Contact Us

Hours of Operation

Request Information

References


Reference

Tess HOME

 

                                     

MISCELLANEOUS REFERENCES

 Table for Type THWN & THHN Insulated Conductors

   

Conduit Sizes:

WIRE
SIZE

 

1/2

3/4

1

1-1/4

1-1/2

2

2-1/2

3

3-1/2

4

6

14
12
10
8
  13  
10  
6  
3  
24  
18  
11  
5  
39  
29  
18  
9  
69  
51  
32  
16  
94  
70  
44  
22  
154  
114  
73  
36  

164  
104  
51  


160  
79  



106  



136  
6
4
3
2
1
1  
1  
1  
1  

 

4  
2  
1  
1  
1  
6  
4  
3  
3  
1  
11  
7  
6  
5  
3  
15  
9  
8  
7  
5  
26  
16  
13  
11  
8  
37  
22  
19  
16  
12  
57  
35  
29  
25  
18  
76  
47  
39  
33  
25  
98  
60  
51  
43  
32  

137  
116  
97  
72  
0
00
000
0000
  1  
1  
1  
1  
1  
1  
1  
1  
3  
2  
1  
1  
4  
3  
3  
2  
7  
6  
5  
4  
10  
8  
7  
6  
15  
13  
11  
9  
21  
17  
14  
12  
27  
22  
18  
15  
61  
51  
42  
35  
250
300
350
400
    1  
1  
1  
 
1  
1  
1  
1  
1  
1  
1  
1  
3  
3  
2  
1  
4  
4  
3  
3  
7  
6  
5  
5  
10  
8  
7  
6  
12  
11  
9  
8  
28  
24  
21  
19  
500
600
750
      1  
1  
 
1  
1  
1  
1  
1  
1  
2  
1  
1  
4  
3  
2  
5  
4  
3  
7  
5  
4  
16  
13  
11  

 

Dimensions of EMT

Electrical Metallic Tubing

Trade Size in Inches

Outside Dia. in Inches

Inside Dia. in Inches

Wall Thickness in Inches

1/2

.706

.622

.042

3/4

.922

.824

.049

1

1.163

1.049

.057

1 1/4

1.510

1.380

.065

1 1/2

1.740

1.610

.065

2

2.197

2.067

.065

2 1/2

2.875

2.731

.072

3

3.500

3.356

.072

3 1/2

4.00

3.834

.083

4

4.500

4.334

.083

5

--

--

--

6

     

 

Dimensions of Rigid Conduit

Steel or Aluminum

Trade Size in inches

Outside Dia. in Inches

Inside Dia in Inches

Wall thickness in Inches

1/2

.840

.632

.104

3/4

1.050

.836

.107

1

1.315

1.060

.126

1 1/4

1.660

1.394

.133

1 1/2

1.900

1.624

.138

2

2.375

2.083

.146

2 1/2

2.875

2.489

.193

3

3.500

3.090

.205

3 1/2

4.00

3.570

.215

4

4.500

4.050

.225

5

5.563

5.073

.245

6

     
 

Dimensions of IMC

Intermediate Metal Conduit

Trade Size in Inches

Outside Dia. in Inches

Inside Dia. in Inches

Wall Thickness in Inches

1/2

.815

.675

.070

3/4

1.029

.879

.075

1

1.290

1.120

.085

1 1/4

1.638

1.468

.085

1 1/2

1.883

1.703

.090

2

2.360

2.170

.095

2 1/2

2.857

2.597

.130

3

3.476

3.216

.130

3 1/2

3.971

3.711

.130

4

4.466

4.206

.130

5

--

--

--

6

     
 

Dimensions of PVC

(Poly Vinyl Chloride) Conduit

SCHEDULE 40

Trade Size in Inches

Outside Dia. in Inches

Inside Dia. in Inches

Wall Thickness in Inches

1/2

.840

.622

.109

3/4

1.050 .824 .113

1

1.315 1.049 .133

1 1/4

1.660 1.380 .140

1 1/2

1.900 1.610 .145

2

2.375 2.067 .154

2 1/2

2.875 2.469 .203

3

3.500

3.068 .216

3 1/2

4.000

3.548 .226

4

4.500

4.206

.237

5

5.563

5.047

.258

6

 6.625  6.065

 .280

 

 

 
Series Direct Current Circuit Rules
 

 
Rule #1:  The same current flows through each part of a series circuit.
   
