Newbie- confused about eletrical

Junior Burger
2012/08/03 15:25:21
I opened my food truck on July 4th at an area festival that had electrical hook ups, everything worked. Now I want to be able to run everything curbside. The problem is this, I do not understand all the watts, AMPs, and AH. I have a 4000 gen and a 7500 gen. Neither will run my truck completely. Here is what I have:
two steamers- 1200 watts each =2400 watts
electric 'oven'- 1500 watts
two warmers- 500 watts each = 1000 watts
fridge - (443/kw per hr? its a standard fridge)
Over head light and cash register.
I do not understand why the 7500 watt gen can't handle the load? I'm willing to do just about anything to get this thing running properly. Unfortunately, I also do not have anyone willing to work on the 'kitchen' part of my truck so I will have to figure this out. Any help is appreciated.
Double Chili Cheeseburger
Re:Newbie- confused about eletrical 2012/08/04 19:22:56
I learned when I was overseas, there is RED current and BLACK current.  This is why the wires are red & black.  You don't want to mix RED & BLACK current, as it will kill you.     ... I think there must be someone on the other end pouring the current JUICE down each line.    ... So if you are a cook and don't under stand how CURRENTS work, I suggest hiring a Bartender or Electrician.  May be BOTH!   ...  hahaha  ... ...
post edited by edwmax - 2012/08/04 20:37:49
Double Chili Cheeseburger
Re:Newbie- confused about eletrical 2012/08/04 20:23:45
OK  ... without the Frig, lights & cash reg, the warmers, oven, & steamers total 4900 watts.  
Adding an allowance for:
  • the Frig (120v X 6 amp (?)=720 watts)
  • overhead Light & counter circuit (cash reg); assume 3 each 15 amp circuits (3 X (120v X 12 amp=4320 watts)
   4900 watts + 4320 watts =9220 watts  ... this is way more than the 7500 watt gen set.   The calculated load needs to be less than 80% of the maximum load of the gen set or you risk tripping the gen breakers by over loading.    ... The good news is that you can use both your gen sets by dividing the loads for each.  But DO NOT cross connect the gen sets!   I suggest using the 7500 to power the steamer, oven, warmer & Frig  and the 4000 to power lights & cash reg.
Now some of these do not run all the time, but the you must assume they do (& will at some point) when calculating the output of the gen set.
The electrical rating you gave for the Frig is the estimated TOTAL power consumption for a year. A standard residential Frig draws 4 to 6 amps @ 120 v.  I assumed 6 amps, but you must check yours electrical tag.   The '443/kw per hr' is correctly wrote as 443 KWhr.   That's 1 kw for 443 hours; or 2 KW for 221.5 hrs; or 443 KW for 1 hr; ect
post edited by edwmax - 2012/08/04 20:44:23
Re:Newbie- confused about eletrical 2012/08/06 00:16:04
4320 watts to power some overhead fluorescent lights and a cash register?
Junior Burger
Re:Newbie- confused about eletrical 2012/08/06 08:29:36
Thank you for the information. I don't really want to run both generators. Space is a HUGE issue, I have a very small truck. And these generators are portable. So I am loading them in and out with each setup. I am looking at a commercial Onan 10000. I'll be honest, I have no idea how these generators are installed on the truck. (Keep in mind, this is the first food truck in our area). Scraping this truck and starting over is NOT an option, I have too much invested. 
I looked through the posts related to building trucks but was unable to find information regarding electrical. If you have direct links, I would be appreciative. Thank you.
Double Cheeseburger
Re:Newbie- confused about eletrical 2012/08/06 09:49:30
Can you convert the steam tables to gas?
Vic Cardenas
Re:Newbie- confused about eletrical 2012/08/06 10:02:01
I just finally switched everything over to propane. Running 12v for hood system, water pump and lights. My life is so much easier now that I've made the full conversion. I'm going to be selling my inverter and my generator.
I think the more you can switch over, the better. Even if it's a slow process. Running around, trying to make a ton of electricity, is a terrible way to do business. So much can go wrong.
Double Chili Cheeseburger
Re:Newbie- confused about eletrical 2012/08/06 12:56:01

4320 watts to power some overhead fluorescent lights and a cash register?

yea ... a bit much  ... but the OP didn't tell us how many convenience circuits existed or the wattage of the lights; So as noted in the calcs, I assumed 3 circuits @ 15 amp (12 amp max code steady run limit).  This would allow for other items to be plugged in too.   ... Anyway the post was a basic demonstration on how to do the elect load calculations.    
As already noted by other post, if the cooking equipment was changed to gas, then the 4000 watts gen set should be able to handle the lights, cash register, & Frig.
Junior Burger
Re:Newbie- confused about eletrical 2012/08/06 15:55:30
Thank you to those that are bearing with me. Here is some more information. 
The overhead (fluorescent) light is hardwired as well as the vent hood (not used). There are 5 outlets with two plugs each - 10 total. The Circuit box shows 5-15 AMP breakers (they never trip). I never plug more than one appliance into any outlet. 
When I used an online calculator to convert watts to AMPs, 9220 watts (120v) converted to 76 AMPs. Obviously, this truck is equipped with 72 AMPs.  
If I remove the oven (1500 watts) and one warmer (500 watts), I should be able to run everything (total of 7220 watts) on the larger generator? But I can't. 
I guess I will have to find an electrician to tell me if this thing was wired correctly?
Double Chili Cheeseburger
Re:Newbie- confused about eletrical 2012/08/06 17:44:53
What is the size of the main breaker and is it a double pole breaker?  I think this may be abt 30 or 40 amp double pole breaker.   Now a quick check would be to compare that to the gen set spec sheet & output.   If the gen set is equal or greater than the main panel breaker, then you should not have a problem.  If the gen set is less, then you have to remove some loads from the circuits.
I have an idea the truck is wire correctly (hopefully).   I think one of your problems might be you are starting every thing up at one the same time by flipping the main breaker.   ... You can't do that.   There is a problem with power surge.
As I already stated the calculated running current should be no more than 75% or 80% of the rated load of the gen set.   This is to account for electrical surge when appliances start up.  For the 7500 watt gen set (assuming that is the max. output), you should not running more than abt. 5600 watts.  You could draw more current, but not if appliances are turning themselves on & off.  You need this reserve for electrical surge.  And the closer you run the gen set at max. output, the more you will have to manually monitor & operate the unit (not good).
What is the brand and model number of your gen sets?  The specs can be looked up online.   A 7500 watt gen is rated abt 50 amps output.
post edited by edwmax - 2012/08/06 17:49:30
Dr of BBQ
Filet Mignon
Re:Newbie- confused about eletrical 2012/08/06 17:49:21
You need a pro electrician. And I would be surprised if it doesn't take a good pro 3 or 4 hours of going through the system to figure out whats what with your truck.
Think about a couple of issues: picking up one generator and putting it into your truck at least twice a day is going to get old very quickly. And all the time you spend fooling around with anything else takes time and energy away from food and service.
Build your generator into the side below the floor of the truck.Just like a motor home.
Or build or buy a small trailer to mount it on.
Change what you can to propane.
You need to concentrate on food sales and service.
Junior Burger
Re:Newbie- confused about eletrical 2012/12/21 01:46:50
quel1970 i build trucks and trilers in iowa please call 515-729-2995 for some help on your truck.