Horsebox fridge and water pump questions

[carthorse]

I have never used the fridge in our horsebox ,all I have done is put things in there with an ice pack but today I had a look at it. It is an electrolux and I think must be gas and 24 volt as there is a gas pipe and ignition switch and then on the side of the cabinet above it there is a pull out switch , if I pull it out a light comes on , on the switch. the wires go to the fridge and to a fuse box thing and then on to [ I think] the battery. Do you think when I pull this out it is on or do I need to do something else? I would only use it while driving so it doesn't take any power from the main battery.
I also want to put in a water pump to use to wash the horse off, I have an external pump from an old caravan which seems to work well but I haven't fitted a coil hose and spray on yet, my question is there is a submersable one in the lorry already , are they strong enough to work a spray as I could buy another one of them?

 

[Honeyb]

Don't know about the water pump, but with the fridge you will need to press an ignition switch somewhere as well as holding the switch - contact a caravan company or someone who uses a caravan. Unless your battery is old or a bit tired it won't take much energy from it, although ideally you should have two batteries on board with a split charge system. Once the main battery on the lorry is charged the system then puts charge into the secondary battery. The secondary battery is what runs all the living accessories. Make sure if you have a split charge unit fitted that it's someone who knows what they are doing. If fitted poorly it can cause some nasty problems.