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calculations

  1. Bank & office calculations 220.14.K

    NEC Code Forum
    I am trying to find out if dedicated office loads need to be added to the calculations for a Bank or office. I know i am supposed to use the larger of 1 va/ sq ft V/S receptacle load at 180va per yoke per 220.14.K with the lighting load at 3.5 va / sq ft. what i am questioning if there are...
  2. Service Entrance Conductor Size

    General Electrical Discussion
    I have a question that I'm not really sure I know the correct answer to. If you have dwelling unit calculation that comes out to, say 195 amps, can you still use 4/O aluminum? In 230.42 it states that the conductor shall have an ampacity not less than the maximum load to be served, but in...
  3. Reference book or list for electrical formulas?

    General Electrical Discussion
    Hi there. So, as I mentioned in my intro, I’m in my second year of apprenticeship. I’ve accumulated a pretty convoluted list of formulas, which I try to keep track of in a small spiral notebook. Not just Ohm’s law (which I remember with the EIR and PIE acronyms anyway) but also three-phase...
  4. Formulas at workplace

    General Electrical Discussion
    My boss assigned me to gather most commonly used formulas and calculations at the workplace. What I started is that I gathered data from internet/books and paste it into a word file, later on, I'll take the prints. But the problem I am getting is that there are tons of...
  5. Question about the 220.55 Table.

    General Electrical Discussion
    I know there is a post about this table, but my question is a little different. Now correct me if I am wrong, but when using this table specifically for multiple appliances, you are suppose to add up the results together to get the total kW..no? For example: One 8kW and Two 6kW. 1 x 8 = 8 x 0.80...
  6. Minimum number of receptacles for commercial?

    NEC Code Forum
    So I am just out of school and I will be starting at an electrical company as an apprentice on Friday and I was doing some practice problems. One of them was the branch circuit and feeder calculations for both dwelling and commercial spaces. I know dwelling is easy to figure out how many outlets...
  7. voltage drop for rooftop units

    General Electrical Discussion
    I am bidding electrical for the installation of several RTU's they are 10 Ton units, MCA 50, MAX fuse or HACR breaker 60. Some of the RTU's are 200 to 360 feet from the service. At one point in time, VD was a FPN, and now its not even in there but im in the habit of calculating for it. I would...
  8. Heater amp draw on 3-phase

    General Electrical Discussion
    I'm trying to set up 3 electric heaters in a system plugged into 240V/3phase arranged in a delta. Each heater draws 30A. A diagram of what I want to build can be seen at: https://drive.google.com/file/d/0B1ph7lVxtvhaTV93NXhiRldINlk/view?usp=sharing Will the amp draw on each leg be 60A? I think...
  9. KVA vs. KW for motors

    General Electrical Discussion
    I was doing some research for a customer who is installing a hot tub and I just wanted to be sure we were not going to overload his existing electrical system. (I originally wanted to do a load calc which included a number for his existing AC unit.) I found this quote below from an old thread...
  10. Calculating TOTAL RESISTANCE...I'm stuck

    General Electrical Discussion
    Anybody here good with math and formulas? I have a problem I can't get past. What is the total resistance of this circuit? 1/R = 1/6.25 + 1/7.5 Also, can you list step by step on how you figured this out? Thanks a ton :thumbup:
  11. Sizing Portable Generator for Central Electric Heating

    General Electrical Discussion
    I have a potential customer who asked me to install a transfer switch for her. She already has a 5000 Watt generator and I told her she will not be able run her heat with that. (I don't know the exact size of her heat at this moment but, let's say there are two breakers for her heating unit, one...
  12. Grounded conductor load calculation help

    Linework
    Guys, I need some help. I'm going to take my unlimited test next week and I know there's a load calculation on transformers. He question is a transformer diagram, the voltage is 120/208 volt. There's a total of 4 transformers.1 is 3 phase 30 kw continuously lighting load and is connected to the...
  13. Service calculations help..

    Services and Service Equipment
    Hello all, hoping to get some input.... Looking at a new office build out. Space in inside existing building. Never had to do Service calculations before, trying to work my way through it. It will have to be submitted for plan review. Square foot of office space=3495 sgft. Existing is a 42...
  14. Range Branch Circuits#2

    Residential Electrical Forum
    Hi, I have a question about some calculations I have done but am having trouble understanding if they are correct. So, right to the meat of the problem. The question ask a cook top is 14kw and is connected to 240 volt, What is the demand load. So, this is how i solved for the problem please...
  15. potential load cal

    Residential Electrical Forum
    on one circuit of recepticals how do you measure the full potentail load, is it full load for the first receptical then half for the next then quarter for the rest?
  16. Potentiometer Problems

    General Electrical Discussion
    Hey I'm new to this website and have a few quick questions. I'm wiring a potentiometer into the circuitry for a heated snowboard boot I'm designing. I'm just curious how you calculate the maximum current and voltage you can run through it without frying it. I'm using 6 3.7V 1500mA lithium-Ion...
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