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In every circuit there will be resistor(s) and generator(s), their number the numbers of which will the depend of the power requisites. Both components can be grouped depending on the what is required to keep constant, the current or the voltage. There are two basic ways to groups components in series or in parallel. (additional information in connecting batteries section)


The basic idea of a “series” connection is that components are connected end-to-end in a line to form a single path through which current can flow:

  1. Current: The amount of current is the same through any component in a series circuit.
  2. Resistance: The total resistance of any series circuit is equal to the sum of the individual resistances.
  3. Voltage: The supply voltage in a series circuit is equal to the sum of the individual voltage drops.


The basic idea of a “parallel” connection , on the other hand, is that all components are connected across each other’s leads. In a purely parallel circuit, there are never more than two sets of electrically common points, no matter how many components are connected. There are many paths for current flow, but only one voltage across all components:

  1. Voltage: Voltage is equal across all components in a parallel circuit.
  2. Current: The total circuit current is equal to the sum of the individual branch currents.
  3. Resistance: Individual resistances diminish to equal a smaller total resistance rather than add to make the total.


What ties all the components together in an electrical system are the cables. Cables supply the power to run appliances, and from the power sources for distribution to appliances, lights and equipment. Unfortunately, the most common installation error is to under-size cables relative to the load/s or from the recharge sources.

Proper installation is primarily a matter of sizing a cable to match its task, using the correct tools to attach terminals, and providing adequate over-current protection with fuses and circuit breakers. Cable sizing is fairly simple enough. It ; it is a function of the length of a cable ( measuring from the power source to the appliance and back), and the current (amperage) that will flow through it.

The longer the cable, or the higher the amperage, the bigger the cable must be to avoid unacceptable voltage losses. And there There should always be plenty of extra margin for safety because an appliance may actually use more current than what it is rated for because of heat, low voltage, extra load, or other factors. There’s never a performance penalty if a cable is marginally oversized; there is always a performance penalty (- and possibly a safety hazard ) - if it’s undersized.

The ground (negative) cable is as much a part of a circuit as the positive cable; it must be sized the same. In general, each appliance should be supplied from the distribution panel with its own positive and negative cables, although lighting circuits sometimes use common supply and ground cables to feed a number of lights (in which case the supply cables must be sized for the total load of all the lights). For 24v systems, the cables size is half that of a 12v setup. Always read product recommendations, or check with the supplier to know and understand exactly what size cable is required for the products.