voltage drop

[enireh]

when figuring voltage drop for a residential service, what is the minimum one should allow? 3%?

 

[paulengr]

How are you going to figure it when the loads are so variable? 3% is kind of a general number used for any service but realistically it's site specific.

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[gar]

190706-2104 EDT

enireh:

I believe you mean maximum voltage drop, not minimum.

What is the purpose of your question? Is it will equipment fail? Or does it relate to something like light flicker? Or TV flicker? Or computers resetting? Or does it cause protective equipment or circuits to trip?

For resistive heating elements I probably don't care?

For tungsten light bulbs I may dislike a 2% change in voltage to the bulb.

For my DeWalt radial arm saw with a high inertia load, 12" carbide tip blade, 30% during startup is really too much when receptacle is 125 V unloaded, and I want to do several restarts within a minute or so. This will trip a 20 A breaker after 2 or 3 restarts.

I may not want my computer input to drop below 105 V. Allowed voltage change will depend upon what the starting nominal voltage is.

Your load, nominal source voltage, and other factors will determine your criteria.

.

 

[ActionDave]

There is no requirement to calculate voltage drop for a residence in the NEC and there is likely no need to worry about it. A standard load calc is all that's necessary.

 

[nickelec]

There is no requirement to calculate voltage drop for a residence in the NEC and there is likely no need to worry about it. A standard load calc is all that's necessary.

NYC amendments made voltage drop recommendation a code!

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[ptonsparky]

NYC amendments made voltage drop recommendation a code!

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At what load do you calculate it for a residence?

 

[nickelec]

At what load do you calculate it for a residence?

SECTION 210.19

Subsection 210.19(A)(1) – Add a new sentence at the end of the paragraph before the first Exception to read as follows:

Conductors of branch circuits shall be sized to allow for a maximum voltage drop of 3 percent at the last outlet supplying light, heat or power and the maximum voltage drop allowable for feeders and branch circuit combined shall not exceed 5 percent.

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[electrofelon]

when figuring voltage drop for a residential service, what is the minimum one should allow? 3%?

Generally for a typical residence, I will figure 60 amps for the calc and look for about 2% VD. Thats over 300 feet with 4/0 AL. Thus, I dont even really think about it unless its really long or there is an abnormally high load.