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Testing ground wiring

B

bleed3r

Limp Gawd
Joined
Jul 30, 2003
Messages
391
In my dorm I'm concerned about the ground wiring.
My APC surge suppressor's wiring fault LED is either not visible or barely visible with nothing plugged into it, but when its being used normally the LED is very red.

I also caught a glimpse of the overload flash a while ago, but I don't know about the frequency of that.

I don't know if this means that there is a grounding problem, or if simply there is not enough power to supply all the rooms in this building? I definatly dont want to kill my computer, fridge, etc. And if I am going to be playing bass guitar, if there is no ground on my amp, I could get fried!

The APC website, upon googling about the wire fault light, has a broken page right now, and I dont have the documentation at hand so I don't know the official word.

Is there a test I can do with my multimeter set to AC to test the ground? Any ideas about this?

BTW, I don't have a rediculous amount of power load or anything at all. Basicly mini fridge, my shuttle, my lcd, computer speakers, and occasionaly printer.
 
It means that the AC wall plug isn't wired/connected correctly.

Tell your dorm monitor to call a campus electrician.
 
ok thanks. I think I will let someone know


Also, my I hear this quiet clicking coming from my shuttle (psu?) and syncronously the overload light on the suppressor flashes with these clicks. I've also heard the clicking when I've shut it down, and goes away by disconnecting power.
 
Yikes! I've been using it all this time. This could possibly be only my room I guess too.
Can you elaborate any more, just so I sound informed on my reasoning for urgent help?
Is my ground faulty?
 
bleed3r said:
Yikes! I've been using it all this time. This could possibly be only my room I guess too.
Can you elaborate any more, just so I sound informed on my reasoning for urgent help?
Is my ground faulty?
Click to expand...
Worst case is the ground is live 120VAC! DEADLY!
That is not likely, but possible. Be safe & just don't use it until it is fixed. ;)
 
Take your multimeter to the outlet, test between the hot (smaller vertical slot ) and ground (u shaped slot). then between the neutral (taller vertical slot) and ground.

You should have 120 volt + or - 5% between hot and ground, no volts between hot and ground = no ground. You should have 0 volts between neutral and ground. You are basically checking proper polarity. If you have voltage between hot and ground, you have a ground, however the quality of the ground really can't be checked without a high dollar tester or physical inspection of the wiring
 
bleed3r said:
I also caught a glimpse of the overload flash a while ago, but I don't know about the frequency of that.
Click to expand...

Doesn't your UPS write events to the system event log?

oboyco said:
You are basically checking proper polarity.
Click to expand...

Polarity? In an AC circuit?
 
mikeblas said:
>>>>>>>
Polarity? In an AC circuit?
Click to expand...

Sure - in much of the world it switches polarity 120 times every second.
But I don't think that's what oboyco meant.
 
Susquehannock said:
Sure - in much of the world it switches polarity 120 times every second.
But I don't think that's what oboyco meant.
Click to expand...
Since the change in polarity is constant, it isn't relevant. Phase it what's relevant. Polarity certainly isn't what oboyco was thinking of, as you it can't be observed with a multimeter at those frequencies.
 
Polarity in AC wiring devices, meaning the hot and neutral on the the proper terminals. On most male cord caps of appliances, lamps etc, the blades of the plug are different sizes so you can only plug them in one way into the receptacle.

For example, a table lamp. The screw shell (the theaded silver part of a light bulb) is intended to be the neutral, which is the grounded conductor. If polarity were reversed, the screwshell would then be the hot. It is feasible to touch the screwshell while replacing a light bulb, hence electrical shock if polarity is reversed. Hot wire on the brass screw, neutral wire on the silver screw on 110 volt wiring devices. There are also other reasons for proper polarity on appliances.

The terminology I'm using is different from that of DC positive and negative, and AC cycles per second (Hz)
 
Hey guys. So I had a guy come in to check out my outlets.

