Just so ya know where I am there are mobile homes with 200 amp service and Electric furnace with 2 60amp 240v feeders, Yes thats 2 2pole sixties..... you think the AC spins a meter in the summer you ain't seen nothin till you get a bill from one of these!!
Many of the FEMA homes (16'x75' MH's) that was used as temporary housing for Katrina was put up for auction and a few found there way up here, they all were 200 amp all electric and the problem was no parks around here offered anything higher then a 100 amp service, the other problem is they are not insulated to the standards for trailers in our cold climent, most were either put back in auction to be sold down south or converted to gas.
But back on topic:
There are many things that could cause an un usually high utility bill, as mention even an old abandon hot tub circuit that was never fully removed from a panel, other things like post light feeds, leaking underground garage feeds.
one of the first things I ask the home owner is have you installed any new appliances like hot tub's or started using any portable electric heating appliances, the biggest one that surprises them are the over sold Amish fire place that is "As seen on TV" that are over sold to save money and they are shocked that most times it will cause a higher electric bill, they are nothing but a 1500 watt portable electric heater put in a nice fancy wood cabinet to look like a fire place, in our area you do not want to use electric for anything that uses allot of energy, as I have pointed out in other threads our POCO is one of the highest in the country for electric rates and they just got another 7% increase this January.
So I try to point out to my customers that using electric will cost you as we have many who move into this area from states with low electric rates, also I despise those portable electric heaters as I have said before they will find the weakest link in any electrical system and most of the time they will cause outlet failures because of warn and corroded contacts or loose connections like stab-ins, I tell them if you wish to continue using them please do not leave them running when sleeping or not at home for their safety sake, I ask them to let me install a separate circuit and use a high grade receptacle for them.
Heres a simple list of things to look for or ask of a customer when confronted by sudden high electric bills:
First of all is to ask to see the last 3 electric bills, and if possible ones from the last year at about the same time that would show comparable heating/cooling days to see if it is nothing more then a rate change or new added charges such as tax's, transportation, or handling charges, look at the KWH usage for comparable average temperatures for that month warmer or colder months can make a big difference in how much energy you might use, like here we have been experiencing a record warm December and January and looks like its going to continue for February and my utility bill has been reflecting this except for the rate increases.
1 look for heating appliances that are controlled by temperature that could be malfunctioning or that have multiple elements that could have an element failure that would cause longer run times of the good element.
Ask if there is any recently broken window or other things that could allow outside air to increase run times of the heating/cooling.
look for outdoor fixtures controlled by motion or photo cells that are now staying on, look for under ground feeds that might have failed or have improperly made splices that can be leaking current to earth.
look in garages for things plugged in that they have forgot about, once found that they opened the water bled off valve that went into a underground pipe so really didn't make much sound, what that didn't realize was the air compressor was running way more then normal.
Look for pipe heating tape that could have a bad thermostat or old and cracked insulation leaking current to ground or where the outer insulation cover was pulled off by a animal to make a nest.
Heres one that many don't look for, duct pipe for forced air heating fell apart in a crawl space causing the heating of the crawl space that has open vents to the outside.
Hot tubs, many fail safe to heat mode so if outside they wont freeze, many home owners don't know this and if located in an area not frequented by the home owner will not know it is running in heat mode after a power failure, hot tubs can really add to a electric bill if used allot, and are expensive to maintain thats allot of gallons of water to keep warm and without a good insulated cover can really add to the electric bill, around here most wind up putting them on Craig's list when they find out how much they added to the electric bill.
one piece of advise about mechanical electric meters, don't ever suspect one for over billing as they can't the only thing that happens to them is they slow down not speed up, I don't know how many times I have been asked to check the meter, it will only under charge.
Also look at the voltage with a good RMS meter as over voltage will cause resistance loads to use much more energy and a transformer with a couple shorted primary turns will cause over voltage but is a very rare problem to find just don't over look it, had this at a apartment complex with a 6 unit building, had about 268 volts between the hots and about 134 volts to the neutral from each hot, but even as low of an over voltage this is it can add extra wattage to the output of a electric heating appliance and over time can add up, wasn't called there for high utility bills but for lamps not lasting long, also over voltage will cause TVSS systems that use MOV's to start using more energy as they start to clamp more, this can add to an electric bill, also end of life surge strips or TVSS devices can start using energy so look at them by testing if they are pulling any current without any loads plugged in.
They are other things but my mind is starting to blank out on me so I will try to add them as I think of them or maybe someone else can add to this list.