Just
wanted to take a shot at sharing my understanding of RV electricity.
Some fundamental basics -
There are 2 kinds of devices - those
that 'CONDUCT' electricity and those that 'USE' electricity.
Solid state devices do both but will not be included in this discussion.
Conductors of electricity
wire/busbar/plugs - used to transport or carry electricity
breakers/fuses - circuit protective devices (protect circuits -
no
appliances or devices)
<>switches - used to break circuits
Users of electricity - types
of loads (resistance, inductance and capacitance):
resistance - wire, electric heaters, lights, toasters
capacitance - capacitors (not too relevant in RV world)
Users of electricity are
considered the 'LOAD'.
Circuit protective devices:
Circuit breakers and fuses basically protect circuits - not
devices or appliances
Your rig and other devices draw power - it is
'pulled' not 'pushed' from the utility company based on demand. It is important to understand that the
load will only draw what it
needs. Having more available DOES NOT mean it will be used.
In the case of hooking an 50 amp RV to a 30 amp service doesnt mean it
will
draw any more than the sum of the loads used.
Everything down stream from
the
source is considered the load for any
devices upstream. Downstream loads can be viewed as a 'black box'
to all upstream devices.
The conductors of
electricity to these loads should be sized according to the downstream
load. If you have a 20 amp load, size the conductors and switches
for this
load should be sized to carry at least 20 amps current.
Oversizing conductors (wires/plugs) does not hurt. However, the
circuit protective devices (breakers/fuses) should be sized to protect
circuit - mainly based on wire size.
In the case of an RV the whole RV is a 'LOAD' to the pedestal - like a
black box from
the plug. This entire RV
should be viewed as 1 load for the service. This load is
sub-divided by a distribution box usually
inside the trailer/5th wheel/MH. Each sub-circuit should be sized
according to the load it serves. Often the total of all the
circuits may exceed the main rating - this is where power management is
required.
RV's wired for 50 amp service:
If your rig is wired for 50 amp
service, it has 2 - 50 amp services and 240VAC available. It
technically does not have 100 amps - but 2 separate 50 amp
services.
You may be able to run an accumulated total of 100 amps of devices, but
nowhere will you have a 100 amp breaker or fusing.
If your rig is wired for 50 amp
service, it is likely the sum of the combination of
accessories/appliances will draw 100 amps (2 - 50 amp services).
Having an RV designed for 50 amp and hooking to 30 amp service may only
cause the breakers at the pedestal to trip if the
load exceeds the available service.
Adapters:
There are basically 2 types of adapters:
molded rubber - male on one side and
female on the other
dogbone adapter - a male connector
connected to a short piece of wire (perhaps 1 foot) which is connected
to
a female connector
Adapter ratings:
30 amp female --->20 amp male: Usually a molded type
male/female - accommodates a 30
amp plug in a household type receptacle
50 amp male --->30 amp female: Usually a dogbone type -
male/wire/female
30 amp female ---> 30 amp male: Usually a dogbone type -
female/wire/male
Adapters are usually available
from most RV dealers or Home Supplies -
Wal-mart, Lowes, Home Depot, etc.
