Voltage Drop

Originally Posted By: jpope
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I know many of you may consider this ?beyond our scope,? but here goes anyway.


I?ve been performing quite a few ?new construction? and ?warranty? inspection as of late.

NEC Article 210-19 recommends the maximum drop at branch circuits to be 3% for reasonable efficiency.

In many of the homes I?ve inspected, the receptacles farthest from the service panel show a significant drop. I had one today that showed a drop of 10.9% at a 12 amp draw. No other power was in use as the home was vacant.

Is there any remedy that the homeowner can expect when this condition is reported? Is there any other requirement that can help enforce this recommendation?




--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

Originally Posted By: Greg Fretwell
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It probably is beyond your scope but you could use that tester to walk back to the panel and figure out where the problem was. I would bet you a cup of coffee and a cannoli it is a backstabbed device. Leave that 12a load on there for a while and that ~100w bad connection will show itself


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Originally Posted By: jpope
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What could my recommendation to the builder be in this case? Change over the receptacle connections to the screws?



Jeff Pope


JPI Home Inspection Service


“At JPI, we’ll help you look better”


(661) 212-0738

Originally Posted By: pdickerson
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Jeff,


A 10.9% drop at a 12 amp draw calculates to 150 feet of 14 AWG or 240 feet of 12 AWG copper wire. If these distances seem reasonable given the layout of the home, than the excessive drop may be from bad design (the electrician should have oversized the wires). If it is unlikely that there is 150' or 240' of cable between the recep and the panel, than I would guess Greg is right. Hope the smoke alarms are working.


Originally Posted By: bking
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Jeff, where were you measuring the source voltage at? Before the main breaker or at the branch wire ?


When I built a new house with 400a service and 2ea. 200 amp GE panels I noticed a slightly warmer area at the top of one panel with not much load present at that time and thought, what the *&%@ !

I wired these panels and know for sure everything I did was torqued properly. It looked like a 200a breaker was producing the heat but I did some more checking and ended up tightening the factory nuts on the bus bars just below the main breaker. Problem gone. One was fairly loose from the factory! Enough to cause voltage drop and heat with about 10-15 amps current. Learned to never trust anyones torquing, even the factory.


Originally Posted By: tallen
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Sometimes I wish I had never bought the Suretest.


I have found voltage drop in excess of 15 volts. However, every single time, there were so many other electrical problems that I called for a Sparky evaluation anyway.

I am not sure what I would do if I only found it on one recep.


It is beyond my scope, but if I push that button and find it. What should I do??

Do I risk the liability or do I blow it of???


What do you think I do?


--
I have put the past behind me,
where , however, it now sits, making rude remarks.

www.whiteglovehomeinspections.net

30 Oct 2003-- 29 Nov2005

Originally Posted By: bking
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I have a report addendum that list examples (but not limited to) of disclaimed items, one of those is “proper torque on electrical connections”


Originally Posted By: sramos
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Steven Ramos


EnviroVue Home Inspection


866-541-2883

Originally Posted By: phinsperger
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Jeff,


I have also found a VD of 9-10% in a vacant new home and as Greg mentioned, it turned out that the source was backstabbing.


--
.


Paul Hinsperger
Hinsperger Inspection Services
Chairman - NACHI Awards Committee
Place your Award Nominations
here !

Originally Posted By: Kyle Kubs
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When I first got my suretest I decided to see what the common voltage drops that I encountered where going to be on a dozen houses or more before I opened my mouth. I encounter 7-12% on a regular basis, new and old homes. It may be beyond the scope of what NACHI, ASHI, or anyone else might require as a minimum, but that does not mean we can’t make a decision that it is important and include it in our inspections. No one “requires” that I check for current in the conductor going to the ground rod/water pipe, but I put my amp meter on every one I inspect…


As far as reporting voltage drop... I call it out if it is excessive (above 15%) - Had one once that was 27%... This can be caused by many things... A few have been mentioned already, backwired outlets, plain old cheap outlets like the kind you get at the garbage depot for $1.19, excessive circuit length. Also look for where the Electricians helper was striping the insulation and badly nicked the wires, effectively reducing their gauge and their current carrying capacity, and things we can't see like broken wires, wires with nails through them, broken outlets... On new construction not all will apply and very often it is as has been said, backwired outlets, but even worse... when the circuit continues to the next outlet through the first (wired in series). Power in, and out backwired... ( I call it speedwiring) something no self respecting electrician will do... Outlets should always be wired from a pigtail so the current going to the remainder of the circuit isn't going through the outlet. (wired in parallel)

Jeff to get off a rant and answer your question - Until the NEC makes it more than a recommendation... I don't believe there is any hard and fast rule about voltage drop - Due to the potential for possible harm when it is excessive I always report it above 15%

Kyle Kubs
Benchmark Home Inspection Services
North NJ


--
Those that say it cannot be done should stop interupting those of us who are hard at work, doing it...

