Electrical

Electrical Questions? Ask an Electrician Online.

Electrical

We recently had two air conditioning units installed at our

church. The Installers wanted the...
We recently had two air conditioning units installed at our church. The Installers wanted the electrician to run separate 40 amps lines for each unit. Although the electrician ran the two lines, he used 10/3 and 30 amps breakers. Each 4 ton air unit calls for 30 amps, but each of the 10/3 lines run about 190 feet, so will these units still need 40 amp breakers? Should the electrician have used 8/3 and 40 amp breakers due to the long run?
Show More
Show Less
10/25/2013
Category: Electrical
Satisfied Customers: 3,957
Experience: 31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License
Verified

Hello.....my name is XXXXX XXXXX I will be happy to assist you with your electrical question. My goal is to exceed your expectations on Just Answer!

1) The National Electrical Code recommends that the voltage drop be less than 3% over the distance of the run.

2) Using 190 feet with 10 AWG Stranded copper conductors at a 30 amp load with 240 volts results in a 13.7 voltage drop or a 5.7% which is not acceptable.

3) Using 190 feet with 8 AWG Stranded copper conductors at a 30 amp load with 240 volts results in a 8.6 voltage drop or a 3.6 % voltage drop which is also not acceptable.

4) Using 190 feet with 6 AWG Stranded copper conductors at a 30 amp load with 240 volts results in a 5.4 voltage drop or a 2.3% voltage drop which is acceptable.

5) Using 190 feet with 6 AWG Stranded copper conductors at a 40 amp load with 240 volts results in a 7.2 voltage drop or a 3% voltage drop which is acceptable.

6) The condensers will have a "Minimum Circuit Ampacity (MCA)" rating on the nameplate of the condenser which I assume is the 30 amp value.

Therefore, due to the length of the run being 190 feet, the branch circuit conductors need to be sized as 6 AWG Stranded copper using a 30 amp double pole circuit breaker in order to satisfy the National Electrical Code recommendation.

Remember, that a 30 amp breaker calls for a minimum of 10 AWG conductors, but since the run length is long (190 feet) you have more resistance per foot in a 10 AWG conductor versus a 6 AWG conductor. The thicker the conductor, the less resistance per foot, thus the less voltage drop in order to agree with the NEC 3% recommendation.

Hope this helps.........If you have any additional questions, let me know and I'll be glad to answer them for you.

Otherwise, don't forget to rate me before you log Off.

The next time you have an electrical question, you can also request for me at:http://www.justanswer.com/home-improvement/expert-your-electrician
..........Thanks..............Kevin!

Category: Electrical
Satisfied Customers: 3,957
Experience: 31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License
Verified

Thank you for the excellent service rating.............much appreciated!

If you have any additional questions, just let me know.

Take care and have a great weekend...............Thanks............Kevin!

Category: Electrical
Satisfied Customers: 3,957
3,957 Satisfied Customers
Experience: 31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License

Kevin is online now

A new question is answered every 9 seconds

• Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
• Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Mike

Master Electrician

1,426 satisfied customers

Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer

Jason

Service Technician

3,942 satisfied customers

Over 20 years of experience in all types of installations, troubleshooting, and repairs.

Mike G.

Master Electrician

7,826 satisfied customers

Proven Professional 48 years Experience

Kevin

3,957 satisfied customers

31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License

AssuredElectrical

Master Electrician

3,264 satisfied customers

electrifier

Master Electrician

1,458 satisfied customers

Electrical contractor and electrical inspector for over 24 years with phone and networking expertise

Rich

Master Electrician

1,115 satisfied customers

Over 35 years residential, commercial, industrial wiring, install, troubleshoot, service, maintain