Rule #2:  Total Resistance of a series circuit is equal to the sum of the individual resistances.
   
Rule #3:  The total voltage across a series circuit is equal to the sum of the individual voltage drops.
   
 Rule #4:  The voltage drop across a resistor in a series circuit is proportional to the size of the resistor.
   
Rule #5:  The total power dissipated in a series circuit is equal to the sum of the individual power dissapations.


 

SUMMARY OF OHMS LAW FORMULAS
 

 
AMPERES   =   VOLTS
 RESISTANCE
   
RESISTANCE   =  VOLTS
 AMPERES
   
VOLTS   =  AMPERES x RESISTANCE
   

Parallel Direct Current Circuit Rules

 


 
Rule #1:  The same voltage exists across each branch  of a parallel circuit and is equal to the source voltage.
   
 Rule #2:  The current through a branch of a parallel network is inversely proportional to the amount of resistance of the branch.
   
Rule #3:  The total current of a parallel circuit is equal to the sum of the currents of the individual branches of the circuit.
   
 Rule #4:  The total resistance of a parallel circuit is equal to the reciprocal of the sum of the reciprocals of the individual resistances of the circuit.
   
 Rule #5:  The total power dissipated in a parallel circuit is equal to the sum of the individual power dissapations.

 

SUMMARY OF PARALLEL CIRCUIT RULES
 

 
TOTAL VOLTAGE =  E(1) = E(2) = E(3) ...etc.
   
 TOTAL RESISTANCE =  VOLTS
 AMPERES
   
   


 
TO DETERMINE THE TOTAL RESISTANCE IN A PARALLEL CIRCUIT WHEN THE TOTAL CURRENT AND TOTAL VOLTAGE ARE UNKNOWN USE EITHER OF THE FOLLOWING FORMULAS:

 
 
RT                1 
___________________
   + + + ......etc
   R1  R2   R3 
   
FOR TWO RESISTORS IN PARALLEL USE THIS FORMULA CALLED THE "PRODUCT OVER THE SUM"  
   
 RT =    R(1) * R(2) 
  R(1) + R(2)
   

POWER IN SINGLE PHASE RESISTIVE CIRCUITS
WHERE POWER FACTOR IS 100 PERCENT
(THESE FORMULAS ARE COMMONLY USED TO SOLVE MOST CIRCUIT POWER PROBLEMS ON TESTS)

TO DETERMINE THE POWER CONSUMED BY AN INDIVIDUAL RESISTOR IN A SERIES CIRCUIT USE THIS FORMULA:
 

POWER  I2 x R

TO DETERMINE THE POWER CONSUMED BY AN INDIVIDUAL RESISTOR IN A PARALLEL CIRCUIT USE THIS FORMULA:
 

POWER  E2
 R

TO DETERMINE THE TOTAL POWER CONSUMED BY AN INDIVIDUAL CIRCUIT USE THIS FORMULA:

POWER = E (TOTAL VOLTAGE)  x  I (TOTAL CURRENT)
 
 
 

 



RULES OF THUMB:

  • THE TOTAL RESISTANCE OF RESISTORS IN PARALLEL IS ALWAYS LESS THAN THE VALUE OF ANY ONE RESISTOR.
  • THE TOTAL RESISTANCE OF PARALLEL RESISTORS THAT ARE ALL THE SAME VALUE IS THAT VALUE DIVIDED BY THE NUMBER OF RESISTORS.
  • ALWAYS USE THE PRODUCT OVER SUM RULE TO BREAK DOWN TWO PARALLEL RESISTORS INTO ONE RESISTOR.  THIS IS MUCH EASIER THAN TRYING TO SOLVE LARGE ALGEBRAIC EXPRESSIONS.
  • 746 WATTS IS EQUAL TO ONE HORSEPOWER
  • EFFICIENCY IS EQUAL TO OUTPUT DIVIDED BY INPUT
  • IN INDUCTIVE CIRCUITS CURRENT LAGS VOLTAGE.
  • IN CAPACITIVE CIRCUITS CURRENT LEADS VOLTAGE.
  • POWER FACTOR IS A MEASURE OF HOW FAR CURRENT LEADS OR LAGS VOLTAGE.


