NACE CP2 PRACTICE EXAM QUESTIONS AND
DETAILED SOLUTIONS 2026
▶ measurement methods. Answer: true voltage reading
voltmeter reading
% error calculations
effect of voltmeter resistance
IR correction methods
▶ test stations. Answer: allow electrical connection to structure for
potential measurements and bonds.
Spans allow current and direction (IR drop).
inistall during construction
▶ pH. Answer: measure of acidity(hydrogen ion concentration)
high pH is alkaline
low pH is acid
pH is a log function therefore each increase in pH is a factor of 10.
▶ RECTIFIER. Answer: - positive to anode
-negative to structure
- AC suppy
-AC circuit breaker
-Transformer (increase or decrease voltage)
-AC fuse
-rectifier bridge - diodes change AC to DC
-Voltmeter and Ammeter
-Surge Protection
-Filters
Esecondary = (Eprimary x Secondary turns) / primary turns
▶ Reference electrode location. Answer: the reference electrode should
be placed as close to the structure as practical. (underground piping or
tanks- over the center of the structure, multiple readings along the structure
as required)
,internal surfaces of storage tanks, waterfront and offshore structures (as
close to the wall as possible)
▶ impressed current vs sacrificial. Answer: impressed current- higher
current, better control
sacrificial- no power required, less maintenance, easy to install, less land
▶ AC considerations. Answer: capacitance, inductance, and resistance
hazardous AC potential - 15 Vac
Safe method of connecting ground0 cable to ground then to pipe
arcing hazards
corrosion rates from AC (current density)
switching or pulse rectifiers
▶ Reference cells. Answer: CuCuSO4- most common, (soil, fresh water)
AgAgCL - seawater
Calomel- lab
Hydrogen - standard (lab)
zinc- stationary
▶ Cathodic Protection. Answer: protect the cathode
attempts to bring the cathode potential as negative as the anode potential
NACE criteria- what are the exceptions?
-high temperature
-bacteria
-sulfides
-acid environments
-dissimilar metals
, ▶ Isolation Requirement. Answer: confine protection to protected structure
thus limiting the current required for protection.
use for stray current with care
▶ continuity requirement. Answer: bonds are necessary for continuity:
mechanical fittings (compression, bell & spigot, rebar etc.)
▶ Impressed Current Anodes. Answer: graphite
cast iron (high silicon chromium)
mixed metal oxides
scrap iron
conductive polymer
cylindrical, tubular
soil..... backfilled in coke breeze
▶ current span. Answer: current in a pipe can be measured by taking a
voltage drop across a known length and either calibrating the section in
question or using resistance from tables.
unknown pipe size must be calibrated by using I/ deltamV or R= V/I using 4
wires
▶ Sacrificial anode types. Answer: magnesium
zinc
cylindrical, bullet, ribbon, bracelet
soil backfilled in gypsum, bentonite mixture to reduce contact resistance to
soil and to retain moisture
make sure to remove plastic shipping bag
DETAILED SOLUTIONS 2026
▶ measurement methods. Answer: true voltage reading
voltmeter reading
% error calculations
effect of voltmeter resistance
IR correction methods
▶ test stations. Answer: allow electrical connection to structure for
potential measurements and bonds.
Spans allow current and direction (IR drop).
inistall during construction
▶ pH. Answer: measure of acidity(hydrogen ion concentration)
high pH is alkaline
low pH is acid
pH is a log function therefore each increase in pH is a factor of 10.
▶ RECTIFIER. Answer: - positive to anode
-negative to structure
- AC suppy
-AC circuit breaker
-Transformer (increase or decrease voltage)
-AC fuse
-rectifier bridge - diodes change AC to DC
-Voltmeter and Ammeter
-Surge Protection
-Filters
Esecondary = (Eprimary x Secondary turns) / primary turns
▶ Reference electrode location. Answer: the reference electrode should
be placed as close to the structure as practical. (underground piping or
tanks- over the center of the structure, multiple readings along the structure
as required)
,internal surfaces of storage tanks, waterfront and offshore structures (as
close to the wall as possible)
▶ impressed current vs sacrificial. Answer: impressed current- higher
current, better control
sacrificial- no power required, less maintenance, easy to install, less land
▶ AC considerations. Answer: capacitance, inductance, and resistance
hazardous AC potential - 15 Vac
Safe method of connecting ground0 cable to ground then to pipe
arcing hazards
corrosion rates from AC (current density)
switching or pulse rectifiers
▶ Reference cells. Answer: CuCuSO4- most common, (soil, fresh water)
AgAgCL - seawater
Calomel- lab
Hydrogen - standard (lab)
zinc- stationary
▶ Cathodic Protection. Answer: protect the cathode
attempts to bring the cathode potential as negative as the anode potential
NACE criteria- what are the exceptions?
-high temperature
-bacteria
-sulfides
-acid environments
-dissimilar metals
, ▶ Isolation Requirement. Answer: confine protection to protected structure
thus limiting the current required for protection.
use for stray current with care
▶ continuity requirement. Answer: bonds are necessary for continuity:
mechanical fittings (compression, bell & spigot, rebar etc.)
▶ Impressed Current Anodes. Answer: graphite
cast iron (high silicon chromium)
mixed metal oxides
scrap iron
conductive polymer
cylindrical, tubular
soil..... backfilled in coke breeze
▶ current span. Answer: current in a pipe can be measured by taking a
voltage drop across a known length and either calibrating the section in
question or using resistance from tables.
unknown pipe size must be calibrated by using I/ deltamV or R= V/I using 4
wires
▶ Sacrificial anode types. Answer: magnesium
zinc
cylindrical, bullet, ribbon, bracelet
soil backfilled in gypsum, bentonite mixture to reduce contact resistance to
soil and to retain moisture
make sure to remove plastic shipping bag
