Pre-test emergency questions, help is much appreciated!

[PowerMaster]

Hello good people! I'm getting ready to take a State test and need some clarity in a few areas. I did my best to express my thought process in writing, providing different solutions to a problem to narrow down the correct answer. I thank you very much in advance!

Question 1. 210.23 (B) and (C)
Does the 80% max load requirement rule for 15A, 20A, 30A circuits only apply to cord and plug connected equipment or all 15A, 20A, 30A circuits, including dwelling general lighting receptacles and lighting?
For example, can I put 30Amp non-continuous hardwired equipment on a 30Amp circuit?

Question 2. Number of branch circuits for general receptacle/lighting for dwellings
From my understanding only the T. 220.42(A) includes 125% for continuous lighting loads. Therefore all the other VA numbers like 200VA per ft for Show-Window and 1,200VA per sign circuit are required to be multiplied by 125% for feeder / service calculation when operated continuously.
For example an office sign demand load: 1,200VA x 1.25 = 1,500VA. Where 1,200VA is the neutral demand load; 1,500VA is the phase demand load.
Following this logic, dwelling general receptacle/lighting circuit number should be calculated similarly:
2400 sq ft x 3VA = 7200VA
7200VA x 1.25 = 9000VA (lights are turned on for more than 3 hours)
9000VA / 120V = 75A
75A / 15 = 5 (15A circuits)
or
15A circuit x 0.8 = 12A (80% max load on 15A circuit according to 210.23 (B))
12A x 120V = 1440VA per circuit
2400 sq ft x 3VA = 7200VA
7200VA / 1440VA = 5 (15A circuits)

Or the 3VA requirement already includes 125% for continuous operation, like dormitory 1.5VA T.220.42(A) even though NEC doesn’t specify? So the calculation would look like:

2400 sq ft x 3VA = 7200VA
7200VA / 120V = 60A
60A / 15 = 4 (15A circuits)

Question 3. Which option is the correct way to calculate dormitory general lighting number of circuits?
The 1.5VA per sq ft includes 125% for continuous load (T.220.42(A) Note)

Given: 1300 sq ft, use 15Amp circuit rating.

Option 1
15A x .8 = 12A limit per 210.23 (B)
12A x 120V = 1440VA per circuit
1300 x 1.5VA = 1950VA
1950VA / 1440VA = 1.35 or 2 circuits

Option 2
15A x 120V = 1800VA per circuit
1300 x 1.5VA = 1950VA
1950VA / 1800VA = 1.08 or 2 circuits

Question 4. How many hardwired baseboard heaters are permitted on a 30A circuit? Which option is the correct answer?

Given: 1000W / 240V = 4.16A for each heater.

Option 1
210.23 (C)
30A x .8 = 24A circuit limit
24A / 4.16A = 5.8 (5 heaters)

Option 2
30A / 4.16 = 7.2 (7 heaters)

Option 3
210.23 (C); 424.4(B)
30A x .8 = 24A circuit limit
24A / (4.16A x 125%) = 4.61 (4 heaters)

Option 4
424.4(B)
30A / (4.16A x 125%) = 5.8 (5 heaters)

Question 5.
Given 3 multifamily dwellings, single phase, 240V, with following demand loads: 260A, 510A, 820A.

Questions:
I. Each dwelling OCPD?
II. Each dwelling feeder size?
III. Each transformer size?
IV. Each transformer secondary size?

I attempted to answer the questions, even though I imagine the transformer secondary and dwelling feeder as the same wire, according to my diagram below, unless the diagram is wrong:

Question 6.
Based on the previous question 5, a transformer OCPDs and conductor sizes depend on actual dwelling demand load and not on the manufacturer’s transformer KVA rating. Is this correct?


Question 7. Dormitory calculations.
How to do dorm. calculation?
I. If a dorm. building matches dwelling unit definition, do I just calculate everything exactly the same way as a regular multifamily dwelling, applying same derates? Except instead of 3VA per sq ft I have to use 1.5VA per sq ft from T.22042(A)? If that’s the case are general-use receptacles included in 1.5VA per sq ft?
II. If a dorm. building doesn’t have let’s say a permanent provision for cooking, do I approach the calculation as a commercial space, multiplying receptacles by 180VA each and so on?


Question 8.
What is counter-mounted boiler? Is it part of cooking equipment and calculated using T.220.55 as a range?

Question 9.
Hazardous area Classification is provided by an engineer, then what is the point of articles and tables like T.514.3(B)(1) that also provides area classifications?

Question 10.
I heard someone teaching that demand factors in T.220.47 do not apply to office and bank (banks are office-type occupancies) outlets, based on article 220.14(J). Also article 220.47 only permits 220.14 (H) and (I) to apply derates from T.220.47. Office and bank outlets are added at 100% to feeder/service calculation. Is that a common practice? There is no official Oregon amendment to NEC about it.

Question 11.
How to choose a right type (not size) fuse for equipment like HVAC or different motors? Does installation manual usually specify it?

Question 12.
Is bell box with strain-relief ok as a receptacle cord drop or pendant box is the only solution?

Question 13.
During Mike Holt's online class I learned that fastened appliances like a gas furnace must be hardwired unless permitted by the manufacturer to be cord and plug connected or it might cause a fire. Lets say a gas furnace has SO cord and plug for connection to a generator during power outages. I don’t understand how it becomes a fire hazard if proper cable and plug are used...

Question 14.
T.240.4(G) permits Air-conditioning and refrigeration equipment to use 75°C column for 14, 12 and 10AWG. Does also it apply to heat pumps?

Question 15.
I’ve never personally done that, so just doublechecking. Can Romex or any other wire be used as a fixture wire like 14AWG on 20A circuit? According to 240.5(B)(2)(2) - branch circuit taps.

Question 16.
MC type wire vs AC. Also aluminum vs steel MC wires. What are the applications for each type, how do decide what wire I have to use?

 

[tom baker]

You would be better off to break this long post into posts with 2 or 3 questions. It’s hard to answer and go back.

 

[tom baker]

I can answer 13. Seein in article 400 uses not permitted

 

[PowerMaster]

I can answer 13. Seein in article 400 uses not permitted

Thank you for your reply. Yes, it is not permitted to use cord and plugs for equipment that is not labeled for that. Just curious how it caused fires though, probably cords or plugs were too small for the load...

 

[PowerMaster]

You would be better off to break this long post into posts with 2 or 3 questions. It’s hard to answer and go back.

I'm afraid it might get harder for people to navigate between multiple posts if I spilt questions, thank you for the suggestion, at least now it is all organized in one place, like a real test

LETS SEE WHO CAN PASS IT NOW! I dare everyone!

 

[don_resqcapt19]

I'm afraid it might get harder for people to navigate between multiple posts if I spilt questions, thank you for the suggestion, at least now it is all organized in one place, like a real test

LETS SEE WHO CAN PASS IT NOW! I dare everyone!

Very few are going to take the time to read all of that and post answers....I know I won't be

 

[PowerMaster]

Very few are going to take the time to read all of that and post answers....I know I won't be

I understand, it's life, and life is busy. Would you recommend me to try somewhere else, do you know a good place where someone would be willing to help me out? I will gladly pay to anyone who has the knowledge.