 



POWER IN ALTERNATING CURRENT CIRCUITS WHERE POWER FACTOR IS NOT 100 PERCENT

POWER = E x I x POWER FACTOR (FOR SINGLE PHASE)

POWER = E x I x 1.732 X POWER FACTOR (FOR THREE PHASE)

THIS POWER IS ALSO CALLED TRUE POWER OR REAL POWER AS OPPOSED TO APPARENT POWER FOUND BY CALCULATING VOLT-AMPERES.

VOLT-AMPERES = E x I (FOR SINGLE PHASE)

VOLT-AMPERES = E x I x 1.732 (FOR THREE PHASE)

IT CAN READILY BE DETERMINED BY ALGEBRA THAT

 
 

 
POWER FACTOR
     TRUE POWER 
 APPARENT POWER

 


MOTOR APPLICATION FORMULAS

 
 

 
HORSEPOWER =
(for three phase motors) 
     1.732 x VOLTS x AMPERES x EFFICIENCY x   power factor
                746
 
 

 
THREE PHASE AMPERES
(for three phase motors) 
                  746 x HORSEPOWER 
   1.732 x VOLTS x EFFICIENCY x POWER FACTOR
 
 

 
SYNCHRONOUS RPM
              HERTZ x 120 
     NUMBER OF POLES

 


MOTOR MARKINGS AND CONNECTIONS
CONNECTIONS FOR NINE LEAD
THREE PHASE MOTORS

THREE PHASE STAR OR Y


 
 

STAR CONNECTED
 

 

Voltage

Line 1

Line 2

Line 3

Together

Low

1 & 7

2 & 8

3 & 9

4 & 5 & 6

High

1

2

3

4 & 7, 5 & 8, 6 & 9


 

THREE PHASE DELTA
 
 


 

DELTA CONNECTED
 

 

Voltage

Line 1

Line 2

Line 3

Together

Low

1 & 6 & 7

2 & 4 & 8

3 & 5 & 9

NONE

High

1

2

3

4 & 7, 5 & 8, 6 & 9

DELTA WYE HOOKUP FOR TRANSFORMER


 

MOTOR CONTROLLER WITH THREE
START STOP STATIONS
(HOLDING CONTACTS NOT SHOWN)

TRANSFORMER TURNS RATIO

     Ep   Tp
     Es        Ts

Where
Ep is primary voltage
Es is secondary voltage
Tp is number of turns in primary
Ts is number of turns in secondary

Delta and Wye Circuit Equations

 

Typical 3-Phase Wiring Diagrams and Equations for Resistive Heaters

Definitions

For Both Wye and Delta
(Balanced Loads)

VP = Phase Voltage
VL = Line Voltage
IP = Phase Current
IL = Line Current
R = R1 = R2 = R3 = Resistance of each branch
W = Wattage

Wye and Delta Equivalent
WDELTA = 3 WWYE

Open 3-Phase Circuit Formulas:
Open Delta Watts = 2/3 WDELTA
Open Wye Watts = 1/2 WWYE
Open 4-wire Wye Watts = 2/3 WWYE

3-Phase Wye
(Balanced Load)

3-Phase Open Wye
(No Neutral)

IP = I L
VP = VL/1.73
WWYE = VL2 /R = 3 (VP2) /R
WWYE = 1.73VLIL
IPO = I LO
VPO = VL/2
WOWYE = 1/2 ( VL /R)
WOWYE = 2 (VPO2/R)
WOWYE = VLILO
 

3-Phase Delta
(Balanced Load)

IP = I L/1.73
VP = VL
WDELTA = 3(VL2)/R
WDELTA = 1.73VLIL
 

3-Phase Open Delta
.
 

