Wire

Product and Ordering Information

Technical Data

Limits of Error

ANSI Limits of Error
Thermo Sensors' thermocouple and extension wires are known for their quality performance and reliability. Careful attention is given to the proper selection and matching of conductors to ensure conformance to standard limits of error as defined in ANSI C96.1*. Tables on this page show the limits of error for both thermocouple and extension grade wires. Unless otherwise specified, all wire will be furnished to standard limits of error. Many of the wires are available with special limits of error and must be specified when ordering.

Thermo Sensors provides a calibration service for customers who require known deviations from specified temperature points. Each coil or spool of wire so certified is marked and a "Certificate of Calibration" is furnished. Certification temperatures available are -320°F, -110°F, 32°F, and 2000°F and must be specified by the customer. All equipment used in the certification is traceable tot he National Bureau of Standards.

*The American National Standards Institute (ANSI) designations have replaced the previous Instrument Society of America (ISA) designations for thermocouple materials. ANSI Standard C96.1-1975, or latest version, is the applicable standard for wires listed in this catalog unless otherwise noted.

Limits of Error for Thermocouple Wire
Reference Junction at 32°F

Type Temperature Range Limits of Error
Standard
(whichever is greater)
Special
(whichever is greater)
T 0 to 350°C
32 to 662°F
± 1°C
± 2°F
or ± .75% ± .5°C
± 1°F
or ± .4%
J 0 to 750°C
32 to 1382°F
± 2.2°C
± 4°F
or ± .75% ± 1.1°C
± 2°F
or ± .4%
E 0 to 900°C
32 to 1652°F
± 1.7°C
± 3°F
or ± .5% ± 1°C
± 2°F
or ± .4%
K 0 to 1250°C
32 to 2202°F
± 2.2°C
± 4°F
or ± .75% ± 1.1°C
± 2°F
or ± .4%
R, S 0 to 1450°C
32 to 2642°F
± 1.5°C
± 3°F
or ± .25% ± .6°C
± .1°F
or ± .1%
B 800 to 1700°C
1472 to 3092°F
± .5°      

Sub-Zero Limits of Error
Thermocouple materials are normally supplied to meet the limits of error specified in the table for temperatures above 0°C. These materials, however, may not fall within the sub-zero limits of error given in the following table. If materials are required to meet the sub-zero limits, the purchase order must so state. Special pricing for selection of materials will be required.

T -200 to 0°C
-328 to 32°F
± 1°C
± 2°F
or ± 1.5%
E -200 to 0°C
-328 to 32°F
± 1.7°C
± 3°F
or ± 1%
K -200 to 0°C
-328 to 32°F
± 2.2°C
± 4°F
or ± 2%

Little information is available to justify establishing special limits of error for sub-zero temperatures. Limited experience suggests the following limits for types E and T thermocouples.

E -200 to 0°C
-328 to 32°F
± 1°C
± 2°F
or ± .5%
T -200 to 0°C
-328 to 32°F
± .5°C
± 1°F
or ± .8%

These limits are given only as a guide. Due to the characteristics of the materials, sub-zero limits of error for Type J thermocouples and special sub-zero limits for Type K thermocouples are not listed.

Limits of Error for Extension Wire
Reference Junction at 32°F

Type Temperature Range Limits of Error
Standard Special
KX 0 to 200°C
32 to 392°F
± 2.2°C
± 4°F
 
JX 0 to 200°C
32 to 392°F
± 2.2°C
± 4°F
± 1.1°C
± 2°F
EX 0 to 200°C
32 to 392°F
± 1.7°C
± 3°F
 
TX -60 to 100°C
-76 to 212°F
± 1°C
± 2°F
± .5°C
± 1°F

Limits of Error for Thermocouple Compensating Extension Wire
Reference Junction at 32°F

Compensating Type Thermocouple Type Temperature Range Limits of Error
RSX R, S 0 to 200°C
32 to 382°F
± 5°C
± 9°F
BX B 0 to 100°C
32 to 212°F
± 0°C     -3.7°C*
± 0°F     -6.7°F*

