Service Feeders and Branch Circuits - Section 8 Flashcards
What is a “demand factor”?
What is a demand?
Why do we use them?
A percentage of the total demand of an electrical feeder circuit determined from statistical data.
A base wattage value of the expected average load put on a feeder or branch circuit.
Because not all loads (or components within a load) will operate at once.
When determining living area, what percentage of the basement is counted?
75%
What is a basic load based on?
How is it calculated?
Living area.
Living area divided by 90 m2 rounded up, plus 4 - all multiplied by 1000 W.
How would a service load be calculated for an electric range?
6000 W plus 40% of any demand exceeding 12000 W.
How would a branch circuit load be calculated for an electric range?
8000 W plus 40% of any demand exceeding 12000 W.
If a range is not provided for, how should the miscellaneous loads of the house be calculated?
100% of the total sum of demand (only counting loads exceeding 1500 W) up to 6000 W plus 25% of the demand exceeding 6000 W.
Which loads of a single dwelling are taken at 100% demand?
- Air conditioning
- Electric tankless water heaters
- Electric water heaters for steaming
- Swimming pools
- Hot tubs
- Spas.
If a single dwelling has an 85 m2 main floor and a calculated load of 89 Amperes, what will be the minimum ampacity of it’s service conductors?
100 Amperes, because of 8-200(1(b))
How are loads 1500 W and under accounted for in service calculations?
With the basic load.
Bus bar ampacity should always be “_____” the ampacity of the service conductors.
Equal or greater than.
What is the minimum number of branch circuit positions required in a single dwelling? And a dwelling unit?
16, where at least half could be double pole breakers and with at least two left open for future use.
8.
Generally, could a dryer always be fed with #10 conductors and protected by a 30A breaker.
Yes, unless specified as hardwired.
What is the first thing to ask yourself, when performing an apartment service calculation?
What wire am I sizing?
This is because there are multiple different subrules, which size:
Dwelling unit feeders, Main service feeders and house panel feeders, respectively.
When dealing with automobile heater recepticles, which rule must be referenced?
8-400.
When calculating a demand for an apartmain main service feeder, what is the demand factor for which to take additional resistive loads?
They are taken at 75%.