VP = VL
IPO1 = I PO3 = I LO2
ILO3 = 1.73 I PO1
WODELTA = 2(VL2/R )
 

 

Fractional/Decimal/Millimeter Conversion
Fraction Decimal Millimeter Fraction Decimal Millimeter MM Inch
1/64 - .015625 - 0.397

1/32 - .03125 - 0.794

3/64 - .046875 - 1.191

1/16 - .0625 - 1.588

5/64 - .078125 - 1.984

3/32 - .09375 - 2.381

7/64 - .109375 - 2.778

1/8 - .125 - 3.175

9/64 - .140625 - 3.572

5/32 - .15625 - 3.969

11/64 - .171875 - 4.366

3/16 - .1875 - 4.762

13/64 - .203125 - 5.129

7/32 - .21875 - 5.556

15/64 - .234375 - 5.953

1/4 - .25 - 6.350

17/64 - .265625 - 6.747

9/32 - .28125 - 7.144

19/64 - .296875 - 7.541

5/16 - .3125 - 7.938

21/64 - .328125 - 8.334

11/32 - .34375 - 8.731

23/64 - .359375 - 9.128

3/8 - .375 - 9.525

25/64 - .390625 - 9.921

13/32 - .40625 - 10.319

27/64 - .421875 - 10.716

7/16 - .4375 - 11.112

29/64 - .453125 - 11.509

15/32 - .46875 - 11.906

31/64 - .484375 - 12.303

1/2 - .5 - .12.700

33/64 - .515625 - 13.097

17/32 - .53125 - 13.494

35/64 - .546875 - 13.891

9/16 - .5625 - 14.288

37/64 - .578125 - 14.684

19/32 - .59375 - 15.081

39/64 - .609375 - 15.478

5/8 - .625 - 15.875

41/64 - .640625 - 16.272

21/32 - .65625 - 16.669

43/64 - .671875 - 17.066

11/16 - .6875 - 17.462

45/64 - .703125 - 17.859

23/32 - .71875 - 18.256

47/64 - .734375 - 18.653

3/4 - .75 - 19.050

49/64 - .765625 - 19.447

25/32 - .78125 - 19.844

51/64 - .796875 - 20.241

13/16 - .8125 - 20.638

53/64 - .828125 - 21.034

27/32 - .84375 - 21.431

55/64 - .859375 - 21.828

7/8 - .875 - 22.225

57/64 - .890625 - 22.622

29/32 - .90625 - 23.019

59/64 - .921875 - 23.416

15/16 - .9375 - 23.812

61/64 - .953125 - 24.209

31/32 - .96875 - 24.606

63/64 - .984375 - 25.003

1 - 1. - 25.400

1 - .039

2 - .0790

3 - .1181

4 - .1575

5 - .1969

6 - .2362

7 - .2756

8 - .3150

9 - .3543

10 - .3937

11 - .4331

12 - .4724

13 - .5119

14 - .5519

15 - .5906

16 - .6300

17 - .6693

18 - .7087

19 - .7480

20 - .7874

21 - .8268

22 - .8661

23 - .9055

24 - .9449

25 - .9843

 

 

 
 

Maximum Horsepower
for NEMA-Rated
Motor Starters

 

Single-Phase

Three-Phase

NEMA
Size

115
Volt
230
Volt
208/230
Volt
460/575
Volt

00

1/3 1 1.5 

0

1 2

1

2 3 7.5  10 

2

3 7.5 10/15  25 

3

  25/30  50 

4

40/50  100 

5

75/100  200 
 

NEMA RATING FOR ENCLOSURES

NEMA and other organizations have established standards of enclosure construction for control equipment. In general, equipment would be enclosed for one or more of the following reasons:

  1. Prevent accidental contact with live parts.
  2. Protect the control from harmful environmental conditions.
  3. Prevent explosion or fires which might result from the electrical arc caused by the control.

Common types of enclosures per NEMA classification numbers are:

NEMA I - GENERAL PURPOSE

The general purpose enclosure is intended primarily to prevent accidental contact with the enclosed apparatus. It is suitable for general purpose applications indoors where it is not exposed to unusual service conditions. A NEMA I enclosure serves as protection against dust and light indirect splashing, but is not dusttight.

