13- 14% Voltage Drop acceptable in new home MBR?

[tortuga]

What is considered to be an acceptable voltage drop in a far master bedroom?

I take the code voltage drop FPN as guidance but I think it can be achieved using a mean average voltage drop calculation.
However in tract homes this means you have much higher VD at the end of the run. What is a good maximum for far receptacles say the last in the chain?
I am in the process testing and repairing a new home that was repossessed then auctioned off.
It was wired with one 15A AFCI bedroom circuit. Here in Oregon AFCI is only required in bedrooms still so contractors use as few breakers as possible. Looking at the way the circuit was run around each bedroom, then around a bathroom supplying 2 vent fans several cans, 2 light bars, a hall way with a few cans, 2 outdoor GFCI's (another story) ...etc I would not be surprised if it was 200 - 275' in length of 14AWG wire.
Testing the 15A AFCI circuit with an Ideal Suretest reveals a 13 - 14 % voltage drop at a 12A load 120V at every receptacle in the master bedroom.

I checked for loose connections etc. All receptacles, devices had been removed in haste by former owner whom got foreclosed on and the wires cut short in the boxes, all the wires were pigtailed by us. VD gets lower and more normal the closer I get to the panel so I am eliminating the possibility of a bad splice.
I double checked the splices and they look good.


Doing a quick calculation:
15.0 Amps Rated ampacity.
2.9495 Ohms Resistance (Ohms per 1000 feet)
0.058 Ohms Reactance (Ohms per 1000 feet)
16.8 volts voltage drop at 14%
0.9 Power Factor
Gives me 261.21 Feet.
So my 14% drop would be expected for that much 14/2.

I am considering pulling a 12AWG to a place on the circuit where I can split it in two and putting the bedroom on its own 15A AFCI.
Over kill?
Thanks in advance!

 

[weressl]

What is considered to be an acceptable voltage drop in a far master bedroom?

I take the code voltage drop FPN as guidance but I think it can be achieved using a mean average voltage drop calculation.
However in tract homes this means you have much higher VD at the end of the run. What is a good maximum for far receptacles say the last in the chain?
I am in the process testing and repairing a new home that was repossessed then auctioned off.
It was wired with one 15A AFCI bedroom circuit. Here in Oregon AFCI is only required in bedrooms still so contractors use as few breakers as possible. Looking at the way the circuit was run around each bedroom, then around a bathroom supplying 2 vent fans several cans, 2 light bars, a hall way with a few cans, 2 outdoor GFCI's (another story) ...etc I would not be surprised if it was 200 - 275' in length of 14AWG wire.
Testing the 15A AFCI circuit with an Ideal Suretest reveals a 13 - 14 % voltage drop at a 12A load 120V at every receptacle in the master bedroom.

I checked for loose connections etc. All receptacles, devices had been removed in haste by former owner whom got foreclosed on and the wires cut short in the boxes, all the wires were pigtailed by us. VD gets lower and more normal the closer I get to the panel so I am eliminating the possibility of a bad splice.
I double checked the splices and they look good.


Doing a quick calculation:
15.0 Amps Rated ampacity.
2.9495 Ohms Resistance (Ohms per 1000 feet)
0.058 Ohms Reactance (Ohms per 1000 feet)
16.8 volts voltage drop at 14%
0.9 Power Factor
Gives me 261.21 Feet.
So my 14% drop would be expected for that much 14/2.

I am considering pulling a 12AWG to a place on the circuit where I can split it in two and putting the bedroom on its own 15A AFCI.
Over kill?
Thanks in advance!

Your voltage drop is about 21.6% for 15A @ 275'.

Electrical equipment is designed to operate within +/-10% of the nominal voltage. The utility is also allowed to deliver variable voltage, so playing the two against each other 3% distribution allowance has proven to be the optimum solution. Since it does not have anything to do with safety, the NEC will NOT make it a rule.

 

[bob]

21% VD is correct. You need to find a voltage drop program and do some figuring. If you are going to use 12 amp load you need to replace the #14 ckt with 2 ckts of #12's and split the load.You would still get about 5.5% VD.

 

[Hv&Lv]

Wouldn't NEMA C84.1 come into play as far as voltage minimums and maximums are concerned?

 

[wirenut1980]

Wouldn't NEMA C84.1 come into play as far as voltage minimums and maximums are concerned?

As far as on the load side of the meter, it could be used as more of a guideline,but not required. For utilities, if states adopt the standard as law, then the utility has to follow that.

 

[tortuga]

Thanks for the replies.

My main question is what load do you use when evaluating a general purpose branch circuit in a dwelling for recommended VD? The 5% total voltage drop usually is applied to a known load. Here we know the load as 3va per sq ft and thats it. A 12A load at the end of the run for the 15A circuit seems like what the sure test recommends.
I am not planning on installing a 12A load there I need a baseline to determine if the system is designed so equipment can operate according MFR specifications.

