeds, three-phase STAR and DELTA diagrams, three-wire start-stop diagram, motor frame dimensions, and motor enclosure types.

– KVA ratings for single- and three-phase current, transformer formulas.

Conductor Properties
– Conductor tables, AWG and metric wire sizes, twist-on pressure connectors, and wire combinations.

– Ampacities in raceway, cable, earth, and free air, and derating tables.

Conduit Fill table

Grounding Sizes
– Equipment grounding conductor (EGC) and grounding electrode conductor (GEC).

Metal Boxes
– Images and sizes of metal boxes, junction / device boxes, junction / pull boxes.

Voltage Drop calculations

Dictionary of electrician terms

Insulation Charts
– Table of cable and wire types

Electrical Symbols

– Plugs and wiring diagrams, enclosure types, standard underground boxes, standard fuse and breaker sizes, standard pull box / junction sizes, standard gutter and wire-ways, standard switchboards, standard busway, standard busbar ampacity, standard panelboard sizes, and standard disconnect sizes.

Math and Conversions
– Formulas for geometry, fractions, temperature conversion, trig tables, unit conversions, metric prefixes, and conversions between inches and millimeters.

Conduit Bending
– Includes the guide “The Master Bender Way” on how to bend conduit.

Conduit Weights

Copper Wire Cost

Hole Saw Sizes

Material Raceway Support

– Fluorescent, high-intensity discharge, incandescent, LED, and low-pressure sodium.

Standard Tool List

– Lugs, bolts, and screws, tightening torque.

Dry, Damp, and Wet Locations

Hazardous Locations

Wiring Methods

– Lock-out / tag-out (LOTO), and a safety manual and first aid.