*Due to the non-linearity of the types of R, S, and B temperature - EMF curves, the error introduced into a thermocouple system by the compensating wire will be variable when expressed in degrees. The limits of error given in the table above are based on the following measuring junction temperatures:

Type Wire Measuring Junction Temperature
RSX Greater Than 870°C (1596°F)
BX Greater Than 1000°C (1832°F)

Noise Sheilding

Wire for Electromagnetic and Electrostatic Noise Shielding
Electromagnetic Noise is produced due to capacitive coupling of an electric field within the plant to the instrument circuit. The source of these electric fields may be power lines or other voltage sources mentioned below. The most effective means of isolating static noise is to have the instrument circuit enclosed within a 100% coverage shield such as an aluminum backed mylar tape. a drain wire in contact with the aluminum foil carries the interference to the ground.

Magnetic Noise is generated anytime a loop of instrument wires pass through a magnetic field. As the wires come in the stray magnetic field of an electric motor, generator, power line, relay or similar source, a current is produced in the instrument circuit to oppose the magnetic field. That current super-imposed on the sensor signal results in an erroneous and usually unstable signal input at the instrument.

Electrostatic and magnetic noise sources include but are not limited to the following conditions:
Circuits near:

  • Power lines
  • Medium sized (SHP) and larger motors
  • Control relays
  • Transformers
  • electrolytic processes
  • Induction heating equipment

To minimize the effects of electrostatic and magnetic noise, the use of Thermo Sensors' type PPZS extension wire is suggested. It incorporates both twisting, 100% shielding with an Aluminum/Mylar tape and drain wire. These wires are listed in the appropriate extension wire table.


ANSI Designations

ANSI Letter Designations
The tables listed below are provided to the user for a ready reference of ANSI designations as compared to the generic and trade names for the most common thermocouple materials. The letter "P" in the designation indicates the positive (+) leg of the calibration while the letter "N" designates the negative (-). Color coding and other means of conductor identification are also provided.

Thermocouple Grade Wire

ANSI Type Grade or Generic Trade Names* Single Conductors Magnetic Conductor Color Code Overall Color Code**
E Chromel
Constantan
EP
EN
No
No
Purple
Red
Brown w/ Purple Tracer
J Iron
Constantan
JP
JN
Yes
No
White
Red
Brown w/ White Tracer
K Chromel
Alumel
KP
KN
No
Yes
Yellow
Red
Brown w/ Yellow Tracer
T Copper
Constantan
TP
TN
No
No
Blue
Red
Brown w/ Blue Tracer

Extension Grade Wire

ANSI Type Grade or Generic Trade Names* Single Conductors Magnetic Conductor Color Code Overall Color Code**
EX Chromel
Constantan
EPX
ENX
No
No
Purple
Red
Purple
JX Iron Constantan JPX
JNX
Yes
No
White
Red
Black
KX Chromel
Alumel
KPX
KNX
No
Yes
Yellow
Red
Yellow
TX Copper
Constantan
TPX
TNX
No
No
Blue
Red
Blue
RX Copper
Alloy #11
RPX
RNX
No
No
Black
Red
Green
SX Copper
Alloy #11
SPX
SNX
No
No
Black
Red
Green
BX Copper
Copper
BPX
BNX
No
No
Gray
Red
Gray
W325X*** Alloy 203
Alloy 225
W3FX
W25NX
No
Yes
Orange
Red
Orange w/ Black Tracer
WS26X Alloy 405
Alloy 426
WSPX
W26NX
Yes
Yes
Orange
Red
Orange

*Trade names: Chromel, Alumel, Constantan - Hoekins Mfg. Co.

**Color Coding: Capton insulations will have a color fiber tracer under the Kapton singles. Overall insulations of Katpon and FEP are not color coded.
Some high temperature fibrous insultions are not color coded; others will have a colored tracer. The color pigment burns off at 300°F.

***Not ANSI Designations

Stranded Wire
Thermocouple and extension wires are usually solid conductors. When greater flexibility is needed, stranded wire is used. Both constructions are listed in the wire tables. The stranding combination used is given in the wire size column of the tables.