Electrical Acceptance Test Plan

[Calrissian45]

My employer has an electrical acceptance test plan that measures the voltages at the panelboard, transformer, and furthest outlet to verify that the voltage drops are within the maximum recommended 3% for branch circuits and 5% for branch and feeder circuits combined. I was tasked to update it and as I was looking it over I realized that the voltage drop is determined by the load and this test plan is measuring no load conditions, which seems kind of worthless. So I'm curious if anyone has any insight on what to test under no load conditions to verify that the electrical power system was installed correctly. We can't test under load conditions (without simulating the load) since the loads are installed by others after we leave the job site.

 

[charlie b]

Either find a way to connect a load that is representative of what the outlet will serve, or stop doing this test in its entirety. Even if you can simulate the load on any given outlet, the test is worthless. The voltage available at any specific outlet during normal facility operations will depend on the load being drawn by every other outlet throughout the facility. I doubt you will be able to accurately simulate that. That brings me back to this: never do this test again. :happysad:

 

[Calrissian45]

I decided to change it to a test for the nominal voltage to verify that the system is IAW ANSI C84.1. I think this is what was originally intended, but the document creator didn't think it through very well.

 

[brian john]

We have been hired to perform VD test for several projects, we have a variety of small resistive loads we use. Time-consuming but it pays the bills.

 

[JoeStillman]

We have been hired to perform VD test for several projects, we have a variety of small resistive loads we use. Time-consuming but it pays the bills.

I'm curious, have you ever done a test that didn't pass?

 

[Besoeker]

Either find a way to connect a load that is representative of what the outlet will serve, or stop doing this test in its entirety. Even if you can simulate the load on any given outlet, the test is worthless. The voltage available at any specific outlet during normal facility operations will depend on the load being drawn by every other outlet throughout the facility. I doubt you will be able to accurately simulate that. That brings me back to this: never do this test again. :happysad:

At least it would show if it was connected correctly. Probably.

 

[Coppersmith]

I decided to change it to a test for the nominal voltage to verify that the system is IAW ANSI C84.1. I think this is what was originally intended, but the document creator didn't think it through very well.

I don't know anything about the requirements of IAW ANSI C84.1. As far as the NEC is concerned, there is no requirement, just a suggestion. Voltage drop appears to be tested in a no load condition. Not sure about other building codes, but the Florida building code makes these voltage drop notes into requirements.

210.19 Informational Note No. 4: Conductors for branch circuits as
defined in Article 100, sized to prevent a voltage drop exceeding
3 percent at the farthest outlet of power, heating, and lighting
loads, or combinations of such loads, and where the maximum
total voltage drop on both feeders and branch circuits to the
farthest outlet does not exceed 5 percent, provide reasonable
efficiency of operation. See Informational Note No. 2 of
215.2(A)(1) for voltage drop on feeder conductors.

215.2 Informational Note No. 2: Conductors for feeders, as defined in
Article 100, sized to prevent a voltage drop exceeding 3 percent
at the farthest outlet of power, heating, and lighting loads, or
combinations of such loads, and where the maximum total voltage
drop on both feeders and branch circuits to the farthest
outlet does not exceed 5 percent, will provide reasonable efficiency
of operation.

 

[Calrissian45]

ANSI C84.1 sets a standard for acceptable nominal voltage ranges at the service panel and at the outlet. This can be tested under no load. We design our system to meet the NEC's recommended voltage drop, but since we don't actually install the load equipment, we can't easily verify that our system meets the voltage drop requirement. So verifying compliance with ANSI C84.1 is an acceptable alternative for our needs.

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[Ingenieur]

some questions are better off not asked
if the wire is sized properly for the load little chance of an issue
what if it fails the test? pull new wire?
you could put a jumper plug at the recept/load and measure loop R
v drop = max ckt amp x R, mOhm range meter

better off
meggering hot to gnd
hot to hot, open cb
isolated neut to gnd
continuity neut to gnd

but imo overkill

 

[petersonra]

I don't see how you can do any kind of load testing that is Meaningful. I'd be inclined to just test to make sure that the voltage with no load is acceptable throughout the entire building via a sampling of points. If you want to do voltage drop testing I think you would have to find a way to put a really serious set of loads on the system to make it meaningful.

 

[Santa49]

I don't see how you can do any kind of load testing that is Meaningful. I'd be inclined to just test to make sure that the voltage with no load is acceptable throughout the entire building via a sampling of points. If you want to do voltage drop testing I think you would have to find a way to put a really serious set of loads on the system to make it meaningful.

How does the Ideal 61-164 work for voltage drop testing?

 

[petersonra]

How does the Ideal 61-164 work for voltage drop testing?

It puts a relatively small load at one point. What good does that do?

 

[Ingenieur]

It puts a relatively small load at one point. What good does that do?

let's say you measure no load voltage at the load
say 120
then you put an R load and get 2 A and it drops to 119.5
wouldn't 20 A be 5 volt drop

v drop = 0.5 = 2 x R or R = 0.25 Ohm
v drop = 20 x 0.25 = 5 volt

should work anywhere as long as the R (or i) is known and v accurately measured it can be extrapolated

 

[Besoeker]

let's say you measure no load voltage at the load
say 120
then you put an R load and get 2 A and it drops to 119.5
wouldn't 20 A be 5 volt drop

v drop = 0.5 = 2 x R or R = 0.25 Ohm
v drop = 20 x 0.25 = 5 volt

should work anywhere as long as the R (or i) is known and v accurately measured it can be extrapolated

I don't disagree with any of that basic stuff but who carries around a 2A, 240W resistor?
What if you have to deal with 208V or 277V or 480V?

 

[Ingenieur]

I don't disagree with any of that basic stuff but who carries around a 2A, 240W resistor?
What if you have to deal with 208V or 277V or 480V?

if you're testing you need the equipment
I've done it with a 480/1 5 kw unit heater (5000/460 = 10.87 A, 460/10.87 ~ 42.3 Ohm)
we would actually measure R it before every use
trouble shooting not commissioning
I would never do it on every job
only when we thought we had a v drop issue
we switched it with a contactor and used recording vom
not an exact science