Speaking of ground problems

[Jim Barrett 0]

Perhaps somebody can give me some advice..I'm an E.T. not an electrician but I know this is wrong.

 

Had a location where an older DIY camera/DVR system went belly up. It was failing for quite a while & since it was a cheap POS I declined to service it.

 

After it died an unexplained and unlamented death I was asked to replace the system. Within about a week I got a call that the DVR was locked up and unresponsive. I was kind of busy so I went out, turned it off and when it came back up everything was working. I shrugged my shoulders & told 'em to let me know if it happened again. About a week and a half later, same problem.

 

Just to cover my bases I stuck a meter on the AC power line and to my consternation the AC voltage wavered between 104 volts and about 108 volts, across hot and neutral. This was a three prong grounded outlet so I checked and found the 104-108 volts from hot to ground, but about 5-8 volts between ground and neutral. Not right, I said to myself.

 

I looked around the area and found three different kinds of outlets in the same room. The original (1920-30's?) outlets were non-polarized, two prong outlets, one to a plate, nice solid 115V. The second kind were new surface mount, conduit on the wall, three prong grounded outlets (computers plugged into these), nice, steady 115V w/ no surprises between neutral and ground. The others were like the one I was using, existing retrofit, in the wall, as if someone took the old outlets off & slapped on a 3-prong grounded outlet & attached it to the existing box.

 

I called in the guy responsible for the building maintenance, explained my problem to him & told him he needed to get an electrician out to take care of this neutral - ground problem & that I was concerned for the long term life of the new equipment to say nothing of the rest of the electrical system. I then stuck a relatively robust surge protector on the line , plugged my equipment in & left. I documented my concerns in writing to both the users & the maint. guy.

 

Well, two months have gone by with no word so I stopped by to check up on them. No more problems with my equipment but nobody did anything about the AC either.

 

How concerned would you guys be? This strikes me as a situation that's not right and could be potentially dangerous but since I've documented my concerns to the appropriate people I kinda feel I've done my part.

 

Any thoughts about this &/or if I need to deal with it further? I told them that damage to the DVR might not be covered by warranty if the MFG thinks it was surge damage or something like that.

 

My quotes & proposals always state that AC power is the customer's responsibility but I'm uncomfortable with this.

[Lolo Wolf 0]

If you want to pursue the matter can you get access to their panel? (main circuit) what is the type-AMP, condition, wire size of the breaker(s) buss conects tightness and condition of connects in question possible miswire , reverse conects, overload or illegal wire practice etc that is feeding all that mix? did you find differnt size wire in use at the outlets you tested... are there continuous runs of the same type wire or a mess of spliced add ons between receptacles is there a working ground in use on these retrofits? You stated "I then stuck a relatively robust surge protector on the line , plugged my equipment in & left." most suppressors and EFI filters

require real grounds. Any that don't are next to useless is there a GFCI outlet present by any chance hidden somewhere upstream before the outlet(s) in question....GFCIs are a legal substitute for a grounded outlet in an existing installation where there is no ground available in the outlet box. but should be labeled and it makes the circuit safe for you it doesn't make it safe for your equipment - you need a ground to make surge suppressors or line filters effective. You were 100% correct to verify the line voltage of any outlet PRIOR to plugging your product into it, after finding their faults most likely unsafe illegal and incorect wiring you documented the noted errors. Low AC line voltage may be a temporary condition due to heavy demand on the utility at peak times, If the building you are in happens to be "at the end of a line" in the distribution system, low AC line voltage may be the "norm" (but it should never be below about 110 VAC).

[Jim Barrett 0]

No, not really my problem to fix, I don't think.

It's pretty obvious there is a problem & it's not of my doing.

I'm just wondering if the building is in danger of burning down or something.

 

I'm not an electrician & don't really want to be one.

[C7 in CA 0]

No, not really my problem to fix, I don't think.

It's pretty obvious there is a problem & it's not of my doing.

I'm just wondering if the building is in danger of burning down or something.

 

I'm not an electrician & don't really want to be one.

 

Loose connections can show as an undervoltage, and loose connections get hot and can cause fires so yes the building maybe in danger of catching fire. But the good news is the building probably won't burn down if it has a working fire sprinkler system.

 

I would put in a battery backup with Automatic Voltage Regulator. Set the regulator/audible alarm and tell the client every time they hear the alarm it's because the voltage has dropped or exceeded unacceptable levels.

[scorpion 0]

http://scorpiontheater.com/surge.aspx

 

I am not an electrician, but I wanted to put in my two cents

 

 

Here in Florida the average DVR, Computer, or Home Theater equipment, and other electrical devices will not survive the electrical impulses whether the power company is changing from one generator to another, or lightning is striking near by (none direct), or you have an electrical device on the same circuit that can be effected by an AC compressor, or other electrical devices. This is noticeable when the lights flicker when some device "kicks" on.

