Hosen MH LED 60D, User Manual

Sizing the 

Circuit 

Breakers

Using the 

Spec Sticker

Using the

Watts/Volts Method

Considering the

Power Factor

2 A / 0.7 = 2.8571 A 

Using the

Volt Amps Method

360 VA / 120 V = 3 A 

Selecting the

Circuit Breaker

22 A * 1.25 = 27.5 A 

Calculating the total current drawn by the fixtures connected to a particular circuit 
is not complicated if the installer has the right information at hand and knows how
 to interpret it.

With the fixture's current draw information, the installer can calculate and select the 
right circuit breaker size (rating) to which they can connect a group of fixtures. 

Our fixtures come with a sticker that indicates the current they consume in a 
circuit at the specified voltage. This greatly simplifies calculating the total 
current drawn. 

For instance, if the sticker on the fixture indicates, "0.1 A @ 115 VAC, 60 Hz" and the 
installer is connecting 12 of them on the same 115 VAC circuit, to determine the total 
current required by the fixtures it would be enough to do this simple calculation: 
0.1 A x 12 = 1.2 A 

Some installers may prefer to determine the current drawn by the fixture by dividing 
its power consumption, indicated in watts (W), by the voltage (V) on the circuit. As 
an example, assuming that a certain fixture consumes 240 W and it is connected to 
a 120 VAC circuit, the current it draws would be: 
240W / 120 V

2A

The above method is accurate only with fixtures whose power factor (PF) is equal, 
or very close, to "1." Otherwise, the calculated current may be too low with respect 
to the actual current drawn by the fixture. 

In fact, as the PF decreases, the difference between the current calculated using 
the watts/volts method and the actual current increases. 

Therefore, for fixtures with a PF below "0.9," the installer must always consider the 
fixture's PF when using the watts figure to calculate the current it draws. 

For the above example, if the published fixture's PF were "0.7," the resulting drawn 
current would be as follows: 

This is approximately equal

)( to 2.86 A, 2.9 A, or even 3 A, depending on the 

installer's desire for accuracy. In other words, the actual current ended up being 
close to 50% higher than originally calculated. 

If the fixture's sticker indicates the power consumption in "volt amps" (VA), the 
calculation of the drawn current is simply the result of dividing the amount in VA by 
the voltage on the circuit (V). For a fixture with a consumption of 360 VA, the 
calculation would be as follows: 

Note that when the power consumption is in VA, the fixture's PF is never part of the 
current draw calculation. 

The National Electric Code (NEC) determines that circuit breakers should handle 
80% of their rated capacity for continuous loads (those being on for three or more 
hours) and 100% for intermittent loads. For safety reasons, We recommends 
assuming that all loads are continuous. 

After calculating the total current the fixtures connected to a particular circuit will 
draw, the installer must consider the 80% rule indicated above. For a total current 
of 22 A, the calculation is as follows: 

The installer should use a 30 A CB because the immediately lower CB rating, 25 A, 
would not be enough for this load. 

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