Originally Posted By: jpope
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Quote:
A 10.9% drop at a 12 amp draw calculates to 150 feet of 14 AWG


That seems about right.

Quote:
the excessive drop may be from bad design (the electrician should have oversized the wires).


This is exactly my point. I don't check this on older homes, but I would expect better from new construction.

Quote:
Jeff, where were you measuring the source voltage at? Before the main breaker or at the branch wire?


I check the drop at branch circuits where the recommended drop is a maximum of 3% by the NEC.


--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

Originally Posted By: jpope
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Quote:
Voltage drop measurements were taken at several interior receptacles. Many showed a significant voltage drop. Tests were taken under a 12 amp load showing a drop of up to 10.9%. The NEC recommends 5% as the maximum voltage drop at the feeders and 3% at branch circuits for reasonable efficiency (NEC article 210-19).

A common cause of excessive voltage drop is a loose connection within the circuit. "Back-stabbed" devices such as receptacles are a major contributor to voltage drops as these pressure connections may not allow for proper current flow. Connecting the conductors to the side screws may eliminate the excessive voltage drop. Breaker and receptacle connections should also be checked for proper torque.

Further evaluation by a state-licensed electrical contractor is advised for corrections.


It's a work in progress, so let's hear it.

I am out the door so I'll check back this evening.


--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

Originally Posted By: mboyett
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bking wrote:
Jeff, where were you measuring the source voltage at? Before the main breaker or at the branch wire ?


Bruce, I know what you are getting at. While I don't own or use a Suretest I did read the operating manual. It actually runs thru numerous tests when it is inserted in a receptacle. One of the 1st is to measure no-load voltage at that particular receptacle then it does the other tests including the 12 amp load voltage drop test. It displays voltage drop based on the no-load -vs- 12 amp load at that receptacle. So, having a low voltage condition farther back up stream should not cause a high voltage drop % reading at a receptacle. The Suretest would, however, probably indicate a low source voltage if that were the case.


--
Mike Boyett
Capital City Inspections
Austin, Tx
www.capcityinspections.com

Originally Posted By: roconnor
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This is a pretty sticky topic for home inspectors, so be very careful here.


The 3% to 5% VD is only intended as a guide for the "design" of the circuit for performance, which is not a safety issue. Actual VD in an installed circuit will vary. In addition, VD varies with the circuit load, and there is no standard for that. This is partially why VD is not a direct NEC code provision. Many say that those FPN's in the NEC should be removed because of mis-application, lack of standards (e.g. what current is to be used), and because performance is not a safety issue. However, a very high VD may be an indication of a high resistance circuit with a problem.

Be very very careful with reporting such detailed information about circuits that are only spot checked. What about the ones you didn't check, are inaccessible, or are hard wired which does not permit an easy plug-in check? Reporting that level of detail at least gives the appearance to a prospective homeowner that you are testing the entire electrical system ... when the truth is far from that in reality. Any testing/measurements can be a doubled edge sword, but the additional information can be useful as long as it's not misrepresented by the inspector or misconstrued by the client. The latter being pretty scary for an HI.

Just my opinion and 2-nickels ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jpope
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Point taken Robert.


I am fine tuning several aspects of my "new construction" and "builders warranty" inspections and reporting. That is the reason for any code references. Not as enforcement, but rather, as reason for the recommendation.

As a side note. I have not measured drops over 3% in any of the custom builds I've inspected. This only seems to be prevalent in multi-structure developments.

Obviously, a home built in 1940 may have many more significant reasons for excessive VD and the current NEC standards won't apply to the majority of the system.


