ECN Forum
Posted By: sparky The code that ate my brain - 04/16/02 12:31 AM
My calc's show a 5% VD on a 120v 20a circuit @ 75' , my ideal tester shows similar results. ALL the circuits I run when i wire a residence, save dedicated runs, are usually more than this length in total...

comments? suggestions? discussion? [Linked Image]

[Linked Image from eddhayes.com]
Posted By: Chris Rudolph Re: The code that ate my brain - 04/16/02 12:54 AM
Does this mean that all your 20 amp circuits with #12 wire are loaded to the full load of almost 20 amps,just shy of tripping the breaker?

Chris
Posted By: George Re: The code that ate my brain - 04/16/02 01:23 AM
16amps is the correct design load for a 20amp circuit.

20amps is a lot of continous power for a residence. At 10amps and 120v you can go 150 ft before a 5% voltage drop on the same circuit.

I like to run 50amp 240v to subpanels and then feed 20amp circuits from those. It solves the voltage drop problem.
Posted By: ElectricAL Re: The code that ate my brain - 04/16/02 03:26 AM
What does the PoCo deliver to the Bus in your area? Around the seven county Metro Area here I commonly measure 126 V to ground at the service disconnect.

With the standard set at 120, at what point do I start tracking 5% of which voltage?
Posted By: watthead Re: The code that ate my brain - 04/16/02 03:27 AM
I would think that this is why most of us routinely install more than the minimum number of circuits required by code, and increase the conductor size when we run into the occasional circuit that is expected to be heavily loaded. This method will not produce the lowest possible installed cost, but it does allow you to sleep better, at least untill you get the service call for the 59 cent switch that failed.
Posted By: BrianSparky Re: The code that ate my brain - 04/16/02 03:31 AM
Hey Sparky,
Is that sculpture by DeVries?
-Brian
Posted By: sparky Re: The code that ate my brain - 04/16/02 09:49 AM
Quote
16amps is the correct design load for a 20amp circuit.

agreed George....so we'd be looking for the 'dedicated' or maximum load. yet the ideal tester has a 15a & 20a setting. So to use the 15a setting on a 20a circuit would be close?

Quote
Does this mean that all your 20 amp circuits with #12 wire are loaded to the full load of almost 20 amps,just shy of tripping the breaker?
Chris, i suppose an arguement could be made for a non-continuos load?

Quote
What does the PoCo deliver to the Bus in your area?
Al, it's inconsistent, so another variable to deal with.

Quote
Is that sculpture by DeVries?
Briansparky, dunno..ripped it off google...
[Linked Image]
Posted By: Bill Addiss Re: The code that ate my brain - 04/16/02 11:52 AM
Sparky(s)

The Sculpture is a work by 'Edd Hayes'
You can see more at; http://www.eddhayes.com/

Some good stuff there.

Bill
Posted By: Bjarney Re: The code that ate my brain - 04/16/02 03:09 PM
Great picture, but one question...was his rod tested at the proper 100kV/foot level?
Posted By: Tom Re: The code that ate my brain - 04/17/02 12:17 AM
I have only seen one voltage drop problem in a residence & it was a double wide that had to have near 150 feet of 14-2 to the furthest outlet. When one of those 12 amp vacuum cleaners was plugged into it, it about choked, voltage fell to 85-90 volts.

The homeowner had hired me to find code violations so he could sue the home builder.I found a few, but couldn't help him with the voltage drop problem.
Posted By: sparky Re: The code that ate my brain - 04/17/02 01:01 AM
Tom, you introduce the 'non-continuous' factor with the Vac.

Q-If we are to calc VD for the load, or max load, where is this written?

As an observation...I have noticed the POCO's parameters for UG service's calc out almost exactly to 100, 150 or 200A

[This message has been edited by sparky (edited 04-16-2002).]
© ECN Electrical Forums