He used a simple plug tester, which basicly denoted no problems.

I showed him how my apc surgearrest shows the building wiring light, and had to explain it's not faulty etc.

Eventualy he opened up the plate and we see there is no ground wire at all. Only, supposedly the box grounds the outlet when it's screwed in.

All he says is that blah blah old building, ground doesnt do much anyways, etc. I'm like wtf telling him how I know how stupid that is, and all he tells me is that if I'm concerned and want my little red light to go away is to buy a GFI.

All the other rooms look properly grounded, except mine and my adjacent neighbors. Why did they skimp on us?

Well I figure that the increasing red light with more items running, and the flashing overload light (over 15A I think) is from the high resistance to ground since it is not actually through a proper wire.


1. Will a GFI really do anything? Could I run a 500w amplifier without death hazard?

2. Is there any way to complain / do anything else? Even though this is an old building, it is supposed to be up to code. I am paying all this rent, and supposed to have a properly wired room. All I got was well, "theres nothing we can do about it , cant run a ground to it now, ground means it only really goes back to the board and into a bigger wire, it isnt important"

And GFI is a Ground Fault Interrupter (which I will google some more)

Edit: With my multimeter between hot and ground, I get 105V from the apc unit which has shuttle lcd fridge on right now. The socket on the other side of my room with nothing in it reads 110V. So I know they're only grounded by the box, and its a seriously crappy ground?
 
Well this is pretty difficult to diagnose without being there, but I'll give it a shot. First of all we need to asume (huge assumption), that the box is grounded. If it is, it is no big deal to provide a grounding jumper, #12 wire from the 10-32 screw hole of the box with a ground screw, to the grounding screw of the receptacle. Best way to do it.

A ground fault interupter works like this. It measures the current between the hot and the neutral, ideally this current is exactly the same. Lets say something goes to ground, like you touch the hot wire and some kind of ground at the same time. This means that some current is going through you.

Ok. so then the current between the hot and neutral isn't the same because some of it is going through you. The GFI then immediately trips and cuts off the voltage. The cut off value is around 5 milliamps difference, which has been determined to be the "safe" current that a human body can take before electrocution.

The National Electrical Code approves the use of a GFI to replace a receptacle that originally (very old buildings) had no ground, just a hot and neutral with no ground provision.

Your best bet is to try to get a good ground to the receptacle from the box. If all else fails, a GFI would be the way to go, but keep in mind that a GFI does not take the place of a good ground, especially in the case of a direct short circuit. Don't know if a GFI will make your light go away.

PS the screws of the receptacle can provide a good ground or some times a half assed ground which can be sometimes worse than none. They do make what is called a self grounding receptacle for that purpose, which has a kind of clip on the screws that provides good continuity between the receptacle screw and the box. Wire between box and recept is better.
 
Hey guys. So I had a guy come in to check out my outlets.
Click to expand...
Have this fool arrested or kill him yourself, you have every right!

Then call the city/county building inspector's office & tell them why you killed him, you will get probation. ;)
 
In almost all municipalities and counties, there is nothing that says all buildings must be brought up to current standards every time a new code comes into effect. This would be next to impossible to be feasible economically and ethically. As long as the building met the code at the time it was built, it is "grandfathered" unless there is a life safety issue.

Granted, the guy gave some untrue information about ground not being important, he wasn't to far off with the GFI advice. My problem with him is why didn't he ground the recept from the box itself with a grounding pigtail? Very easy and simple.
 
bleed3r said:
He used a simple plug tester, which basicly denoted no problems.
Click to expand...

What's the more advanced version of what the plug tester showed?

bleed3r said:
I showed him how my apc surgearrest shows the building wiring light, and had to explain it's not faulty etc.
Click to expand...

I might have missed something. How did you determine the APC SurgeArrest's light isn't faulty?

bleed3r said:
Eventualy he opened up the plate and we see there is no ground wire at all. Only, supposedly the box grounds the outlet when it's screwed in.
Click to expand...