 

I always recommend a surge protector on electrical devices such as Home Theater Products, Security Devices such as DVRs, Computers, and on Televisions.

 

BEWARE!

 

For those of you who may not be aware of them. There are two kinds of surge protectors. "True" surge protectors, and "false" surge protectors.

 

I say "false", but what I am saying it that the surge protector manufacture uses one device called an MOV to do the actual "dampening", and it may have a lower JOULE rating, and they may have another MOV in parallel that does not provide the true protection, but it has a higher JOULE rating so that they can put that number on the box!

 

There are other companies that install MOVs to provide the "dampening", and it will have the true JOULE rating, and that is what you will see as the JOULE rating on the box.

 

Now are you confused??

 

Just look for the UL 1449 on the box of the surge protector. This may help you from the entry level crap that may not be UL 1449 protected. Then again, what stops a company that is non UL compliant to post this on their box?

[Jim Barrett 0]

I agree with Scorpion about the surge protectors. Always use them, practice safe power techniques. The previous system in this instance had a surge protector on it and I just reused it. When the problem surfaced I didn't know where things were going so I stuck in the protector I usually use so I could eliminate that as a concern.

However, I'm kinda confused because as I indicated and others have pointed out, I have a lousy ground. When I walked away I told myself that without a decent ground I had my doubts about the effectiveness of the surge protector.

But, 6 weeks later the problem has not returned.

"The observed phenomena requires no explanation, it simply exists."

Over the years I've noticed a lot of Mfgs putting MOVs right in the equipment. When I worked in the Sat TV business several years ago all our stuff had them built in. Until they were gone. I used to teach my techs that if they found an unexplained dark brown smell inside a piece of equipment they should look for the bare leads where the MOV used to be. Used to tell the customers that they had released the magic smoke & now they had to send it in for more.

But, at one time or another I've had to deal with just about everything from direct strikes (hardly anything ever survives & I wouldn't trust what does for mission critical use) to repeated inductive surges where the lights in the neighborhood dim when the foundry fires up.

You pays your money and takes your chances.

[scorpion 0]

When the foundry fires up!!

 

Holy smokes!

 

I want to open a small electronics store in that town!!

 

What city is that again??

[Lolo Wolf 0]

My response was to the Power Quality issues the poster questioned I am not saying not to use suppression devices Its a given, electronic equipment is highly sensitive to Power Quality problems, which can slowly over time and repeated occurances fatique, damage or destroy semiconductor devices, such as microprocessors and dedicated-purpose electronic circuit chips. If the wiring where the poster found issues and he did is not flexible enough to allow separating inductive and switching loads from sensitive loads, may have to add a dedicated, isolated ground circuit for marked for electronic equipment only. The wiring may not be supplying power of correct polarity or providing proper grounding - The building system ground may have high impedance, there exisits a 2-wire system that has had 3-prong outlets installed. perhaps illegal neutral-ground bonds, or ground loops that let unpredictable voltages to float on the grounding circuit. These wiring problems can cause equipment to act strangely Stopping and starting at irregular intervals or work one day disconnect reconnect then work ("Magic") or just plain fail, any of these issues or combination I think will prevent even the greatest latest surge suppressor from protecting your equipment over time.... Really not trying to be argumentive and this issue has been discussed before with some very informitive info on the forum past, since then standards have changed added to the UL 1449 spec as well. All in all... even if it is carved in stone to me its all about guidelines and stones have a funny way of cracking for no apparent reason over time....not to be argumentive but I stand by my statement to the original post....most suppressors require real grounds (working ground) I am glad to read your device is working without issue and you dont have to chase down further problems with the location. Regards

[C7 in CA 0]

Yeah, just to add...

 

A N-G potential is not uncommon especially on long or heavily loaded circuits. Unplug every thing from that circuit and you will probably see 0 or at least much less potential.

 

If it were me I would at a minimum confirm the circuit isn't overloaded. I always keep in mind that just because there is an available outlet doesn't mean there is available capacity. For instance a 20 amp circuit is only allowed 16 amps continuous (If I remember correctly). So if that circuit has 16 amps on it and I plug in a DVR I just overloaded that circuit! I'm pretty sure that would make me liable for any damages related to the overloaded circuit.

[Jim Barrett 0]

Come on guys, cut me some slack here.

Do you guys track down all the outlets in a building ckt before you plug equipment into it?

Once you've gone back to the breaker do you measure the load? How do you do that without opening the breaker panel? If you're not an electrician are you comfortable doing that?

