On bonding:
Electrical bonding is the practice of intentionally electrically connecting all exposed metallic items not designed to carry electricity in a room or building as protection from electric shock. (Wikipedia)
Grounding & bonding requirements can vary between the CEC and NEC and local AHJ. Current code editions and local AHJs should be always be consulted. Proper grounding reduces the risk of shocks and fire and must be done correctly.
In a non-detached building, a contiguous and correctly sized ground conductor is required to any sub-panel. A sub-panel ground and neutral bus bar cannot EVER be interconnected. A detached garage may be considered part of the main house or building if it is physically connected by a breezeway (or similar).
For a sub-panel in a detached building, a ground conductor to it is not required but must have the neutral and ground interconnected in the sub-panel. A ground conductor can be run to the detached building but in that case it cannot have the neutral and ground interconnected. A ground electrode(s) is required in a detached bldg. in both cases. If there is a metallic pipe(s) between the main & detached building, you need to avoid multiple return ground paths.
Installing ground conductors correctly ensures that a fault (short) to ground in a feeder to a panel or downstream of a panel will trip the branch circuit breaker or feeder breaker (depending on where the fault is). Installing bonding conductors correctly minimizes the risk of different metallic items within reach being at different voltages. In Canada, there cannot be a ground conductor to a building housing livestock to avoid "tingle voltage" - not sure about the US.
Grounding for pedestals in an RV park has been the subject of debate and disagreement in the US for some time. The 2017 NEC will eliminate any further possible confusion and not require a ground electrode at a pedestal. IMO, a ground rod at each pedestal should be req'd considering how well (not) electrical systems are maintained in many CGs. As a side note, NFPA is also proposing that a new RV park must have 40 percent of pedestals with 50 amps, up from the current 20 percent.
