Varied Calculations Drill 2 ©Ted “Smitty” Smith 2008

Instructions This speed drill focuses on calculations that will be required for the journeyman and masters examination. The question slide will still transition in 3 ½ minutes and will be followed by the correct answer which will stay on the screen for only 10 seconds. Do not worry about writing down the correct answer during the transition. At the end of the questions, a stop slide will appear and then that will be followed by the questions and answers without the timer so you can review them. You must click on the screen icon in the lower right hand or left corner of the tool bar to start the slide show in order for the timer to operate.

Load Calculation What is the minimum demand on the main service entrance of a single family dwelling that measures 3600 square feet and is equipped with a 14.2 kw range at 240 volts, a 3.6 kw water heater at 240 volts, a 4.6 kw ari conditioning unit at 240 volts, a 1.2 kw dishwasher at 120 volts, a .95 kw garbage disposal at 120 volts, a 2.1 kw permanently installed trash compactor at 120 volts, and a 2.1 kw sump pump at 120 volts. The home is also equipped with 12 separately controlled baseboard heating units rated at 2.1 kw each at 240 volts. Copyright 2005 Ted "Smitty" Smith

Load Calculation 49292.5 VA

Fastened In Place Appliances A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. What is the fastened in place appliance load on the main service entrance of this dwelling? Copyright 2005 Ted "Smitty" Smith

Fastened Place Appliances 1100 garbage disposal 1200 dishwasher 4900 water heater 2100 instahot 2100 instahot Total= 13500 x .75= 10125.00 VA

Lighting Circuits A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. What is the minimum number of 15 ampere lighting circuits required for this dwelling unit? Copyright 2005 Ted "Smitty" Smith

Lighting Circuits 6300 x 3= 18900 VA 18900/ 120V= 157.50A A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. 6300 x 3= 18900 VA 18900/ 120V= 157.50A 157.50/15=10.5 11 circuits required Copyright 2005 Ted "Smitty" Smith

Load Calculation A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. Using the optional method, what is the minimum sized service required for this home? Copyright 2005 Ted "Smitty" Smith

Load Calculation A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. 6300 x 3= 18900 4 x 1500= 6000 1 x 1500= 1500 4600 6200 3200 4700 1200 4900 2100 x 3= 6300 Totals= 57500 -10000-= 47500 X .40=23000 + 10000= 33000 The largest is the 12 kw of Electric heat 33000 + 12000= 45000 / 240= 187.5 A Min service is 200A 220.82 Copyright 2005 Ted "Smitty" Smith

Load Calculation What is the demand on the main service entrance of 200 feet of track lighting operating at 120 volts.

Load Calculation 200 /2= 100 100x 150= 15000 VA 220.43(B)

Motor Calculation What is the maximum branch circuit- short circuit protection allowed for a 208V, three phase, squirrel cage motor with the following nameplate ratings: 20 hp, 51.6 A FLC, 1.15 Service Factor, and Design B The short circuit protection will be done with an inverse time circuit breaker.

Motor Calculation 150 ampere inverse time breaker.

Raceway Fill What is the minimum trade name size conduit that can be used for a 310 foot conduit run that will contain nine 10 AWG TW conductors, five 2 AWG RHW conductors with outer covering, and two 6 AWG RHH conductors that do not have an outer covering? The wires will be installed in an intermediate metal conduit.

Raceway Fill The total area of the conductors is 1.0934 and a 2” IMC at 40% fill will allow 1.452. 2”

Grounding A 480V three phase service is fed by four parallel runs of 250 kCMIL THHN conductors. An equally sized grounded conductor is run with each set of ungrounded conductors. The service is rated at 1000 amperes. A main bonding jumper conductor is installed between the grounded bus bar and the grounding electrode bus bar in the service. The bonding jumper is a bare copper 1/0 conductor. Is this an allowable installation? Copyright 2008 Ted "Smitty" Smith

Grounding No. Table 250.66 requires a minimum 2/0 AWG copper main bonding jumper in this application.

Box Fill A pvc junction box that is permanently stamped as having a volume of 110 is installed as an underground junction box. The box has 4 pvc conduits entering the box. One conduit entering the box contains nine 10 AWG THHN conductors and one 12 AWG THHN equipment grounding conductor all of which terminate in the box. Another conduit entering contains nine 10 AWG THWN-2 conductors and one 12 AWG THHN equipment grounding conductor all of which terminate in the box. Two of the conduits entering the box contain eight 6 AWG THWN conductors and one 12 AWG equipment grounding conductors. All of the 6 AWG conductors are pulled through the box without terminating and a coil of 12 inches is left in each conductor for future maintenance. The 12 AWG equipment grounding conductors terminate in the box. No devices are present in the box. Is this an allowable installation?

