WATTS THIS ABOUT MOTOR OHMS AND HOOKUPS?
On main club sites the electric hookup point is a BLUE connector of the same type as fitted to your motorhome. It is rated at 16 amps and will be a socket outlet. (BS EN 60309-2 ) The joining lead will have a male plug connector on the “input” end and a female socket connector on the “output” end to link the hookup point to the motorhome.
Many club sites provide a hookup supply limited to the 16 amp rating of the blue connectors. However many other sites use circuit breakers which limit you to less current and temporary sites are frequently much more limited. The Camping and Caravanning Club temporary sites at the NEC for example are limited to 6 amps. Try and exceed the limit of the circuit breaker at the hookup and your supply will be automatically switched off. In most cases after turning OFF the offending load the circuit breaker can be manually switched back ON again. In a few cases you may need to see out the warden!
Most mains appliances are marked in WATTS. This is the unit of POWER.
You also need to know that the effective AC voltage from the mains supply will be about 230 / 240 volts. Volts are the electrical unit of pressure otherwise known as Electro Motive Force (EMF).
If you divide the watts taken by a mains appliance by the voltage (240) the answer will be the AMPS taken.
AMPERES (AMPS) are the electrical unit of CURRENT, the stuff that flows invisibly down the wires and makes appliances work.
For example a domestic electric kettle is frequently rated at 2400 watts (2.4KW). Divide this by 240 and you have 10 amps.
A camping kettle is likely to be 800 watts and dividing this by 240 gives just under 3.4 amps.
Don’t be fooled by microwave ovens. A typical 800 watt microwave oven gives out 800 watts of heat into the food but can take typically 1200 watts from the incoming mains supply. That’s at least 5 amps
Toaster?, typically 1300 watts and 5 amps.
Got a coffee maker? That’s another 1000 watts or 4.2 amps.
The electric heating in your van can vary greatly between different vans. Some give the ability to select 1000, 2000 or 3000 watts of electric heating. That’s about 4.2A, 8.4A and 13A respectively.
Water heaters in the region of 800 to 1000 watts 3.5A – 4.2 amps.
The Laptop will take less than 1 amp as should the TV.
The Dometic Fridge 125 watts or 0.5 amp
But don’t forget that if you have been thrashing your 12 volt battery and you have a potent charger on board that for every 10 amps you put into the battery you will be taking about ¾ amp from the mains.
Watts = VOLTS X AMPS
AMPS = WATTS / VOLTS
OHMS this is the unit of electrical RESISTANCE. Without any resistance the AMPS would be unlimited and the circuit breakers would open with a BANG!
OHMS = VOLTS /AMPS. So for your 2400 watt domestic kettle which takes 10 amps = 240 /10 = 24 ohms.
This you can measure with your multi-meter set to OHMS range to confirm.
All this is derived from OHMS LAW.
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