voltage drop at receptacle

Status
Not open for further replies.
George Stolz

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Re: voltage drop at receptacle

Originally posted by jimwalker:
With no load he would read the max available.Sort of like long test leads.Then apply load and would get a lower reading.Is this guy testing every outlet ? How many inspections does he get done in a day ,2 ?
Click to expand...
This reminds me of a similar situation. There was a nice older lady complaining that her smokes were intermittently chirping, waking her in the middle of the night. Not false alarm, but "low-battery" chirping. Couldn't find anything wrong, so I replaced the smoke (obviously, she'd already swapped batteries) and crossed my fingers. Two days later, same deal. After hours of thinking on it and a trip or two more, I started to think, maybe I've got some bizarre open neutral problem that is allowing the LED to light, but not enough juice for the smoke's function, draining the battery: Needless to say I was grasping at straws at that point.

So I attempted to do everything reasonable to open the neutral to that smoke. I plugged in a vacuum, rated 12 amps, cranked it up, and watched my meter. The voltage dropped, but not below...113V, if memory serves. I did notice (with my new incentive for poking around) that the voltage didn't drop as much on outlets closer in the circuit to the panel.

Is that voltage drop in action? Is that essentially what this inspector's meter does? And how much is that!?? :)
 
dereckbc

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: voltage drop at receptacle

First voltage drop is not enforceable under NEC adopted rules. Local may be able too, but enough on that .

As far as the safety issue is concerned, I am fairly sure he is using Sure Test meter. If that is the case, there is no danger in putting a 20-amp load on a 15-amp circuit. The load is not applied more than a few milliseconds at a time. The meter will then read out a percentage at both 15 and 20-amps. In addition it will also test the ground fault circuit and tell you the impedance by putting the same 20-amp load between phase and ground.

In my experience using the meter, the results can be very misleading, usually reads better than actual results. The reason is clear, the system as a whole is not fully loaded, so what you see is not accurate representation of real world results. You have to load the system, then have a clear branch circuit with no load at the maximum distance to get accurate results.

So IMHO if you go in with the meter, very little system load, and get 7% (8 volts of 120) voltage drop, you need to examine the circuit closely to determine why. Is it length or a problem?
 
L

ldbelec

Member
Re: voltage drop at receptacle

We have taken apart every outlet he tags as low including the outlets feeding them and have found no problems. Some that he has tagged have been in the middle of the circuit! Make sense of that! We have never found a loose connection or bad receptacle. In some cases the circuits are in the vicinity of the panel. I don't believe distance is the problem. I'm sure in some cases in does contribute to the "problem"
 
C

caj1962

Senior Member
Re: voltage drop at receptacle

We ahd inspector that tried that for a while. I got him to stop at least on my jobs by pointing what others have said about VD being a FPN. I then asked him when was the last time the unit was calibrated and had he been certified as an operator. I asked this to his boss. Never seen it again on jobs with my name on the permit.
 
J

jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: voltage drop at receptacle

Now Websparky come on you called me down for calling him an idiot but your calling him a nut ;)
I am not above calling a bad inspectors boss till it gets to the point that his boss tells him to leave Jim alone cause he does not want a phone call everytime that inspector screws up.It worked and they took him out of the field.
 
J

jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: voltage drop at receptacle

Yep,LOL :)
Better keep that inspector off of highrises,he might just slip over the edge ;)

[ December 17, 2004, 08:24 PM: Message edited by: jimwalker ]
 
I

iggy2

Senior Member
Location
NEw England
Re: voltage drop at receptacle

Be careful with the "unenforceable" talk... The Mass State building code has an energy conservation section ("energy code") which allows no more than 5% from service to utilization point. The Mass energy code is taken from some model code (BOCA maybe?) so the same requirement may be popping up in other locations which adopt the same model code.

The question is though that the energy code which is in the building code is not enforced by the "inspector of wires". The building code is enforced by the building official. In MA, the inspector of wires and the building official are two different things.

I like the post about taking the voltage reading at two points - I might use that one if it's OK with you Charlie B...
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Re: voltage drop at receptacle

Iggy, unless someone points out a local code (as in adopted formally) as you have, most conversations here are dealing with the NEC.

So as far as NEC conversation, there is no need to be concerned with being careful with the "unenforceable" talk. :roll:

Roger
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: voltage drop at receptacle

Originally posted by iggy2:
Be careful with the "unenforceable" talk... The Mass State building code has an energy conservation section ("energy code") which allows no more than 5% from service to utilization point.
Click to expand...
Iggy that only applies to Commercial space, the requirement does not extend to residential.

1307.3 Voltage Drop:
1307.3.1 Feeders: Feeder conductors shall be designed for a maximum voltage drop of 2% at the design load calculated in accordance with 2701.0.

1307.3.2 Branch Circuits: Branch circuit conductors shall be designed for a maximum voltage drop of 3% at the design load calculated in accordance with 2701.0.
Click to expand...
I also note it only requires the design to maintain less than 5%. It says nothing about actually achieving that. :)

[ December 18, 2004, 07:48 PM: Message edited by: iwire ]
 
Status
Not open for further replies.
Top