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Suretest - again


Jaykline
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I'll be making a trip to the big city (north dallas) tomorrow to buy my first Suretest Circuit Analyzer (61-155 version). I've read through several posts on this and other forums that discuss the notion of HI's pushing the limits of a "limited visual inspection" and the part that Suretests in the hands of a generalist play in that. My question is kind of a subset of that larger philosophical thread:

How many of you measure and comment on Voltage Drop? And what's the bad news related to voltage drop anyway? Seems to me, the real issue is that a high voltage drop could be an indication of a condition that should be pointed out because it could lead to other problems. Trouble is: If I measure it and mention it, I'd like to be able to tell my clients WHY voltage drop is an issue they need to be concerned about. And why they should be willing to pay to consult with a licensed electrician about finding a remedy.

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I love my Suretest, have nearly worn one out and am getting ready to buy the new one with arc fault testing capabilities. One of the great advantages in addition to identifying voltage drops that are indicitive of potential fire hazards is in being able to detect bootleg or false grounding.

My own boilerplate comment follows. I think it speaks to the issues you mentioned. I look for patterns when I find troublesome drops. Things like solid aluminum wiring, sporadic problems or problems associated with one obvious circuit. I usually don't mention it if there are only 1 or 2 outlets in a house under 7%.

Only a representative number of the electrical outlets were randomly tested during this inspection. When a 15 amp load was applied, voltage drops between 7.6 % and 9.3% were noted at the wall outlets ___________. Electrical safety standards require that voltage drops not exceed 5%. Drops over 8% are generally considered to be very hazardous. Excessive voltage drop indicates damaged conductors, poor connections/splices, overlong circuits and/or undersized wires. All of these conditions present potential latent fire hazards due to potential arcing or overheating. In most cases the cause is a poor or loose connection at the device or switch due to the use of inferior push in type connections rather than the screw down type and replacement of the outlet or switch will correct the problem in many cases. This test is very specialized and is beyond the scope of what is required or typically performed in a home inspection, building inspection by local inspectors or by electricians at the time of construction. It is performed solely as a courtesy for buyer clients in the interest of life safety. Again, not all, but only a representative number of outlets (1-3 per room) have been tested. A full evaluation of the system is required to determine if this condition exists at other untested locations and is recommended. More comprehensive testing or follow up testing can be performed upon request. After repair, re-testing under load is advised. I offer this service. Please call if interested.

RECOMMENDATION : Further evaluation and correction by a qualified state licensed electrician

and follow up testing.

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Originally posted by crusty

Electrical safety standards require that voltage drops not exceed 5%.

Do you have a source to back up that statement? There is a fine print note in section 210-19, but, as I hope you know, fine print notes are not enforceable. They certainly don't justify the use of the word "require."

Drops over 8% are generally considered to be very hazardous. Excessive voltage drop indicates damaged conductors, poor connections/splices, overlong circuits and/or undersized wires. All of these conditions present potential latent fire hazards due to potential arcing or overheating.

Again, can you back that up? The FPN I mentioned above relates specifically to "efficiency of operation." It has nothing to do with safety. The statement that "Drops over 8% are generally considered to be very hazardous" is, at best, inaccurate and possibly irresponsible. If someone challenges you on this and you're unable to back up your statement, you'll lose credibility.

I don't like excessive voltage drop for many reasons, but none of them include safety. Think about it this way: the National Electrical Code has been around for over 100 years. Hundreds of the brightest minds in the electrical industry have contributed to its refinement over that time. Its very purpose is to safeguard people and property from the hazards of electricity. The most damning thing that the NEC has to say about voltage drop in branch circuits is that keeping it under 5% will provide "reasonable efficiency of operation."

- Jim Katen, Oregon

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FPN 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, will provide reasonable efficiency of operation. See Section 215-2 for voltage drop on feeder conductors.

Thanks for your concern Jim. Your reference section in the code is correct. Here is the commentary that accompanies it as well.

"Improper voltage due to a voltage drop in supply conductors is a major source of trouble and inefficient operation in electrical equipment. Undervoltage conditions reduce the capability and reliability of motors, lighting sources, heaters, and solid-state equipment. Sample voltage-drop calculations may be found in the commentary following Section 215-2(b), FPN No. 3, and following Table 9 in Chapter 9."

As far as enforceability goes as a HI that is not my problem. You must have me confused with a code enforcement official. As far as challenges go I stand on my statement and challenge anyone to disprove it. All of the conditions that I stated as being attributable to excessive voltage drop are latent fire hazards and all defy the intent of the code. As I am sure you are aware the intent of the code always takes precedent over the letter and I stand pat on my interpretation based on these facts:

1) The NEC is first and foremost a safety code. If you doubt this please trace its history back to the reason and need for its creation as the first building related code in this country.