Box Fill No it is not. The volume of the box is 110. The conductors need a volume of 127.25

Branch Circuit Calculations A branch circuit has a load of 17.5 amperes. The load is expected to operate at periods of 4 hours or more continuously. The branch circuit conductors are installed in a raceway that contains a total of twelve current carrying conductors. The branch circuit conductors are 8 AWG THHN copper conductors and they are protected by a 60 ampere inverse time circuit breaker for overcurrent protection. Is this an allowable installation? Copyright 2005 Ted "Smitty" Smith

Branch Circuit Calculations Yes it is allowed. The derated and adjusted load is 43.75 amperes. An 8 AWG THHN has an ampacity of 55 amperes. Applying 110.14(C) requires we ensure that the original load of 17.5 x 1.25 for continuous duty is covered by an 8 AWG THHN in the 60 degree C column and it is. 240.4 and 240.4(B) allow the protection of the conductors to be done by the next higher standard size if all three conditions are met and this installation meets those conditions. So a 60 ampere overcurrent device is allowed. Copyright 2005 Ted "Smitty" Smith

Feeders and Branch Circuits A fixed multioutlet wiremold assembly, that is 25 feet in length, is installed in an office building with a 120V, 20A duplex receptacle installed 12 inches from the end and every two feet thereafter. The wiremold is fed with three 20 ampere branch circuits and the duplex receptacles are divided evenly between the three branch circuits. Is this an acceptable installation? The devices are expected to by used simultaneously. Copyright 2005 Ted "Smitty" Smith

Feeders and Branch Circuits 25 x 180=4500/120=37.50/20=1.87 220.14(H) Two circuits are required and this application has three circuits. Copyright 2005 Ted "Smitty" Smith

Stop This is the end of the presentation. You can now review the slides and answers without the timer. Click the slide to advance to the next slide

Load Calculation What is the minimum demand on the main service entrance of a single family dwelling that measures 3600 square feet and is equipped with a 14.2 kw range at 240 volts, a 3.6 kw water heater at 240 volts, a 4.6 kw ari conditioning unit at 240 volts, a 1.2 kw dishwasher at 120 volts, a .95 kw garbage disposal at 120 volts, a 2.1 kw permanently installed trash compactor at 120 volts, and a 2.1 kw sump pump at 120 volts. The home is also equipped with 12 separately controlled baseboard heating units rated at 2.1 kw each at 240 volts. Copyright 2005 Ted "Smitty" Smith

Load Calculation 49292.5 VA

Fastened In Place Appliances A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. What is the fastened in place appliance load on the main service entrance of this dwelling? Copyright 2005 Ted "Smitty" Smith

Fastened Place Appliances 1100 garbage disposal 1200 dishwasher 4900 water heater 2100 instahot 2100 instahot Total= 13500 x .75= 10125.00 VA

Lighting Circuits A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. What is the minimum number of 15 ampere lighting circuits required for this dwelling unit? Copyright 2005 Ted "Smitty" Smith

Lighting Circuits 6300 x 3= 18900 VA 18900/ 120V= 157.50A A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. 6300 x 3= 18900 VA 18900/ 120V= 157.50A 157.50/15=10.5 11 circuits required Copyright 2005 Ted "Smitty" Smith

Load Calculation A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. Using the optional method, what is the minimum sized service required for this home? Copyright 2005 Ted "Smitty" Smith

Load Calculation A single family dwelling is 6300 square feet. It is equipped with 4 small appliance branch circuits, a 4.6 kw wall mounted over at 240v, a 6.2 kw wall mounted oven at 240 volts, a 3.2 kw cook top at 240 v, a 4.7 kw dryer at 240 volts, a 1.1 kw garbage disposal at 120 volts, a 5.9 kw air conditioning unit, 12 kw electric furnace at 240 volts, a 1.2 kw dish washer at 120 volts, a 4.9 kw water heater at 240 volts and three electric insta-hot heaters at 2.1 kw at 120 volts. 6300 x 3= 18900 4 x 1500= 6000 1 x 1500= 1500 4600 6200 3200 4700 1200 4900 2100 x 3= 6300 Totals= 57500 -10000-= 47500 X .40=23000 + 10000= 33000 The largest is the 12 kw of Electric heat 33000 + 12000= 45000 / 240= 187.5 A Min service is 200A 220.82 Copyright 2005 Ted "Smitty" Smith

Load Calculation What is the demand on the main service entrance of 200 feet of track lighting operating at 120 volts.