I was using the southwire voltage drop calculator:
http://www.southwire.com/ProductCatalog/CalculatorController

However I am solving for wire length 1 way since voltage drop is known. I guess that southwire calculator adds Reactance and Power Factor.

I have no Idea how much 14/2 was used to get to the Master bedroom. I was guessing 200'.
I want to see if the total length of circuit seemed correct to rule out bad splices.

(VD*CM/K*I)/2

(17.08V*4110/12.9*12)/2=326.51 Feet one way?

The Ideal suretest uses a 12A load as the test for determining voltage drop.
The voltage drop is 14%.
http://www.idealindustries.com/prodDetail.do?prodId=61-165
The NEC recommends 5% total. Mike has a voltage drop page here:
http://www.mikeholt.com/technical.php?id=technicalvoltagedrop
Which has a link to a pdf on the suretest.

I could justify the 12A by 220.12 3va per sqft. 480 SQFT of the home is served exclusively by that circuit, however it could be argued that a 12A load will never be at the end of the run. Yet if one was you would then be in violation of 110.3(B) since the equipment would operate at 105V or less than manufacturer specs.
Thanks

 

[petersonra]

This is a design consideration and not a code problem.

It is the direct result of bad code making primarily to benefit a manufacturer, as opposed to providing a safe installation.

JMNSHO.

 

[Dennis Alwon]

I am considering pulling a 12AWG to a place on the circuit where I can split it in two and putting the bedroom on its own 15A AFCI.
Over kill?
Thanks in advance!

I have pulled a #10 AWG for a very long homerun in a house. One way to minimize the distance is to hit the nearest box then split out of there twice in opposite directions rather than daisychain.

 

[weressl]

Wouldn't NEMA C84.1 come into play as far as voltage minimums and maximums are concerned?

You probably thinking of [FONT=Times-Roman+2][FONT=Times-Roman+2]ANSI C84.1-1989, American National Standard for Electric Power Systems and Equipment - Voltage Ratings (60 Hz). A NEMA Standard would be optional, but when they are elevated to be an ANSI Standard it gains nationwide acceptability and in some cases enforceability by becoming a State or Local Code. The above Standard certainly IS what Utilties are lawfuly obliged to live by in most places.
[/FONT][/FONT]

 

[glene77is]

I have pulled a #10 AWG for a very long homerun in a house. One way to minimize the distance is to hit the nearest box then split out of there twice in opposite directions rather than daisychain.

Dennis,
Terrible avatar (IMHO), :happyno:
but
very good idea on supplying a long-homerun circuit, :happyyes:
hitting it in the middle.

 

[John120/240]

Dennis,
Terrible avatar (IMHO),

Surely your kidding, Janis Joplin, John Lennon, Jim Morrison, Jimi Hendrix,

Frank Zappa, George Harrison Some of the greats that left to early.

 

[Chamuit]

Our second home had a similar sounding problem. The entire garage, laundry, front entry, two bedrooms, an entire bathroom and the exterior receptacles were on one circuit. I took a 14-3 (Pre AFCI) 2/3 divided the circuits three ways. You might do the same with this and take two 14-2's somewhere where you could divide the circuit up three ways. You would probably cure the VD problem as well.

We don't have to test circuits here like you do.

 

[Twoskinsoneman]

Our second home had a similar sounding problem. The entire garage, laundry, front entry, two bedrooms, an entire bathroom and the exterior receptacles were on one circuit.

Contractors either greedy, or forced to do unprofessional installs to bring dinner home.....
I will never buy another home unless I wire it myself.

 

[glene77is]

Surely your kidding, Janis Joplin, John Lennon, Jim Morrison, Jimi Hendrix,
Frank Zappa, George Harrison Some of the greats that left to early.

Well,
Dennis is OK, and had a great suggestion.

So,
I admit I gave Standing Applause to Stevie Ray Vaughn !!! :happyyes:

IMHO, SRV was a far better guitarist than Jimi, but not as charasmatic,
His untimely early death cut his possibilties really short.
I really enjoyed that time.

So, Are we going for a 5% VD as Acceptable ???

 

[glene77is]

Contractors either greedy, or forced to do unprofessional installs to bring dinner home.....
I will never buy another home unless I wire it myself.

My sympathy ! :slaphead:

This house was like that.
I have spent lots of time adding circuits, chasing down crossed neutral/hot,
and still need to replace the FedPac load center. :rant:

 

[kwired]

My sympathy ! :slaphead:

This house was like that.
I have spent lots of time adding circuits, chasing down crossed neutral/hot,
and still need to replace the FedPac load center. :rant:

That is about the only advantage that is proven about use of AFCI, those kinds of mistakes will cause problems that are noticeable - usually immediately.

 

[Twoskinsoneman]

That is about the only advantage that is proven about use of AFCI, those kinds of mistakes will cause problems that are noticeable - usually immediately.

that IS one good thing. I wonder how many homes have been wired with accidental EGC to ungrounded conductor connections at a receptacle or two. Maybe EGCs should be required to be insulated?