Power and Ground Distribution: Description and Operation

Ground points and oxidation

Environmental factors

Vibration, changes in temperature, gases and corrosive substances (such as road salt) subject cable connections to considerable stresses. Poorly executed connections or incorrectly sealed connectors result in reduced service life and lower quality.

Surface oxides

All metal surfaces oxidize in contact with air. This makes it important to fit a cable terminal on a stripped cable for crimping as soon as possible after stripping the cable.

Most cable terminals are tin plated. Tin oxidizes rapidly and the surface oxide coating makes a bard layer on the soft tin which cracks easily when a pin or socket is attached to create a contact.

The surface oxide around contact points protect build a gas tight joint which prevents further oxidation and provides a good electrical contact.

Ground points







The ground points on a car are a vital part of the car electrical system as all sub-system voltage levels have the ground point as a reference (0 V).

The illustration shows a ground point screw connection of the type found on the cylinder block (upper illustrations) and to the body (lower illustration). The arrowed lines show the path of the electric current through the contact point.

A poor contact on the ground point will have a negative impact on the car electrical systems. It is therefore very important that the ground point contact is in good order, that the screw is tight and the cable terminal is correctly crimped to the cable.

Especially important are ground points where several wires are connected to one ground point.

NOTE: There should be no oxidation between the cable terminals and the screw head.

Installation







Always clean around screws, nuts and contact surfaces.