I'm a one man shop here in Milwaukee (and yes, there are fewer foundries than there used to be but I used to service radio & video in some of them) and being old and decrepit I keep the jobs I take down to a size I can handle. Most of my customers/clients would balk at the thought of having to pay someone to put in an isolated dedicated ground ckt. If you check other discussion groups you will find an endless number of opinions about dedicated, isolated grounding issues. The buildings I work in are almost always old (I seem to specialize in ugly building installs) and the power systems are almost always various degrees of upgrade.

Ordinarily I specify that AC power is the customer's responsibility and don't get involved unless there is a problem. In this specific case the building is probably over 80 years old and as I said earlier there are a variety of outlet styles. The fact that there are surface mounted outlets for their computers indicates that the owners are of aware of the lousy power circumstances. My best solution is to get them to provide this system with the same kind of power they put in for their computers & I'll keep after the maint. guy to do just that, telling him and the users that they are likely shortening the life and or endangering the operation of thier video system unless they do. I was just wondering if you guys thought maybe the building was in danger of burning down? I don't think this is anything new for this building but it's not right & if it were mine I'd see to it that it was right.

I love these discussions. Being one guy, it helps to get input from other informed minds. On any given day there's probably a couple thousand years of combined experience here. I'm tempted to say something about the differences between the ideal world and the real world but that would presume my world is your world and I would'nt dare do that!

[C7 in CA 0]

Sorry Jim, I didn't want to come off like i was on you about something. I like that you actually broke out the voltmeter instead of just shrugging your shoulders and walking away like many would. And like you said, this makes for good discussion about problems we all run into eventually.

 

I too probably wouldn't have thought twice about originally just plugging into that outlet and calling it good. But the fact that you suspected electrical issues then tested it and found a possible problem you kind of own that problem if you continue to use that outlet. imho. For all I know there may be no problem with the circuit. But if you are uncomfortable with the situation, you probably have good reason to be.

 

Personally I would not have a problem opening the panel and clamping an ammeter on that circuit to have a look. (unless the panel is a Federal Stab-loc ) But short of that, I would use an extension cord to a better outlet instead of continuing to use a suspect outlet. But then you run into the problem of using an extension cord on a permanent install! No easy answer when the client wont take responsibility for their electrical issues.

 

And to answer your question. In my opinion I don't know that the building is in danger of burning down, but the symptoms are curious enough to have checked out before using the outlet...

[Jim Barrett 0]

No Problem, notice I was laughing.

Is that a form of "finder's keepers"? You found this problem & now it's yours!

I suspect the best of us are kinda like that...we live for the puzzles and this one's mine

You know, I thought about going over there with an extension cord and some duct tape and running the cord over to an outlet w/ a computer plugged into it & taping it down. When they wanted to plug something else in they'd have to unplug the cord & the video system would go down. Probably at that point the situation would be irritating enough to cause them to do something.

If the equipment malfunctions again that is exactly what I'm going to do. Bet my problem goes away then!

But you've got a point there about my unease. After a while in the business you develop instincts (if you don't you're probably in the wrong business) that should be listened to. My gut says this problem is probably bad for the equipment in the long run but that the building has probably been like this for 25-30 years.

But bottom line is there are several volts of potential running around there someplace, with 15-20 amps of possible current & I'm not interested in getting into a conflict with it.

Several years ago I was working for the local school system and found (the hard way) a suspended ceiling grid with 70 volts AC on it. You can imagine the process involved in tracing the problem to an emergency alert receiver (portable plug in radio thing) with one side of the AC line on the chassis. The radio was sitting on top of the PA console (which had 70v AC on it). The console was tied to a conduit which ran up into the ceiling, contacting the ceiling grid on the way.

Turned out that the school system had several hundred of these radios and about 75% of them had this ground fault. Turned out that the electricians knew that some places were floating hot but were'nt interested enough to find out why.

The problem was dumped on me and I eventually threw away all of those receivers & replaced them. If memory serves me correct I traced the problem to some dried out caps in the power supply.

Expensive fix but that was probably 20 years ago & the "new" stuff is still working like a champ.

Thanks for the input every body!

[Lolo Wolf 0]

Jim Barrett Wrote:

"Do you guys track down all the outlets in a building ckt before you plug equipment into it?". Jim my response simply is no however I do go check the main panel (site survey) prior to accepting the work. I agree and can appricate your "ugly building installs" spent years crawlin around K&T and the countless nightmares of so called "upgrades". Old doesnt always mean bad but oversite is needed with maintaing such systems with extra attention to mechanical condition of all visible paths and connects.... unfortunatly its often what you cant see that kills ya or burns ya down. Regards

[Soundy 1]

Just to cover my bases I stuck a meter on the AC power line and to my consternation the AC voltage wavered between 104 volts and about 108 volts, across hot and neutral. This was a three prong grounded outlet so I checked and found the 104-108 volts from hot to ground, but about 5-8 volts between ground and neutral. Not right, I said to myself.

