Calculated Industries ElectriCalc LT User manual

ElectriCalc
®
LT
An Electrician's Utility for Wiring
User's Guide

IMPORTANT NOTE ON
USER RESPONSIBILITY
Due to the serious nature of electrical
installations, the user of this calculator
must be certain that he or she is using it
correctly, i.e., in accordance with both
the following instructions and National
Electrical Code®requirements.
This tool was designed to work with the
1999 NEC®, not replace it. Users, espe-
cially those unfamiliar with the Code,
should exercise appropriate caution.
If questions arise as to the correctness
of an answer given by the calculator, or
if an answer appears to conflict with the
Code, the user should always defer to
the Code.
If used responsibly and correctly, this
tool will save the user hours of tedious
calculation and look-up time, reduce
material costs, and provide safe, accu-
rate, Code-legal answers.
National Electrical Code and NEC are
registered trademarks of the National
Fire Protection Association, Inc.,
Quincy, MA 02269

User's Guide — 1
Introducing the
ElectriCalc®LT
The
ElectriCalc
®
LT
is an invaluable
calculator for today’s busy electrical
professional. Unlike a regular calculator,
it has intuitively labeled “electrical keys”
and conforms to the 1999
National
Electrical Code,
allowing you to solve
Code-related problems quickly and
accurately. Common NEC tables are
built in, providing instant solutions for
the following:
♦Volts, Amps, Volt-Amps, Watts,
kVA, kW, PF%, EFF%, and DC
Resistance
♦Copper or Aluminum Wire Sizes
♦Parallel & Derated Wire Sizes
♦Voltage Drop Wire Sizes, % and
Actual Voltage Drops, Voltage
Drop Distances and Wire Resis-
tances
♦Grounding Conductors Sizes
♦And much more!

2 — ElectriCalc LT
Table of Contents
Key Definitions
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3
Default Settings
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16
Basic Math Operations
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17
Percent Calculations
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17
Memory Functions
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18
Kerchoff’s Law
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19
Ampacity Wire Sizing
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24
Voltage Drop
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31
Error Codes
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39
1999 NEC References
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39
Battery Information
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40
Settings
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40
Warranty
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41
Legal Notices
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45

User's Guide — 3
Key Definitions
Standard Calculator Functions
[On/C] — On/Clear
Turns on power. Pressing once clears
the last entry and the display. Pressing
twice clears all non-permanent values.
[Off] — Off
Turns all power off. Clears the memory
and most internal registers.
[Set] — Second Function
Accesses the secondary functions
shown above the keys when pressed
prior to selection.
[Rcl] — Recall
Recalls a value stored in a register
(e.g., to recall voltage drop % press
[Rcl] [VD%]).
[Rcl] [Rcl] — Display/Clear Memory
Displays and clears the value saved in
(M+).
[Set] [Rcl] — Clear Memory
Clears the value saved in [M+] without
changing displayed value.

4 — ElectriCalc LT
[M+] — Cumulative Memory
Adds displayed value to Memory (e.g.,
10 [M+], 20 [M+], [Rcl] [M+] = 30).
Clears when the calculator is shut off.
[Set] [M+] — Memory Minus (M−)
Subtracts the displayed value from
Memory.
[+] [–] [x] [÷] [=]
Arithmetic operation keys.
[Set] [–] — Change Sign (+/–)
Toggles the sign of the displayed value
(from positive to negative or from nega-
tive to positive).
[Set] [÷] — Reciprocal (1/x)
Reciprocal, or 1/x function.
[0] – [9] & [ • ]
Digits used for keying in numbers.
[Set] [ . ] — x2
Squares the displayed value.
[%] — Percent
Four function percent key.
[Set] [%] — Square Root ( x )
Square root function.

User's Guide — 5
Mode "Set-Up" Functions
[Set] [x] — All-Clear (AC)
Resets all settings and values to their
default settings.
[CU/AL] — Copper/Aluminum
Used to toggle between copper (default)
and aluminum wire types. When the
wire type is revised, any calculated wire
size will be re-calculated automatically.
If a wire size is entered with the wrong
wire type, pressing [CU/AL] will change
the material type without changing the
size.
Displays: Al or Cu
[Set] [1] — Single-Phase (1Ø)
Sets calculator to single-phase mode.
Displays: 1Ø.
[Set] [3] — Three-Phase (3Ø)
Sets calculator to three-phase mode.
Displays: 3Ø.
[Set] [6] — 60°C Wire Insulation
Sets calculator to 60°C wire insulation
type for wire size calculations. This is
the default setting. Displays: 60.
[Set] [7] — 75°C Wire Insulation
Sets calculator to 75°C insulation type
for wire size calculations. Displays: 75.