What is it that grounds the box?
 
Ok, I'm going to try and organize this a bit.

I have an APC SurgeArrest surge suppressor. I am 100% positive it is not faulty. I have used it at my home which is properly wired to code. The unit isn't malfunctioning. It was factory tested and there was test receipts and all with stamps and tested by #X employee.

In my dorm, when I plug in the apc unit on one set of outlets the site wiring fault indicator lights up immediately.

see "My Site Wiring Fault Indicator LED is on my UPS/Surge Protector"

This outlet is wired like so:
  • white wire - big slot
  • red wire - small slot
  • screws to receptacle - ground ?

between red and ground I get a measurement under 110V

there is a blank plate near this pair of outlets. In it, there is a box with the red and white wires coming out one hole going into another hole, and there is a random black wire not connected to anything with a cap covering it. Between this black wire and the ground hole, I get a measurement under 110V as well.


On the other pair of outlets in my room, I can plug in my APC unit and the fault light is very dimly lit. With each thing I plug in, the light will get brighter and brighter red. It only takes a few things to make it red (mini fridge + shuttle). The other thing that happen's is that the overload led flashes sometimes, and for each little flash I can hear little clicks at the exact same time coming from my shuttle's power supply.

This outlet is wired like so:
  • white wire - big slot
  • blue wire - small slot (the blue wires are capped to a black wire)
  • green wire - ground (yes there is a ground wire. There is a screw in the receptacle and it is wired to the outlets, but there is no way to tell if the recaptacle is grounded. Only black and white wires come from a hole into it.)
between blue and ground I get about 110V


The electrician who came here, just used a 3 prong tester with 3 leds on it. He said there was no problem. I showed him the APC unit and he first said it must be faulty. Then he said it is too sensitive and there is no problem.

Then we took the cover off the outlet to see no actual ground wire. Then he said something like I don't actualy need it. Then he said oh see it is grounded by the box, let me tighten the screws some more.

I said, "isnt it a shock hazard not having a proper ground?" and he said no.
I told him how I know how dangerous it is not to have a ground, I have experience with some high power music equipment and it is dangerously foolish to not have a ground, and I also explained how if there isnt proper wiring the surge warranty wont count for anything. He replied like, oh ok I see what your saying. Then he said there is nothing he can do, I should get a GFI if I want to make my red light go away.



I've considered finding a way to get a ground from the radiator, (buildings on campus steam heated).

I will take this farther, but I'd like to hear any ideas from you guys. I can't stand having to explain for instance, why having a ground should be important to people. They just look at me like, well are you experiencing any problems? Have to try and contact the electricians boss...


Anyone know what the overload/clicking means? Any clues to the problem with the wiring I explained?

Thanks.
 
At this point I'm not sure what to say. Receptacle=outlet, and I am assuming the APC unit is an uninteruptable power supply, "ups" with surge suppresion . You're not plugging the fridge into the ups are you? If so that's your overload problem, ups can't handle the load.

I'm thinking at this point you should try another known good ups and see what happens. As a general rule the polarity tester is pretty accurate about grounding. Reread again my other posts about a grounding jumper to the receptacle/outlet. If he tightened the screws, I would think that should provide a decent ground.

To my knowlege the fault lights on the ups are similar to those on the polarity tester. Try another ups. If same problem, the wiring needs to be checked out by a professional for ground quality. If not then call the manufacturer and explain in person the exact circumstances, you may have a problem with the unit.
 
id say run the computer without the fridge plugged in and c if u still get the clicking.
 
the clicking/overload light happens no matter what. fridge unplugged doesnt change it.

yeah, this isnt a ups. its a power strip / surge suppressor

by receptacle, I meant the box, I guess receptacle box


Maybe just wiring the ground to the actual outlet instead of just the box will fix that pair of outlets / apc unit will show the ok. I don't know about the other one, with the increasing light and power supply clicking / overload light. I don't really know how to explain this to someone. Anyone would see there is nothing wrong.