--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

Originally Posted By: roconnor
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jpope wrote:
Voltage drop measurements were taken at several interior receptacles. Many showed a significant voltage drop. Tests were taken under a 12 amp load showing a drop of up to 10.9%. The NEC recommends 5% as the maximum voltage drop at the feeders and 3% at branch circuits for reasonable efficiency (NEC article 210-19).

A common cause of excessive voltage drop is a loose connection within the circuit. "Back-stabbed" devices such as receptacles are a major contributor to voltage drops as these pressure connections may not allow for proper current flow. Connecting the conductors to the side screws may eliminate the excessive voltage drop. Breaker and receptacle connections should also be checked for proper torque.

Further evaluation by a state-licensed electrical contractor is advised for corrections.

My thoughts on the suggested wording are:

1. Do not refer to measurements as "tests"
2. Do not reference the NEC or quote model code sections (even phased/warranty inspections)
3. Do not report hard measurement numbers in the report
4. Do not suggest possible solutions to a problem (e.g. connections)
5. Add wording when outside the standard HI scope or SOP

I would just refer to any circuits with high VD readings (whatever "guide" on installed circuits may be applied) as a "concern" to be further evaluated by a licensed electrical professional. If pushed on why you reported something as a concern, you have the readings and references to back that up, but leave the rest up to an electrical professional to take their own measurements and evaluate the installation. A possible alternate to that may be something along the lines of ...

Quote:
Although beyond the scope of the inspection, it was noticed that (___) was observed to have a apparently high drop in voltage under load, which may be a problem based on current construction guidelines. This is a concern as a potential wiring problem (nicked wires, loose connections, back-stabbed devices, undersized wires, etc.) and possible fire hazard. This may be a problem with the individual circuit or a more widespread problem with other circuits that are not checked as part of the inspection. All outlets and wiring were not checked for this potential problem, and a further evaluation and possible repair by a licensed electrician is (highly) recommended

And be crystal clear about there being no definitive standards, only spot checking outlets, not having access to all receptacles, not checking all receptacles, no check of hard wired circuits, and not being a system performance check. Sounds pretty sticky to me for an HI.

Just my opinion and 2-nickels ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: roconnor
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jpope wrote:
I am fine tuning several aspects of my "new construction" and "builders warranty" inspections and reporting. That is the reason for any code references. Not as enforcement, but rather, as reason for the recommendation.

Even as a basis for a recommendation or a phased construction issue, quoting a defect flag as anything other than being based on "current industry/construction/safety standards" can be very dangerous for an HI.

What is the legally adopted code in that area at the time of construction, is that a requirement or a recommendation, are you sure those sections really apply, and what is the legally authorized AHJ interpretation on those locally adopted applicable sections or revisions (per NEC 90.4). IMHO just dont go there.

Just my opinion and 2-nickels ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: kmcmahon
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If I even mention the word “code” in a new home construction inspection, I could get into big trouble. With the new Uniform Dwelling code inspections required in this state, you need a special license.



Wisconsin Home Inspection, ABC Home Inspection LLC


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Originally Posted By: jtedesco
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Make sure your home is wired for safety


More than 35,000 fires occur each year due to shoddy home wiring
NORTHBROOK, Ill.; Spring 2004 - The lights flicker when the central air is switched on. An extension cord in the bedroom outlet sparks. The power goes out every time the clothes dryer starts to spin. These are just a few telltale signs that the wiring in your house may need an upgrade. But experts say too often these signs go unnoticed or ignored, until it is too late.

According to the National Fire Protection Association (NFPA), there are more than 35,000 fires and 300 deaths every year due to shoddy home wiring. This might involve circuit breakers, switches, receptacles, outlets, cords, plugs and light fixtures. As owners and prospective buyers prepare for fix-up projects and house hunting, Underwriters Laboratories Inc. (UL) warns consumers to stay on the lookout for potential hazards that could signal it is time to upgrade your home wiring capacity.

"The reality is that we keep bringing more and more electrical products into our homes. But if a home is more than 30 years old, the home wiring system may not be designed to handle the combined amount of electricity that today's products and appliances demand," said John Drengenberg, UL's manager of Consumer Affairs. "We all need to be aware of warning signs that seem commonplace, but could indicate a potentially serious safety hazard."

Drengenberg said that some older homes could still be wired with 30 amp or 60 amp service, which normally is enough to power basic lighting and small appliances. Now, he said because homeowners typically want all of those small appliances, as well as larger electrical appliances, such as water heaters, ranges, clothes dryers and central air, they may find more capacity might be required.