NEMA 3 - DUSTTIGHT, RAINTIGHT

This enclosure is intended to provide suitable protection against specified weather hazards. A NEMA 3 enclosure is suitable for application outdoors, on ship docks, canal and construction work, and for application in subways and tunnels. It is also sleet-resistant.

NEMA 3R - RAINPROOF, SLEET RESISTANT

This enclosure protects against interference in operation of the contained equipment due to rain, and resists damage from exposure to sleet. It is designed with conduit hubs and external mounting, as well as drainage provisions.

NEMA 4 - WATERTIGHT

A watertight enclosure is designed to meet the hose test described in the following note: "Enclosures shall be tested by subjection to a stream of water. A hose with a one inch nozzle shall be used and shall deliver at least 65 gallons per minute. The water shall be directed on the enclosure from a distance of not less than 10 feet and for a period of five minutes. During this period it may be directed in any one or more directions as desired. There shall be no leakage of water into the enclosure under these conditions."

A NEMA 4 enclosure is suitable for applications outdoors on ship docks and in dairies, breweries, etc.

NEMA 4X - WATERTIGHT, CORROSION-RESISTANT

These enclosures are generally constructed along the lines of NEMA 4 enclosures except they are made of a material that is highly resistant to corrosion. For this reason, they are ideal in applications such as paper mills, meat packing, fertilizer and chemical plants where contaminants would ordinarily destroy a steel enclosure over a period of time.

NEMA 7 - HAZARDOUS LOCATIONS - CLASS I

These enclosures are designed to meet the application requirements of the National Electrical Code for Class I hazardous locations. In this type of equipment, the circuit interruption occurs in air.

"Class I locations are those in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures."

NEMA 9 HAZARDOUS LOCATIONS - CLASS II

These enclosures are designed to meet the application requirements of the National Electrical Code for Class II hazardous locations.

"Class II locations are those which are hazardous because of the presence of combustible dust."

The letter or letters following the type number indicates the particular group or groups of hazardous locations (as defined in the National Electrical Code) for which the enclosure is designed. The designation is incomplete without a suffix letter or letters.

NEMA 12 - INDUSTRIAL USE

The NEMA 12 enclosure is designed for use in those industries where it is desired to exclude such materials as dust, lint, fibers and flyings, oil see page or coolant see page. There are no conduit openings or knockouts in the enclosure, and mounting is by means of flanges or mounting feet.

NEMA 13 - OILTIGHT, DUSTTIGHT

NEMA 13 enclosures are generally of cast construction, gasketed to permit use in the same environments as NEMA 12 devices. The essential difference is that, due to its cast housing, a conduit entry is provided as an integral part of the NEMA 13 enclosure, and mounting is by means of blind holes, rather than mounting brackets.

 

Rules for Reading the National Electrical Code

 
  When using the NEC it is important to remember the arrangement of the Code as found in Section 90-3 in the Introduction. If these rules and the rules published by the International Association of Electrical Inspectors are adhered to, many incorrect interpretations can be avoided. Below is a list of the rules that everyone reading the NEC should know.

 

  1. Chapters 1 through 4 apply generally except as modified or amended by Chapters 5 through 7.
  2. Chapter 8 on communications systems (telephone, telegraph, radio and television equipment, and community antenna systems) is a stand alone chapter and is independent of the other chapters except where they are specifically referenced in chapter 8.
  3. When a chapter is divided into parts, Part A - General applies to all the other parts which are independent of each other.
  4. When sections are referenced always read the title to the section. The section rules apply within the scope of the heading or subheading only. Also, exceptions apply only to the subheading which they follow.
  5. Article 110, requirements for electrical installations applies to all other articles of the code.
  6. Fine print notes, [FPN], are explanations and are not mandatory rules.
  7. Mandatory rules are worded with "shall." Where the word "May" is used the authority having jurisdiction may or may not grant permission.

Most electrical people will find the NEC much easier to read if they will remember these rules.

 

 

   
 

Inventory Quantities are updated daily BUT sales are ongoing. Check with us to reserve Your Requirements.