Purpose:
Relays provide a means to remotely control a circuit (i.e. turn a device on or off remotely). While this might seem to needlessly add complexity there are good reasons for using relays for this purpose.
| Safety | The load circuit might carry hazardously high voltage or current. It would be far safer to keep this danger off the panel. |
| Performance | The shorter the line, the less power lost. A relay installed in a line directly connecting the device and power source eliminates the length of wire ran back to a control panel and avoids the resulting power loss. |
| Cost Savings | Larger guage wire is costly. A relay can be an attractive option over the expense of additional heavy guage wire. |
| Space Constraints | Heavier guage wire does not tuck away as easily as lighter guage wire. It takes up more space and stiffness may make bends difficult. This can become a issue where space behind a dash or run under carpet or small conduit. |