Wire HarnessWire Harness Designing

Terminal selection Based on Series, Tab Size and Max Current Capacity

In last article,  Selection of Terminals in Wire Harness Design. We discussed about wire harness assembly and terminal manufacturers. The article also throw light on terminal selection parameters like compatibility with connector, Wire size range, application, conductivity and retention force. In this particular piece.We will focus on terminal series, tab size and maximum current capacity referred to industry performance criteria.

Terminal Series and Tab Size

Solderless terminals are used in automotive wire harness for better conductivity. At the same time soldering is costlier than crimped terminals. Selection of suitable terminals and crimping methodology is equally important and provides cost optimization. Besides, prevents loose contact due to vibrations in automobiles. Furthermore, being a new in wire harness design study, it becomes difficult to opt terminal without any guideline.

There are various types of terminals and series available in market. Hence, to understand properly let’s do an exercise. Visit terminal technology site. Here you will find not only various series but also various types of terminals. Purpose of terminal series is for proper design and manufacturing. In the same way, easy handling and meeting desire needs of a consumer becomes possible.

How to Read

Here we took an example of TT-1629, 110 series terminal. Its name is given in category number. Tab size is 2.80 x 0.50. If you see its diagram. You will find width of the terminal as 2.80 and thickness equal to 0.50.  In industry, people normally refer the terminal either in language of series or its tab size. Description helps to understand application of that specific terminal. Now TT-1829 is male terminal, whose applicable mating terminal is TT-1628 .

Male and Female Terminal, Courtesy Terminal Technology

Drawing of TT-1628 shown can give us more detail. Like, this terminal is best suitable for wire size 0.30 to 0.85 sq.mm. Material used is CuZn. If you see  its width it is 4.10 however, tab size is 2.80 x 0.50. Don’t get confuse here, tab size is always given with reference to male terminal for ease of understanding. Same is true for all series terminals. Following table gives us an easy understanding for terminal series and its respective tab size.

030 0.80
040 1.00
050 1.30
060 1.50
070 1.70
090 2.30
110 2.80
187 4.80
250 6.30
305 7.80
312 8.00
375 9.50

Maximum Current Capacity and Wire Size

Maximum current carrying capacity of terminal should be more than that of wire. The current carrying capacity of cable depends on many factor. It can be defined as the amperage a conductor can carry before melting either the conductor or the insulation. Heat, caused by an electrical current flowing through a conductor, will determine the amount of current a wire will handle. Theoretically, the amount of current that can be passed through a single bare copper conductor wire can be increased until the heat generated reaches the melting temperature of copper.

The following table details about terminal series, tab size, maximum current and required wire size. The suitable wire size for terminal is always mentioned by in terminal manufacturer catalog or diagram.

1 030 0.8 8 0.3 – 0.5
2 040 1.0 8 0.3 – 0.5
3 050 1.3 9 0.3 – 0.5
4 060 1.5 12 0.3 – 0.75
5 090 2.3 20 0.3 – 1.25
6 110 2.8 24 0.3 – 2.0
7 187 4.8 28 0.3 – 3.0
8 250 6.3 30 0.3 – 3.0
9 305 7.8 40 0.5 – 8.0
10 312 8.0 43 0.5 – 8.0



Whenever there is an option of choosing terminal between 250 series and 350 series type the following guideline should be checked,

For load up to 20 amperes and wire size upto 3 Sq.mm, 250 series terminal should be used. For load more than 20 amperes, 350 series terminal should be used.

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