6 — ElectriCalc LT
[Set] [9] — 90°C Wire Insulation
Sets calculator to 90°C insulation type
for wire size calculations. Displays: 90.
[Set] [2] — Ambient Temperature
Permanently enters ambient tempera-
ture for determining ampacity derived
wire sizes. Ambient temperature will
only change when entering a new value
or by resetting the calculator ([Set] [x]).
Defaults to 30°C (86°F). Amb° will dis-
play when the ambient temperature is
other than 30°C (86°F).
Displays: Amb°.
[Set] [4] — Feet/Meters Toggle
Toggles between feet and meters.
Displays: FEET or MET.
[Set] [5] — Free Air (FrAir)
Sets calculator into Free Air mode,
which refers to NEC Table 310-17 for
wire size calculations. Revises back to
Raceway mode when calculator is pow-
ered down. Displays: FrAir.
[Set] [+] — °C/°F Toggle
Toggles ambient temperature format
between °C and °F. Converts displayed
temperature value automatically.
Displays: °C or °F.

User's Guide — 7
Electrical Functions
[kilo-] — Kilo-
This key is used with watts, amps, volts,
and volt-amps to identify "kilo-" values.
[Set] [kilo-] — Milli-
This key is used with other keys watts,
amps, volts, and volt-amps to identify
"milli-" values.
[Amps] — Amps
Enters or calculates amps (using volts
and VA or watts). Displays: AMPS,
KAMP.
[Volts] — Volts
Enters or calculates volts (using amps,
HPth, and VA or watts). Default value is
240 volts. Displays: VOLT, KV, or mV.
[Set] [Volts] — DC Resistance
Calculates and displays DC resistance.
Displays: OHMS.
[VA] — Volt-Amps
Enters or calculates volt-amps (using
amps, volts and horsepower or watts).
Displays: VA, KVA, or mVA.

8 — ElectriCalc LT
[Watts] — Watts
Enters or calculates watts (using amps,
volts, and VA or horsepower).
Displays: WATT, KW, or mW.
[Set] [Watts] —Power Factor
Enters or calculates power factor per-
centage (based on watts and VA). De-
faults to 100%. Entered or calculated
power factors greater than 100% will
result in an error. Displays: PF%.
[HPth] — Horsepower (Theoretical)
Enters or calculates theoretical horse-
power (based on Amps, VA, watts, effi-
ciency%, PF%, and/or volts). 1.0 HPth
correlates to 746 watts at 100% effi-
ciency. Displays: HPth.
NOTE: This horsepower should not be
confused with the motor horsepower
keys used to determine motor load.
[Set] [HPth] — Efficiency
Enters or calculates the percent ratio
between real power (watts) and theo-
retical horsepower. Default: 100%. En-
tered or calculated efficiencies greater
than 100% will result in an error. Dis-
plays: EFF%.

User's Guide — 9
Ampacity Tables
The
ElectriCalc LT
uses NEC Table
310-16 (310-17 for Free Air) to find wire
sizes and ampacity ratings of wires. The
calculator uses the following data to
calculate wire size: 1) insulation tem-
perature rating (60°C, 75°C and 90°C),
2) wire material (copper or aluminum),
and 3) ambient temperature. Only stan-
dard AWG wire sizes are used by the
ElectriCalc LT.
NOTE: 1/0, 2/0, 3/0 and 4/0 wires are
entered using the [0] key (i.e., 0, 00, 000
and 0000).
[WireSz] — Wire Size/Ampacity
Enters or calculates wire size based on
ampacity and voltage drop, if a voltage
drop length has been entered.
♦
First Press
If a wire length has been entered, the
first press will show the larger of the
ampacity or voltage drop derived wire
size. The calculator will use the larger
value when calculations require a wire
size. If no voltage drop length has been
entered, the calculator will display the
calculated ampacity rated wire size.

10 — ElectriCalc LT
♦
Second Press
If a wire length has been entered, the
second press displays the smaller of the
two wire sizes. If not solving for voltage
drop wire size, then displays the maxi-
mum ampacity.
♦
Third Press
If a wire length has been entered, dis-
plays the minimum wire ampacity rating.
[Set] [WireSz] — 125% Ampacity
Operates same as [WireSz], except that
a factor of 125% is applied to the am-
perage.
[ParSz] — Parallel Size
Used to find the size of parallel con-
ductors using amperage and an entered
quantity of wires. Parallel wire size
computations smaller than 1/0 are dis-
played as “nonE” as the NEC does not
allow parallel wire runs smaller than 1/0.
NOTE: No adjustments are made for
deration
♦
.First Press
When preceded by a number, calcu-
lates the applicable wire size for that
quantity of wires in parallel.
Displays: PAR WIRE SIZE.
♦
Second Press

User's Guide — 11
Displays the maximum adjusted am-
pacity of the calculated parallel wire
size. Displays: WIRE A.
NOTE: Some areas may not allow par-
alleling conductors. Users must know
the jurisdiction requirements for their
area.
[Set] [ParSz] — Derated Wire Size
Used to calculate derated wire sizes
and allowable ampacity based on the
entered quantity of wires, NEC Table
310-16 and NEC Table 310-15(b)(2)(a).
Derated wire sizes are not calculated
when there are less than 4 wires, or
when the unit is in Free Air mode.
♦
First Press
Calculates the derated wire size, if you
have entered the number of wires, for
example, 4 [Set] [ParSz]).
Displays: D/R WIRE SIZE
♦
Second Press
Displays the maximum adjusted am-
pacity of the derated wire size.
Displays: D/R WIRE A
♦
Third Press
Displays the derated adjustment factor
per the NEC Table 310-15(b)(2)(a).
Displays: ADJ %