< Previous | Next >

Related Electrical Questions
Need GOULD Circuit Breaker Panel size 14WX42H. 1983. Just
just panel should not need electrician I am electric engineer myself … read more
George Smith
324 satisfied customers
I checked all circuit breakers to see if any tripped. I
Hi, I checked all circuit breakers to see if any tripped. I reset all of them and checked voltage. They are all receiving power. So I changed the 2 outlets that went out on the side of one room. Still… read more
Kevin
3,957 satisfied customers
I have a problem with a circuit breaker tripping fairly
I have a problem with a circuit breaker tripping fairly regularly. I believe I have too many plugs on one circuit. How can I check to see if I have too many on one breaker. I have done a lot of wiring… read more
George Smith
324 satisfied customers
My microwave flips a circuit breaker when I turn it on. It's
my microwave flips a circuit breaker when I turn it on. It's in the same location, same outlet, same everything. The outlet works with other things, like vacuum, elec light. The microwave works perfec… read more
Kevin
3,957 satisfied customers
Circuit breaker blew switch. Switch is not resetting. Just
Circuit breaker blew switch. Switch is not resetting. Just kinda dangles there, with no tension to either side. How can I fix this?… read more
Sam I
Electrician
B.S.
474 satisfied customers
The circuit breaker hasn't popped but in living room non of
The circuit breaker hasn't popped but in living room non of the 4 outlets are working. Checked the 4 plugs for any signs of loose wires or spark marks. ? What's next? … read more
Kevin
3,957 satisfied customers
I want to remove a double circuit breaker from electrical
i want to remove a double circuit breaker from electrical panel … read more
Sam I
Electrician
B.S.
474 satisfied customers
Can a General Electric type THQL-GCI hot tub circuit breaker
can a General Electric type THQL-GCI hot tub circuit breaker be tested with an ohm meter. … read more
Kevin
3,957 satisfied customers
I have 2 dedicated circuits in my circuit breaker box that
I have 2 dedicated circuits in my circuit breaker box that are 240V, they each have 2 hot wires going to them. The circuit is terminated to an individual plug (L6-20R) for each circuit. The device I'm… read more
Kevin
3,957 satisfied customers
I have 415 amps worth of branch circuit breakers. what size
I have 415 amps worth of branch circuit breakers. what size service do i need for my house? is 200 sufficient … read more
Kevin
3,957 satisfied customers
I'm trying to move a circuit breaker box in a place I'd like
I'm trying to move a circuit breaker box in a place I'd like to put a bathroom. Knowing it isn't code to have one in a bathroom, is a junction box ok? … read more
Mike G.
Master Electrician
7,826 satisfied customers
How do I determine the correct size circuit breaker panel
How do I determine the correct size circuit breaker panel for an stand alone workshop. I don't suspect I would draw more than 20 amps at any given time, but do I need a box assumes everything is turne… read more
Mike G.
Master Electrician
7,826 satisfied customers
What is the function that makes a circuit breaker different
what is the function that makes a circuit breaker different from a switch so that it is able to break fault current … read more
Kevin
3,957 satisfied customers
Was wondering which circuit breaker I should look into
Hello, was wondering which circuit breaker I should look into replacing. As it stands my Dryer flips the circuit breaker for the upstairs bedrooms. Should I look into replacing the circuit breaker for… read more
Kevin
3,957 satisfied customers
My circuit breaker is tripped and will not reset. I've
My circuit breaker is tripped and will not reset. I've checked wiring to outlets looks okay. At the electrical panel there is no power to breaker itself. I check other breakers and the have power. Any… read more
Eddie
Home Improvement Contractor and Repairs
High School or GED
1,052 satisfied customers
Honda EU7000is has 30 amp line with circuit breaker with
Honda EU7000is has 30 amp line with circuit breaker with each line up to 22.6 amps. Questions is 32 amp draw too large and will trip circuit breaker and can circuit breaker be upgraded to 40 amp to al… read more
Sam I
Electrician
B.S.
474 satisfied customers
I've checked ALL circuit breaker with a voltage meter. They
I've checked ALL circuit breaker with a voltage meter. They are good, but I still don't have power in both bathrooms. Not in the outlets or ceiling lights. Can you help. … read more
Kevin
3,957 satisfied customers
The circuit breaker tripped controlling all the electricity
The circuit breaker tripped controlling all the electricity in my son's bedroom. This circuit also controls the recessed lighting in the dining room. The only way I can reset the circuit breaker is if… read more
Mike G.
Master Electrician