A national survey by the American Society of Home Inspectors (ASHI) found that improper electrical wiring is the second most common problem they find when doing home inspections. Common defects include insufficient capacity, inadequate overload protection and amateur, do-it-yourselfer-type wiring or wiring connections in kitchens, bathrooms, basements and garages.

"Most home owners have the best intentions, but they are not familiar with the codes and the potential safety hazards that are common in do-it-yourself electrical work," said Stephen Gladstone, president of ASHI.

Drengenberg recommends homeowners and potential buyers pay attention to the following warning signs and realize that they may need to talk with a licensed/qualified electrician or consult a home inspector:

Anytime you are shocked in your home: A properly wired and grounded electrical system will protect you from most potential shocks.
Overloaded outlets: Too many appliances plugged into a single outlet could indicate your house may not have the required number of outlets. The National Electrical Code requires that outlets be spaced every 12 feet of running wall space, or one on each wall of the average 10-foot by 12-foot room. Kitchens typically require outlets spaced every four feet along the countertop.
Flickering or dimming lights: This could indicate loose connections, overloaded circuits, improper wiring, or arcing and sparking inside the walls.
Hot, discolored receptacles, switch plates, cords or plugs: If you can't keep your hand on these for more than five seconds, you may have an overload or product malfunction.
TV screen or computer monitor shrinks or wavers when a large appliance is turned on: This could mean you have too many appliances plugged into one circuit, or that your house needs additional electrical capacity.
Unusual smells: Burning metal or plastic smells may indicate a loose connection, malfunctioning switch, light fixture, broken connection, overheating components, arcing or sparking inside the walls, damaged wire, or other potential hazards.
Wobbly plugs: This could indicate that the outlet is outdated and worn. It should not be used and be replaced immediately.
No three-pronged outlets: In new housing the National Electrical Code requires three-pronged outlets everywhere on your property, including outdoors. If your house has none, then your system is likely outdated.
Blown fuses and tripped circuit breakers: Replace fuses and reset breakers. If it happens again, a problem exists somewhere.
Reliance on extension cords: Extension cords are meant for temporary use only. Any long-term products plugged into extension cords indicate your house does not comply with current National Electrical Code requirements.
Gladstone also suggests that consumers make sure any handymen or contractors they hire are qualified to do the work. If the work is electrical in nature, make sure to hire a licensed electrician and ensure that all applications for licenses and permits, which will require a third party inspection, are completed before work begins.

Quote:
"Home inspectors will look for evidence of potential hazards by making sure the house meets basic safety requirements and will identify poor workmanship," he said. "Municipal inspectors will make sure that all electrical installations meet the requirements of the National Electrical Code. Both inspections will keep your family safe."


Underwriters Laboratories Inc. (UL) is an independent, not-for-profit product safety certification organization that has been testing products and writing Standards for Safety for more than 109 years. UL tests more than 18,000 types of products annually, and more than 19 billion UL Marks appear on products each year. Worldwide, UL's family of companies and its network of service providers include 60 laboratories, and testing and certification facilities.

NOTE TO EDITORS: Interviews with a UL safety expert are available upon request. Please contact UL's Media Relations Group at +1-847-664-1508 or E-mail Joseph.F.Hirschmugl@us.ul.com.


--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: bbadger
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Jeff I think Robert OConnor has given some good advice here.


I must say as an electrician I have it easer than you do as an HI with this issue Not because of our different training but because of the lack of NEC direction on this issue.

Absent job specifications I have no standard I must meet, I can run 1000' of 14/2 and load it to 15 amps resulting in 27 volts at the load (93 volts or 77% VD) this would still be NEC complaint and if all code rules are followed, connections tight is not a safety hazard.

The person using the circuit would not be impressed.

The other side of the coin I get a job specification that requires VD to be kept under a certain % with full load on the circuit.

For the HI it is much tougher as you do not really know what is causing the voltage drop.

Is it loose connections? (Possible hazard)

As has been noted backstab or quick wire methods sometimes lead to voltage drop but those are UL and NEC recognized connections.

Is the circuit overloaded? (Possible hazard)

Is it too much circuit length? (Not a hazard but a performance issue)


Quote:
Sometimes I wish I had never bought the Suretest.


![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

I agree sometimes it's better not to look to deep.


--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN