ARE 346N Building Environmental Systems
Homework Assignment 6 March 26, 2009
DUE: April 7, 2009 60 points total
The objectives of this assignment are for you to demonstrate your ability to use the NEC as a
reference for electrical system design and design residential systems
.
1. Using the NEC (NFPA 70) 10 pts
Use the NEC (online version available through the library website, hard copy in the library and
in the architectural design lab) to answer the following questions. In which section did you
locate the answer? Be specific about what article, section, subsection, and paragraph you
found the answer (i.e. the grader should be able to find where you got your answer quickly).
a) Can you use a 6 AWG conductor for a professional arc or xenon movie projector?
b) What is the difference between Class I and Class II hazardous locations?
c) Do all circuits in health care facilities need to be grounded?
d) Do all receptacles in a bathroom need to have GFCI protection?
e) How many receptacles are required in a (residential) living room?
2. Sizing a residential system 20 pts
Using the procedure defined in NEC article 220-30 and discussed in class, design the electrical
system for a house in Austin. The goal of this assignment is for you to do the calculations as well
as gather some of the required data. You can not use default values for five of the appliances
and other electrical loads (excluding duplex outlets and lighting). You must document (with
photographs, photocopies of manufacturers literature, rubbings of nameplate, information from
manufacturers web sites, or measured power values (power meters are available) for at least five
of the loads in the house. This information should show the current (A) or power (W) that
the device uses, the voltage is not sufficient.
The house is a 1500 ft2 three story house in Austin with 4.5 tons of air conditioning (two units –
3 tons and 1.5 tons). It uses two natural gas furnaces for heating. The fans for the furnace/air
conditioner consume 900 W each. The house has the following electrical loads:
• electric dryer
• washing machine
• 50 gallon electric water heater
• garage door opener
• 3 ceiling fans
•electric oven (w/ natural gas stovetop)
• garbage disposal
• jacuzzi bathtub
• 15,000 gallon swimming pool (requires pump and heater)
Lighting (assume 3W/ft2) + 15 60W outdoor fixtures,
Duplex outlets (assume 20/floor + required appliance circuits in kitchen and other rooms)
Size the electrical system and select the panel size. Show all of your calculations.