12 — ElectriCalc LT
Voltage Drop Solutions
The
ElectriCalc LT
will calculate maxi-
mum lengths, minimum wire sizes or
actual voltage drops given the other two
values. Voltage drop solutions are
based on the DC resistance values
found in NEC Chapter 9, Table 8.
NOTE: Voltage drop solutions may vary
slightly from actual AC circuit values as
factors such as inductive reactance,
skin effect, raceway material, etc., are
not considered
[VD%] — Percent Voltage Drop
Used to enter or calculate voltage drop.
The default voltage drop is 3%. If wire
size or wire length values are not avail-
able, “nonE” will display since the volt-
age drop cannot be found.
♦
First Press
Enters a maximum allowable voltage
drop percentage (Displays: V DROP
%) or calculates actual voltage drop
Displays: V DROP
♦
Second Press
Calculates actual percent voltage drop.
Displays: V DROP %

User's Guide — 13
[Length] — Length
Enters or calculates the maximum
length of run for voltage drop computa-
tion. Displays: FEET or MET
[Set] [Length] — Wire Resistance
Displays the wire resistance per 1,000
feet of the wire size in [WireSz] based
on NEC Chapter 9, Table 8.
Displays: OHMS WIRE

14 — ElectriCalc LT
Ground Function Keys
[Grnd] — Ground
An output-only key used to find the
grounding electrode conductor size for
AC systems based on NEC Table
250-66 and an entered or calculated
service-entrance conductor (largest
size). Only actual wire sizes are consid-
ered valid entries.
♦
First Press
Calculates the copper grounding elec-
trode conductor size if you have entered
a valid wire size.
Displays: GRND CU WIRE SIZE
♦
Second Press
Displays the aluminum grounding elec-
trode conductor size.
Displays: GRND AL WIRE SIZE
♦
Third Press
Displays the circular mil area used to
calculate the grounding electrode con-
ductor size. Displays: CMIL WIRE

User's Guide — 15
[Set] [Grnd] — Equipment Ground
(EqGrnd)
This function uses NEC Table 250-122
to compute the minimum equipment
grounding conductor size, given an
entered amperage rating or setting for a
over-current device up line (i.e., 300
[Set] [Grnd]).
NOTE: This function deviates from the
NEC Table 250-122 for Amp values of
4001 or more. The AL conductor sizes
given in the Table (1200 MCM AL) are
not among those listed in Table 310-
16/17, which is the table the calculator
uses to calculate wire size. In these
cases, the calculator gives a slightly
larger 1250 MCM AL as the appropriate
Equipment Ground wire size.
♦
First Press
Displays the copper grounding conduc-
tor size for the entered amp rating.
Displays: EQPG WIRE SIZE CU
♦
Second Press
Displays the aluminum grounding con-
ductor size.
Displays: EQPG WIRE SIZE AL

16 — ElectriCalc LT
Default Settings
When you first receive your calculator, it
is pre-set to the default settings listed
below. You can always return your cal-
culator to these default values with an
All-Clear ([Set] [x]).
Ambient Temperature 30°C
Insulation Rating 60°C
Material Copper (Cu)
Phase 3Ø
Volts 240 V
Efficiency 100%
Power Factor 100%
Length Units Feet
Voltage Drop Percent 3%
Wire Environment Raceway
(vs Free Air)

User's Guide — 17
Basic Math Operations
This calculator uses standard chaining
logic, which simply means that you enter
your first value, the operator (+, –, x, ÷),
the second value and then the equals
sign (=).
A. 3 [+] 2 [=] 5
B. 3 [–] 2 [=] 1
C. 3 [x] 2 [=] 6
D. 3 [÷] 2 [=] 1.5
Percent Calculations
The percent key [%] can be used for
finding a given percentage of a number
or for working add-on, discount or divi-
sion percentage calculations.
355 [x] 15 [%] 53.25
250 [+] 6.5 [%] 266.25
25 [–] 5 [%] 23.75
100 [÷] 50 [%] 200.
The percent key also allows you to
change percentages to decimals (e.g.,
25 [%] 0.25).

18 — ElectriCalc LT
Memory Functions
Whenever the [M+] key is pressed, the
displayed value will be added to mem-
ory. Other memory functions:
Function Keystrokes
Subtract from memory [Set] [M+]
Recall total in memory [Rcl] [M+]
Display & clear memory [Rcl] [Rcl]
Clear memory, no display [Set] [Rcl]
Replace memory with
displayed value [Set] [Rcl] [M+]
The memory is semi-permanent; it will
be cleared when you:
1) turn off the calculator;
2) press [Rcl] [Rcl];
3) press [Set] [Rcl];
4) press [Set] [x] (all clear).
How To Use Memory Functions:
Steps Keystrokes Display
Add to M+ 355 [M+] 355.
Add to M+ 255 [M+] 255.
Recall total M+ [Rcl] [M+] 610.
Sub. from M+ 745 [Set] [M+] 745.
Recall & clear [Rcl] [Rcl] – 135