Load Calculation 200 /2= 100 100x 150= 15000 VA 220.43(B)

Motor Calculation What is the maximum branch circuit- short circuit protection allowed for a 208V, three phase, squirrel cage motor with the following nameplate ratings: 20 hp, 51.6 A FLC, 1.15 Service Factor, and Design B The short circuit protection will be done with an inverse time circuit breaker.

Motor Calculation 150 ampere inverse time breaker.

Raceway Fill What is the minimum trade name size conduit that can be used for a 310 foot conduit run that will contain nine 10 AWG TW conductors, five 2 AWG RHW conductors with outer covering, and two 6 AWG RHH conductors that do not have an outer covering? The wires will be installed in an intermediate metal conduit.

Raceway Fill The total area of the conductors is 1.0934 and a 2” IMC at 40% fill will allow 1.452. 2”

Grounding A 480V three phase service is fed by four parallel runs of 250 kCMIL THHN conductors. An equally sized grounded conductor is run with each set of ungrounded conductors. The service is rated at 1000 amperes. A main bonding jumper conductor is installed between the grounded bus bar and the grounding electrode bus bar in the service. The bonding jumper is a bare copper 1/0 conductor. Is this an allowable installation? Copyright 2008 Ted "Smitty" Smith

Grounding No. Table 250.66 requires a minimum 2/0 AWG copper main bonding jumper in this application.

Box Fill A pvc junction box that is permanently stamped as having a volume of 110 is installed as an underground junction box. The box has 4 pvc conduits entering the box. One conduit entering the box contains nine 10 AWG THHN conductors and one 12 AWG THHN equipment grounding conductor all of which terminate in the box. Another conduit entering contains nine 10 AWG THWN-2 conductors and one 12 AWG THHN equipment grounding conductor all of which terminate in the box. Two of the conduits entering the box contain eight 6 AWG THWN conductors and one 12 AWG equipment grounding conductors. All of the 6 AWG conductors are pulled through the box without terminating and a coil of 12 inches is left in each conductor for future maintenance. The 12 AWG equipment grounding conductors terminate in the box. No devices are present in the box. Is this an allowable installation?

Box Fill No it is not. The volume of the box is 110. The conductors need a volume of 127.25

Branch Circuit Calculations A branch circuit has a load of 17.5 amperes. The load is expected to operate at periods of 4 hours or more continuously. The branch circuit conductors are installed in a raceway that contains a total of twelve current carrying conductors. The branch circuit conductors are 8 AWG THHN copper conductors and they are protected by a 60 ampere inverse time circuit breaker for overcurrent protection. Is this an allowable installation? Copyright 2005 Ted "Smitty" Smith

Branch Circuit Calculations Yes it is allowed. The derated and adjusted load is 43.75 amperes. An 8 AWG THHN has an ampacity of 55 amperes. Applying 110.14(C) requires we ensure that the original load of 17.5 x 1.25 for continuous duty is covered by an 8 AWG THHN in the 60 degree C column and it is. 240.4 and 240.4(B) allow the protection of the conductors to be done by the next higher standard size if all three conditions are met and this installation meets those conditions. So a 60 ampere overcurrent device is allowed. Copyright 2005 Ted "Smitty" Smith

Feeders and Branch Circuits A fixed multioutlet wiremold assembly, that is 25 feet in length, is installed in an office building with a 120V, 20A duplex receptacle installed 12 inches from the end and every two feet thereafter. The wiremold is fed with three 20 ampere branch circuits and the duplex receptacles are divided evenly between the three branch circuits. Is this an acceptable installation? The devices are expected to by used simultaneously. Copyright 2005 Ted "Smitty" Smith

Feeders and Branch Circuits 25 x 180=4500/120=37.50/20=1.87 220.14(H) Two circuits are required and this application has three circuits. Copyright 2005 Ted "Smitty" Smith

Stop This is the end of the presentation. You can now review the slides and answers without the timer. Click the slide to advance to the next slide