2) I am unaware of any other cause for voltage drops encountered using the Suretest other than those I described and all 3 are documented latent fire hazards. If anyone can provide me other reasons for excessive voltage drops encountered with the Suretest, I would love to learn about them and may change my position as a result, but please familiarize yourself with the testing procedure and how it is performed before commenting.

I consider the first and foremost part of my job to be addressing safety issues for my clients. If I err I hope it will always be on the side of caution. Frankly, I don't care if it is enforceable. That kind of nitpicking makes no difference to me. If I can get my clients' attention and alert them to a potential safety hazard through the interpretive fog of the real estate sales agents, I've done my job and will continue to use whatever language ("require" I will consider anything written in safety codes a requirement unless specifically excepted) will get their attention.

My job is to identify and describe potential material defects. I then defer the discovered condition for further evaluation. I love the Suretest and consider it a great tool for discovering latent life safety issues that no other inspection technique (other than infrared heat discovery technology) can detect. I typically find that those who generally take exception to the tool are more concerned with pissing off their referral sources than watching out for the safety of their clients. Not a personal observation or attack, I don’t know you yet, just a broad general observation. IMO there are only 2 logical reasons to take exception to Suretest testing methods. The most common being the one I just described or the less common one of doubting the findings and their validity when using the tool. Of course there is a third one….ignorance, but then that isn’t logical. If I couldn't find code corroboration on this safety issue I would still call it based on the facts that I presented in the comment.

Oh, BTW, 8% is the drop value adopted by the city of Public Housing Authority in Philadelphia (I am almost sure but it could be another large eastern city)to detect faulty wiring buried under cellulose insulation that had become what they considered to be a major fire hazard. Somewhere between 11% and 14% is my personal freakout level where I go to the car and get out my soapbox and megaphone for the post inspection conversation with the client.

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I don't get that excited about voltage drops of less than 10%. Last year I bought a graphing, recordable digital oscilliscope and to learn how to use the record feature I left it plugged into my 20 amp washer circuit for a couple of days. Line voltage varied on that circuit from 111 volts to 123 volts over a 48 hour period. Oddly the lowest voltage was recorded on two consecutive days very early in the morning around 2:30 am when the homes electrical loads were almost nil.

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With all due respect Chad we are talking apples and oranges here. The Suretest checks the voltage and records it then it applies a 15 amp (supposed, but I have been told actually about 12 amp) load and checks the voltage under load. It then calculates the percentage drop. It has nothing to do with what the power company is delivering.

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After using my sure test for a year I changed how I view voltage drop.

1. All circuits will have some drop.

2. The longer the run the greater the drop.

I changed my reporting to over a 5% increase in a circuit.

For example first outlet has a VD of 5% and the next has a VD of 10%.

This indicates a bad connection and something that may need repair.

If I check the first outlet (100 feet from the service panel)and it has a VD of 6% the next is 7% the next is 8% the next is 10%. I can bet that they back stabbed the outlets but I don't get very concerned.

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Hi, errr Crusty,

My point is voltage variance presents a problem for the load device if it exceeds the parameter where the device will operate safely. I'd bet that most devices will operate safely in the 90% to 105% range of specified voltage. If the voltage drop was critical in that range, more stringent guidelines would be applied.

Don't mistake my opinion for an endoresement of a 10% percent voltage drop, but current will increase as voltage drops until it kicks a circuit an overload device. The real danger is mostly to the windings of motors.

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Hi,

I think Chad is correct. Electrical devices are supposed to be designed to operate in the 108 to 132 volt range. So, unless you drop below 10% of the 120volt nominal, you are in a safe range for whatever is operating off that circuit.

Scott is also correct, voltage drop is affected a great deal by distance from source. Think of water through a pipe. The farther from the source, the less pressure water has, unless you up the size of the pipe. With wiring it is the same way. An outlet 100ft. from the panel can easily have a drop of 10% but have perfectly good connections all the way to the panel. The issue then becomes a question of delivered voltage at that distance, which won't be within parameters. The correction is supposed to be a larger pipe (conductor). If not, delivered voltage is insufficient and whatever is being powered could be at risk.

My understanding anyway. Don't rely on it - in my mind electricity and voodoo have similar properties.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by crusty, in part:

.......As far as challenges go I stand on my statement(s) and challenge anyone to disprove it.

Well, that's very safe, in addition to being exceptionally self-serving.

Having suffered through 120 hours of fire science class in the mid 80's, we proved it wrong on a daily basis. Unfortuneately, I don't have the paperwork available; I threw it all in a dumpster about 15 years ago. That's OK; those inclined to frenzy are usually dis-inclined to believe research that doesn't reinforce preconceived notions.