Maybe I'll fire something out to APC to see what they can tell me.
 
Try another surge strip, easiest simplest thing you can do, sounds like you have a bad one.
 
It really doesn't make sense to me that it's faulty.

I used it at home, and it worked fine (shows no warnings)
I try it in other guy's dorms, it works fine.
It's screwy in my room and my neighbors.

I sent something to APC. I'd like to hear there say on my symptoms.
 
I suppose you could get shocked or cause a fire in your room.. then when the fire marshall comes out to investigate, say "that electrician was here yesterday and said I didn't need a ground!"

Maybe you'll get some money out of it? :p
 
Well I used some extra 12 gage wire to connect the ground to the box as simply suggested. That fixed the problem, and then I had to semi-permanently ziptie my extension cord to the outlet, going around the plate and outside to keep the plug from coming loose from the aged outlet (very finicky, has to be held in tight for full contact or I get red light still). (... and sorry, no pics of the leet zip tie modding)

Still really don't know what's up with the other outlet with the increasing fault light and clicking power supply... But no matter, I fixed the other one. Still ticked off at the electrician, but w/e. Maybe he'll get shocked in the ass one day.

Thanks for the help guys.
 
Yeah, as you said, the building was "grandfathered" in. I think it would be worth the $6 to get another outlet and a proper pigtail to "ground" the plug, if it's that finicky. Though, it's not as bad as I've seen. Imagine the ground prong....being HOT. That's right. A very wierd plug in the storage room of some building i've worked on had that happen...
 
Glad to hear things worked out. I would definately spend a dollar and replace that receptacle, if it's that loose, with any kind of load, it can burn up on you and possibly worse. If you do make sure your ground pigtail is fastened to the box with a green 10-32 ground screw made for that purpose.
 
I've never wired a hot receptacle. I guess I could just go home and grab one of the "stick the wires in the holes" type. That would be really easy actually.

The box is some really old crap though (from the old day before grounding I suppose). I have the ground pigtail on one of the screws holding in the receptacle; there is no proper green screw or place for one.

The other set of outlets is newer with proper ground screws etc, but I have no clue about its problems.
 
So there is no tapped hole in the box for a 10-32 screw?

You could use a ground clip which attaches to the side of the box.

However at this point I would call someone in and have them replace the receptacle and properly ground it with a ground wire. This is something you do NOT want to do hot. The breaker must be turned off. The newer receptacles with the stab in holes will only take up to #14 wire and won't take #12, for good reason. The stab connections aren't all that great.

Do yourself a favor and have a professional do this for you, and make sure they have a ground wire from the box to receptacle. There are many ways to do this, even if they have to drill and tap a hole in the box, or use a "certified self grounding receptacle.
 
Yeah, I could put in a repair request for that. I might do this at a later point, I've done enough dicking with this and I'm worrying about midterms. Thanks for the suggestion, I think it is a good idea to get this receptacle replaced.
 
I once lived in an apartment that had really old outlets. They were grounded, but they were so loose that a regular plug would not stay put, and any wallwart would just fall out. I bought some replacement outlets at K-Mart for like $2 a pop, and all was well.

Get the screw type, as they can take bigger wire, as mentioned above. It's best to let a real electrician do the swap too; I got the shock of my life when I went to replace my bathroom outlet with a GFCI type, and I didn't realize that the bathroom was on a separate circuit from my room. :eek: It was worth it though, as I didn't want to wait a day or two for the repairman to come and do it.

Good thing I work with one hand behind my back. ;)
 
I agree, use the screws. Most plugs you buy nowadays from Home Depot have both the stab connections and the screws on the sides. Use the screws; it's a hell of a lot more secure.
 
one thing i think is wierd is how in a breaker box the ground is also connected to the same post as the neutral :confused:
 
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