Residential Service Calculations

[@brandondenton494]

Excellent video brother !!! You helped me more than you know I’m now a sub and will be watching more of your videos

[@electrical1019]

Thank you very much! We are glad to help!

[@CIRIHawaiiLLC]

Great lessons. Question for Step 8. "If ac or heat was the largest motor and was NOT used in step 4, it is NOT counted." But we use the heater in step 4 so shouldnt 25% of the 8kv be added to the calculation? or am I misunderstanding that if the heating unit isnt presented with a HP value, its not considered a motor?

[@leonardopereira9806]

What size aluminum power conductor is needed for a 200 amp feeder in a two family home with a 400 amp service supplying both families? But with public service

[@electrical1019]

Are you referring to the service from the meter to each individual dwelling unit? If so, this would be sized based on table 310.12, so a 4/0 AWG conductor would be required.

[@CryptoiNNERG]

This information is very accurate. Surprised to hear Kentucky still uses 2017 NEC oppsosed to 2020. Just curious do you recall when Kentucky switched to 2017 & what year did they switch up to 2017 from?

[@electrical1019]

You may be surprised to know that as of now anyway, the majority of states (around 25) are still on the 2017, and only about 10 have adopted the 2020 edition. There are actually one or two states who are still on the 2008 code, and a few on the 2011/2014 code. Even worse there are a few who haven't adopted any edition, and just go by local codes. Kentucky switched from the 2014 code to the 2017 edition in 2018 if I remember correctly, and from what I've heard there hasn't been much discussion about adopting the 2020 as of yet.

[@runtaror57]

Thank you for that good explain. Did you use the NEC 2020?

[@electrical1019]

Hi there! Currently these videos are based on the 2017 NEC, since that is the current code edition adopted by the state of Kentucky. This means if you go to take a licensing exam for Kentucky, all of the questions will be based on the 2017 NEC as opposed to the 2020. Thank you for the positive feedback!

[@loopycreates_______9336]

Hi, I do have a question. Why would we not multiply the 28amp A/C unit by 125% giving us 35 amp X 240 giving us 8,400 which would be the higher of the two units?

[@electrical1019]

Hi there, I’m assuming your basis for the 125% rating is coming from section 440.32? If this is the case, 125% applies only to the branch circuit conductor rating, not the actual load of the equipment. The same applies also to 430.22. Hope that helps!

[@devontaedockery]

Awesome video. Thank you

[@electrical1019]

Thank you!

[@jakes.5591]

I don't understand how the furnace blower motor is coincidental with the A/C the blower is going to run whenever the AC is running. (If it's a typical gas furnace with evaporator coil mounted on top.)

[@electrical1019]

HI there, for the sake of this example and the way this type of question would be worded on a licensing exam, it's not specified if the heat/AC unit would be a furnace, heat pump, etc. The only information we know is that there is 8kW of heating (again, this could be an electric furnace, electric baseboard, etc.), and some type of AC unit that has a 5HP motor as its only load (as with the heat, the type of AC doesn't matter). For a real world application, obviously if a the heat and AC were the same source as with a heat pump unit or a furnace with an evaporator coil as you provided an example, you would only need to consider the total load of that unit at its maximum, which is usually plainly provided by the manufacturer. Hope that helps!

[@godman5043]

Top notch - thank you!

[@electrical1019]

Thank you very much!

[@mcarroll598]

What code book are you using.? Some of the tables aren’t there in the 2023 and 2020 code book that you are referring to in the video.

[@electrical1019]

These videos are based on the 2017 NEC. All of the tables in this video are in the 2020 and 2023 NEC, but their naming has changed. We also have videos covering the 2020 NEC!

[@mcarroll598]

@@electrical1019 ok thanks.

[@adrianesparza8473]

How do i get HP to Volt-Amperes?

[@electrical1019]

Hi there, the first thing you have to do is establish if the motor is single phase of polyphase (I am assuming you are asking about an AC motor). If the motor is a single phase, we would go to NEC table 430.248 and find the corresponding amperage listed for the motors voltage. We would then use ohms law to calculate the wattage, or VA. We would do the same thing for a polyphase motor, except we would use NEX table 430.250 instead of 430.248. I have a video on my channel that covers motor calculations in depth that I would highly recommend watching. Hope that helps!

[@infinite23eli]

Use article 310.12. It does the final step and sizes conductor.

[@electrical1019]

Hi Michael, this presentation is based on the 2017 NEC, in which they had removed table 310.12. If you are using an older code book that still has that table, or the 2020 NEC in which they added the table back, you are absolutely correct that table 310.12 should be used. Thank you!

[@holdurhorse9149]

What is markowave?

[@amilcar_coco]

You have any socials to contact you for help ?

[@electrical1019]

Hi, currently we don't, but we are more than happy to take/answer comments and questions on here! Thank you!

[@EvIScErAtED666]

Well with a refrigerator you have an ice maker with needs tools just sayn

[@FunSlime_]

ford ranger