Overheating wires, creating fires, or otherwise causing unsafe conditions was the sole intent of our lab sessions; no one was ever able to start an electrical fire, and voltage drop >40% was necessary to even begin to make something warm. Wild hi voltage sparks were sent through tissue paper & dust, & getting something to ignite required extra exceptional efforts. #14 AWG wires were subjected to sustained loads of 30 amps for periods of hours on end without ever getting noticeably warm. In one of the experiments, we wrapped #14 in tissue, wrapped that in newspaper, wrapped that in insulation, then placed the whole thing in a sealed box w/ an interior temperature of 140degF, then subjected it to another 24 hours of continuous 30 amp load. After 24 hours, the wire was not noticeably warm beyond the 140degF ambient. Being unable to start really good fires was bummin' everyone out.

Point being, the NEC is an exceptionally conservative document, & if one is within bounds on stated rules, one is very safe. Applying freakout status to minute excesses noted only in FPN's is conjecture bordering on silliness. Getting out a bullhorn only serves one's need to be loud, not educational.

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Originally posted by kurt

Originally posted by crusty, in part:

.......As far as challenges go I stand on my statement(s) and challenge anyone to disprove it.

Well, that's very safe, in addition to being exceptionally self-serving.

Having suffered through 120 hours of fire science class in the mid 80's, we proved it wrong on a daily basis. Unfortuneately, I don't have the paperwork available; I threw it all in a dumpster about 15 years ago. That's OK; those inclined to frenzy are usually dis-inclined to believe research that doesn't reinforce preconceived notions.

Overheating wires, creating fires, or otherwise causing unsafe conditions was the sole intent of our lab sessions; no one was ever able to start an electrical fire, and voltage drop >40% was necessary to even begin to make something warm. Wild hi voltage sparks were sent through tissue paper & dust, & getting something to ignite required extra exceptional efforts. #14 AWG wires were subjected to sustained loads of 30 amps for periods of hours on end without ever getting noticeably warm. In one of the experiments, we wrapped #14 in tissue, wrapped that in newspaper, wrapped that in insulation, then placed the whole thing in a sealed box w/ an interior temperature of 140degF, then subjected it to another 24 hours of continuous 30 amp load. After 24 hours, the wire was not noticeably warm beyond the 140degF ambient. Being unable to start really good fires was bummin' everyone out.

Point being, the NEC is an exceptionally conservative document, & if one is within bounds on stated rules, one is very safe. Applying freakout status to minute excesses noted only in FPN's is conjecture bordering on silliness. Getting out a bullhorn only serves one's need to be loud, not educational.

I agree with you Kurt and Chad. The voltage drop is not nearly as much of an issue as current drop/load, which is protected by the breakers/fuses. Total circuit voltage will fluctuate by the percentages noted previously. In a parallel circuit, which is how residential circuits are wired, for all intents and purposes, voltage is constant across each parallel leg. Only the current drop, and ultimately...the voltage drop, will very (in theory) based on the resistance of the device it is passing through, i.e., a wall outlet, a wall oulet powering a toaster, or a common fixed wired light, or a light attached to a ceiling fan. All these devices will present different resistances to the circuit, but only the current is supposed to fluctuate with the different resistances. In theory, the total circuit leg voltage will be constant. The voltage "drop" across different devices will vary upon those current and resistance changes in the attached device.

V (Voltage) = I (Current) X R (Resistance)

However, there are other factors that will allow voltage to fluctuate as Mike, Chad, and Kurt have indicated, such as the service supply from the energy company.

10-15% voltage drop across a device or in one parallel leg is nothing to be alarmed about at all. Current drop is much more of a concern and if there was a problem with excessive current drop/load, then your breakers and fuses would be tripping and blowing indicating a problem.

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Originally posted by crusty

I typically find that those who generally take exception to the tool are more concerned with pissing off their referral sources than watching out for the safety of their clients. Not a personal observation or attack, I don’t know you yet, just a broad general observation. IMO there are only 2 logical reasons to take exception to Suretest testing methods. The most common being the one I just described or the less common one of doubting the findings and their validity when using the tool. Of course there is a third one….ignorance, but then that isn’t logical.

As I haven't taken the Sure Test plunge yet, I'll leave this debate to those who have. But I don't see anyone taking exception to the tool or its use, just certain statements in the given boilerplate.

Brian G.

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I use a SureTest every single day. Love it. My standard statement for a loaded voltage drop is:

The outlet in the (pick a room) indicated a loaded voltage drop of >5%. This may indicate a loose connection at some point in the circuit. A more in depth evaluaton by a licensed electrician is advised.

