Old Apartment Bld

[sjaniga]

I was called today to look at giving a quote on adding GFCI receptacles throughout a 148 unit apartment building, in the kitchens and bathrooms, this job is about 60 miles away and we are not scheduled to go through the building for another week. when talking to the owner he advised me that this building was built in the 1940's and that each recept has the potential of 240 volts if not wired properly, he says that he knows this because he first sent in his maintenance guys to do the job, but fried one of the tenants appliances and had to call a contractor in to fix the boo boo, they told him what I just stated as the reason. Any of you guys heard of this before? If so what should I be looking for when I go there? Or do you think the other contractor just gave him a line to get some work out of him? Any ideas? Thanks.

 

[hillbilly]

Re: Old Apartment Bld

Sounds like an old 208Y system to me.

 

[roger]

Re: Old Apartment Bld

Sjaniga,

each recept has the potential of 240 volts if not wired properly.

Huh?

This is true, any receptacle can be wired incorrectly and have the maximum supplied voltage present.

Hillbilly,

Sounds like an old 208Y system to me.

this is realy a HUH.

Sjaniga, it sounds as though the maintenance personel broke a "neutral" which by definition would be a "multi wire branch circuit" (edison circuit) common, and in turn caused a series across the loads of the legs or phases. The actual high voltage would not be 240v but would be a product of voltage droped across resistors in the series circuit.

Roger

 

[sjaniga]

Re: Old Apartment Bld

Well went to do the job, and get this, every recept is wired with 2 circuits with a seperated yoke, these circuits are on single pole breakers and wired with 12-3 romex, best I can tell they share neutrals. There are 2 recepts on the kitchen counter and when we pulled the old devices out we found 2 blacks, 2 whites, 2 reds, probably line and load. We thought we would use both circuits, one for each recept, but when we did that the first recept that had the red and white had 120volts and would not trip the gfci, and the second recept had the black circuit it had 240v and tripped the breaker as soon as we tested it. We ended up not using one circuit, just left it capped in the box just to get these gfci's to work properly. Any thoughts to why this was happening? Oh also we only brought the circuits to the line side of the gfci, and did nothing with the load side because we could not tell exactly where these circuits started or ended.

 

[iwire]

Re: Old Apartment Bld

You had a heads up that there was earlier trouble at this location.

when talking to the owner he advised me that this building was built in the 1940's and that each recept has the potential of 240 volts if not wired properly, he says that he knows this because he first sent in his maintenance guys to do the job, but fried one of the tenants appliances

I would not have guessed on the wiring, I would have tested it out before trying to make changes.

the first recept that had the red and white had 120volts and would not trip the gfci, and the second recept had the black circuit it had 240v and tripped the breaker as soon as we tested it.

So you had 240 from white to black and 120 from white to red?

I would not want to leave the job until I knew what was up with these readings.

[ August 23, 2003, 02:08 PM: Message edited by: iwire ]

 

[sjaniga]

Re: Old Apartment Bld

iwire, you are correct, that is why we started with a vacant apt so we could tackle this beast. This is one of those situations where you know what is happening but cant explain why. After installing the gfci's and getting the correct readings we checked every single recept and light to make sure we did not disturb anything else. I just thought that out of all the knowledge here someone might have ran into this before, becuase I havent. I am going to make up a mock situation here at the shop and see if I can duplicate what is happening, I will let you know.

 

[pierre]

Re: Old Apartment Bld

sjaniga
Did you take a look in the panel feeding this apartment to see what is connected there? I would make sure the panel is properly wired. Either that is where this situation originates, or maybe in another box where the splice is incorrect. I would be surprised if this is the method in ALL the apartments, but not shocked.

Pierre

 

[sjaniga]

Re: Old Apartment Bld

Pierre, yes we checked the panels, and they are wired with 12-3 romex, nothing out of the norm in the panels. We also checked out a couple of apartments for this and they are all wired exactly the same.

 

[goldstar]

Re: Old Apartment Bld

every recept is wired with 2 circuits with a seperated yoke, these circuits are on single pole breakers and wired with 12-3 romex, best I can tell they share neutrals.

Just for the record, if these receptacles had 2 circuits on them the breakers should have been 2 pole. However, now that you're changing them to single circuits this becomes a moot point.

Suggestion : If there are 2 receptacles at the counter, why not put one on the black circuit and one on the red.

 

[sjaniga]

Re: Old Apartment Bld

Goldstar that is a good question. The answer is, that was the first thing we did. This is when we ended up with 240v. at the second circuit (black wire) and niether circuit would trip the GFCI. What I need is a sketch to show what we did and what happened.

 

[websparky]

Re: Old Apartment Bld

Here is my guess;

In a junction box upstream of the kitchen, someone tied one of the hots to the white and at the next location you have a hot wire that is a neutral and a neutral that is a hot.

I would open all connection points between the panel and the first box to verify with an ohm meter which conductor is which. Make-up that box properly, and work your way down stream until you find the crossed wires.

 

[cselectric]

Re: Old Apartment Bld

If I understand correctly, between the Red and White wires you have 120 Volts. Between black and white wires you have 240 Volts. The first question that comes to mind is: what is the voltage between black and red? I'm going along with Websparky's logic here. My hunch is you have a red and white crossed somewhere upstream.

On another note, did you ring the wires out with an Ohmmeter? Sight unseen I won't say definitively, but it sounds as though your 3 wires (b,R,W) come into one recept, out to the other, then back out of the second recept. On that note, you may or may not be able to line load your GFI's (2 recepts per unit, 148 units. a line load config would eliminate 74 GFI's... big savings.) It should be easy to trace the wiring from point to point via simple continuity test. But I wouldn't jump on the line load bandwagon until I figured out what else the wiring fed after it left the second recept.

 

[iwire]

Re: Old Apartment Bld

As has been said check voltage between each conductor (including ground) and I would do continuity tests between dead conductors, there should be continuity between the grounding conductor and the grounded conductor.

If this kitchen had 2 circuits before and now you try to cap one off, I think you have a problem with 80.9(C) if your State adopted this part of the code, my State did not but has the same rule still.

80.9(C) Additions, Alterations, or Repairs. Additions, alterations, or repairs to any building, structure, or premises shall conform to that required of a new building without requiring the existing building to comply with all the requirements of this Code. Additions, alterations, installations, or repairs shall not cause an existing building to become unsafe or to adversely affect the performance of the building as determined by the authority having jurisdiction. Electrical wiring added to an existing service, feeder, or branch circuit shall not result in an installation that violates the provisions of the Code in force at the time the additions are made.

I think you must maintain the use of two circuits on the kitchen counters.

Bob