 

I looked around the area and found three different kinds of outlets in the same room. The original (1920-30's?) outlets were non-polarized, two prong outlets, one to a plate, nice solid 115V. The second kind were new surface mount, conduit on the wall, three prong grounded outlets (computers plugged into these), nice, steady 115V w/ no surprises between neutral and ground. The others were like the one I was using, existing retrofit, in the wall, as if someone took the old outlets off & slapped on a 3-prong grounded outlet & attached it to the existing box.

 

[snip]

 

Well, two months have gone by with no word so I stopped by to check up on them. No more problems with my equipment but nobody did anything about the AC either.

 

How concerned would you guys be? This strikes me as a situation that's not right and could be potentially dangerous but since I've documented my concerns to the appropriate people I kinda feel I've done my part.

 

Any thoughts about this &/or if I need to deal with it further? I told them that damage to the DVR might not be covered by warranty if the MFG thinks it was surge damage or something like that.

 

My quotes & proposals always state that AC power is the customer's responsibility but I'm uncomfortable with this.

 

Maybe a stupid question, but can you not just plug the DVR into one of the other "clean" outlets?

 

Specifically, I'd pick the one farthest away from the DVR in the room, and run a big thick gaudy orange extension cord to it. Right across the middle of the floor.

 

Make a point of the fact that this is required for stable operation of the DVR, and the only fix for it is to have the other outlet properly repaired.

 

Once someone with some clout trips over it, it should get fixed in short order

[Jim Barrett 0]

Sure, see my previous post but instead of across the floor I'd run it up and around a door frame & secure it w/ duct tape. That way it's unlikely that anyone would trip on it but every time they walk through the doorway they have to look at it. Best if it's the entry to the boss's office.

I often use the annoyance factor to get people to comply with the technology I install.

[Soundy 1]

^Ah yes, I see that now! Good thinking

 

The problem was dumped on me and I eventually threw away all of those receivers & replaced them. If memory serves me correct I traced the problem to some dried out caps in the power supply.

Expensive fix but that was probably 20 years ago & the "new" stuff is still working like a champ.

 

I hope you added a hefty "annoyance surcharge" to the no doubt already steep hourly labour charge on their bill...

[Lolo Wolf 0]

Personally I wouldnt walk away from a build with a extension cord laying across a traffic area (tripping hazard) let alone taped to a wall or around a door frame...from previous forum posts past on the subject of codes and safety Im sure I will get flak on this but - (NEC) -Extension cords cannot be used as a substitute for fixed wiring [400.8(1)], and in addition cords can only be used for temporary wiring if approved by the authority having jurisdiction (AHJ) [590.2(B)]. temporary wiring is only permitted for construction, remodeling, maintenance, repair, or demolition of buildings, structures, equipment, or similar activities or for emergencies and for tests, experiments, and developmental work. When temporary wiring is permitted by the AHJ, the wiring (cords) must be removed immediately upon completion of construction or purpose for which the wiring was installed [590.3]. In past build disscusion on site with a client I noticed the extensive use of extension cords/powerstrip usage in a crowded office building and noted to the owner some info on Power strips: device is not classified as a cord set or extension cord, but is referred to as a "Temporary Power Tap" (TPT). It is permitted to have six "outlets" because its over-¬current protection will protect the #14 AWG cord at its rated value of 15-AMPS. A "TPT" is intended only for indoor use as an extension of the branch circuit. (UL 1363) Unlike extension cords- the word "temporary" is broadly interpreted because of the special need for the extra outlets where a cluster of devices exsits-this assembly may be used , but its length is limited to a maximum of 25-feet.- UL (policy) considers this usage to be within the intent of the cord because such equipment is moved occasionally, and because there is no other practical way to provide for this common need. The main difference between temporary power taps and extension cords lies in the intended use of the products. UL lists extension cords as cord sets under the category of Cord Sets and Power Supply Cords. A cord set can have a current rating less than the branch circuit rating (depending on the ampacity of the cord and the rating of the devices) Temporary power taps extend the branch circuit and note that Securing an extension cord to the structure is not permitted as it would constitute

a non temporary use under NEC 400-8. Now with OSHA -OSHA standards are based upon, and to a large extent, extracted from the National Electrical Code. They are, more restrictive in some instances (e.g. 1926.402a). The NEC is more detailed and more specific and is enforced by most cities, counties and states. It is important in corporate/industrial/commercial environments in regard to personal liability actions, therefore the NEC tends to dominate. Coming from a heavy/construction commercial/industrialbackround I cant or would overlook or knowling avoid safety and code.