My opinion: a finding outside the norm, good use of weasle words (may indicate), defer, defer, defer. I write what I see and let the client make the decision.

Walker

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Ouch!!

Weasel words are for brokers and lawyers. Why not just tell clients what you find? If you don't understand it, tell 'em that too (I do), but weasel words? I want Chad to come over my house and punch me hard in the throat the day I start weaseling.

Weasel words don't cover your arse, they enlarge and expose it. Give it to them straight. They can handle it.

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Ditto what Walker said, but of late I have been trying to make my comments more educational. I've found that helps the client put the issues in perspective. Interesting findings on the overheating, and good information on equipment performance but those issues have always been the least of my concerns. It's the arcing from loose connections or a potentially nicked wire in the wall that scares me and that possibility will always cause me to throw up a flag. Based on the information I read here I think I'll amend my comment to play down the overheating. I consider the other issues serious enough that I don't want the comment to be discredited. Thanks guys, I learned something here today.

Kurt, in future postings I'll do away with the figurative stuff and keep it real for ya.

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Once again we attempt to compare apples and oranges Mark. My Suretest has been dipped into well over 50,000 receptacles and I get to read every one of them. Often I will come back and retest a couple of minutes later. Yes I get fluctuations when used with or without the extension. Yes I may get a 10.8% drop one time and an 11.5% drop the next. Yes there will be fluctuations dependent upon what voltage is delivered to the outlet at that time. No, I have never gotten a 10% reading on one pass and a 2% reading on the next pass. The point you are missing is in how the tool makes its test and what the significance of those results are as they relate to potential loose connections and damaged conductors. I have checked outlets day after day and have found the tool to be accurate. Maybe you should enlighten us on what your test yielded Mark.

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10-15% voltage drop across a device or in one parallel leg is nothing to be alarmed about at all. Current drop is much more of a concern and if there was a problem with excessive current drop/load, then your breakers and fuses would be tripping and blowing indicating a problem.

I beg to differ.

I tested a outlet on a bedroom wall and got a VD of 8%. 6 feet down the same wall I test the next outlet and got a VD of 14%.

The electrician called me when he got to the house to ask me what the problem was.

I explained where I found the volt drop and told him I thought there may be a bad connection somewhere in between.

He called me back an hour later and informed me that someone had installed an additional outlet in the linen closet (on the other side of the wall) and that the wires at that outlet were loose and melted. (the outlet was covered with towels)He wanted to know where I bought my Suretest so he could go get one.

Doug Hansen has a similar story about someone covering a junction box with loose connections behind a bathroom mirror. He found the problem with a Suretest because of the voltage drop.

I say again 5% increase in the same circuit may indicate a problem.

(Kurt, next time you do those tests, don't forget to plug it in.[:D])

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Originally posted by swarga

I beg to differ.

I tested a outlet on a bedroom wall and got a VD of 8%. 6 feet down the same wall I test the next outlet and got a VD of 14%.

The electrician called me when he got to the house to ask me what the problem was.

I explained where I found the volt drop and told him I thought there may be a bad connection somewhere in between.

He called me back an hour later and informed me that someone had installed an additional outlet in the linen closet (on the other side of the wall) and that the wires at that outlet were loose and melted. (the outlet was covered with towels)He wanted to know where I bought my Suretest so he could go get one.

Doug Hansen has a similar story about someone covering a junction box with loose connections behind a bathroom mirror. He found the problem with a Suretest because of the voltage drop.

I say again 5% increase in the same circuit may indicate a problem.

(Kurt, next time you do those tests, don't forget to plug it in.[:D])

Absolutely. It may indicate a problem. Or not. Neither story makes me think about minor VD even one little bit. In the lineup of potential hazards in a home, it is another one.

The point was/is that the NEC is an extremely conservative document, & they don't think it's significant enough to include it as a requirement. For the time being, that's good enough for me. If I started to make up my own rules for what is right, things could get complicated.

How many times does one discover minor VD & there is a red herring chase for conditions that are never discovered? How many times does one test an outlet & get conflicting results? When one has the coolest hammer, everything becomes a nail.

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For me the key is to use the hammer judiciously. When I find a drop over 8% I dig a little further. Often I am able to quickly isolate the loose connection in the manner Scott mentioned. Often it's a telltale sign about solid aluminum wiring connectivity. Sometime it's a loose connection at the circuit breaker, a very common occurrance where FPE Stab Lok panels are concerned. All in all a great tool IMO.

I believe if we were to dig into the NEC a little we would specifically find that it prohibits the use of dmaged wire as well as loose potentially arcing connections.

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