# 2 wire service entrance conductors?



## Bigrick31 (Sep 20, 2009)

For the first time ever I saw a panel with only 2 wires coming in overhead from the utility which is just a single hot wire and a neutral. Does anyone know what this type of system this is called? Is it just a "2 wire" system or maybe half phase instead of single phase lol? 

Also I know in 2005 iirc they made it the 3 wire systems illegal and now require all panels to be fed with a 4 wire when I explained this to the general contractor I was doing a job walk with he said that the 2 wire system the house has was still legal for residential use can anyone confirm this? ive tried searching online and in my code book but I think my lack of knowledge about this type of set up is hindering my ability to research more information on it.


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## macmikeman (Jan 23, 2007)

There is a block of small shacks in downtown Honolulu (very old) that have 120 volt single phase services , and 120 volt meters. I bet that is what you got there.


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## Bigrick31 (Sep 20, 2009)

macmikeman said:


> There is a block of small shacks in downtown Honolulu (very old) that have 120 volt single phase services , and 120 volt meters. I bet that is what you got there.


This happens to be an old victorian house 3 level and they want me to completely rewire the entire house and bring it up to code. The incoming wires from the utility cant be any larger than a #6 but the existing wires going up the mast through the weather head are at best #10.

Would you happen to know is the single phase 120v setup is still legal or would we be required to bring it up to a 120/240v single phase system?


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## TOOL_5150 (Aug 27, 2007)

Thats common in some cities around here... a 120v, 30 or 60A service. The drop is still triplex, so when we rip that old crap out, and install a 100 or 200A service, we can bug the whole service in.


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## macmikeman (Jan 23, 2007)

Put in a standard three conductor single phase service, and let the poco deal with the issue of how they are going to feed it...


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## Bigrick31 (Sep 20, 2009)

TOOL_5150 said:


> Thats common in some cities around here... a 120v, 30 or 60A service. The drop is still triplex, so when we rip that old crap out, and install a 100 or 200A service, we can bug the whole service in.


This job im looking at just so happens to be in your city



macmikeman said:


> Put in a standard three conductor single phase service, and let the poco deal with the issue of how they are going to feed it...


Oh trust me that is exactly what I would like to do but of coarse the general want to pinch pennies and use as much of the old crap as possible. Im just trying to find a code section to show him we need to upgrade to the three conductor service.


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## macmikeman (Jan 23, 2007)

Bigrick31 said:


> This job im looking at just so happens to be in your city
> 
> 
> 
> Oh trust me that is exactly what I would like to do but of coarse the general want to pinch pennies and use as much of the old crap as possible. Im just trying to find a code section to show him we need to upgrade to the three conductor service.


Dig up whatever installation manual the poco puts out for your area. I will almost guarantee that there is no mention of new 120 volt services in it.
It's a poco thing, not NEC.


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## TOOL_5150 (Aug 27, 2007)

Bigrick31 said:


> This job im looking at just so happens to be in your city
> 
> 
> 
> Oh trust me that is exactly what I would like to do but of coarse the general want to pinch pennies and use as much of the old crap as possible. Im just trying to find a code section to show him we need to upgrade to the three conductor service.


Need a helper?


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## Bigrick31 (Sep 20, 2009)

macmikeman said:


> Dig up whatever installation manual the poco puts out for your area. I will almost guarantee that there is no mention of new 120 volt services in it.
> It's a poco thing, not NEC.



Ahh that makes sense! Ok ill dig that up thanks for all your help!


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## Bigrick31 (Sep 20, 2009)

TOOL_5150 said:


> Need a helper?


I've already got myself and another journeyman ready to do the job I think 3 people would be a little much but if the other journeyman for whatever reason decides he dosnt want to do the job or dosnt have the time I'll le you know.


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## TOOL_5150 (Aug 27, 2007)

Bigrick31 said:


> I've already got myself and another journeyman ready to do the job I think 3 people would be a little much but if the other journeyman for whatever reason decides he dosnt want to do the job or dosnt have the time I'll le you know.


Sounds good. if you ever need a hand just send me a PM on here, im a general certified electrician.:thumbsup:


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## mbednarik (Oct 10, 2011)

show him art 220. I don't think a 3 story home is going to run off of a 30 amp 120v service.


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## Dennis Alwon (May 9, 2009)

If you mess with the service you need to deal with art. 230.79 and 230.42(A) & (B)


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## MDShunk (Jan 7, 2007)

I still occasionally run across old 2-wire, 120 volt, 30 amp services. They're getting more and more rare. It's normally on a small one or two bedroom house, with one circuit for the kitchen, and one circuit for the rest of the house. Sometimes, one circuit for the first floor, and one circuit for the second floor. More often than not, the triplex has been changed already to modern 3-wire, and the extra hot is taped off at the point of attachment. 

The worst cases are old apartment buildings, that are actually served with 240 volts, but each apartment meter is tapped off every-other hot leg, with 120 volt meters. There's not much you can do on these upgrades but start over from scratch. 

I've gotten caught with my pants down a time or two, when called to add a new 240 volt load to an occupancy served with a 120v service. The last one I remember was a 240 volt window-type air conditioner. I took a bath on that one, since I gave a firm price, and pretty much had to stick to it. They got a quick and dirty service upgrade for the cost of adding an air conditioner receptacle. I always try to remember to look at the meter now to see if it says "120v" on it, or look at the panel a bit more closely.


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## retiredsparktech (Mar 8, 2011)

macmikeman said:


> Dig up whatever installation manual the poco puts out for your area. I will almost guarantee that there is no mention of new 120 volt services in it.
> It's a poco thing, not NEC.


There's very little mentioned about 120V 2 wire services in our metering manual. It's mainly used for sign lighting and cable TV amplifier sites. 
IIRC, the minimum services for residential installations since the 1959 code has been 100 amp 120/240 3 wire services.


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## Shockdoc (Mar 4, 2010)

I just left a house in Queens NY getting upgraded from 40 amp 120 volts. Three 30 amp fuses protecting the original three #14 BX circuits. It's all getting rewired. Still common in some old homes with little old ladies living there.


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## Shockdoc (Mar 4, 2010)

retiredsparktech said:


> There's very little mentioned about 120V 2 wire services in our metering manual. It's mainly used for sign lighting and cable TV amplifier sites.
> IIRC, the minimum services for residential installations since the 1959 code has been 100 amp 120/240 3 wire services.


100 amp i believe has been the minimum since the 80's. I've come across many 60 amp services from the 60's.


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## MDShunk (Jan 7, 2007)

Shockdoc said:


> 100 amp i believe has been the minimum since the 80's. I've come across many 60 amp services from the 60's.


For a dwelling, yes, but it's still legal to serve a "dwelling unit" with less than a 100 amp service. Common in apartment buildings. As mentioned, things like billboards, catv amps, and site lighting services are often 30 amps services. It's almost impossible, however, to get a new 30 amp service metered at 120 volts. If you're putting in a small service, it will be a 240 volt service.


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## cortez (Oct 23, 2011)

I have see these on older single family units, especially very small single story bungalows. Like mentioned above only two circuits/Edison fuses (usually two 15 amp ones). The wire to the pole can be as small as 14 gauge, strung in parallel. 

They sure did make some good wire back then as the insulation is often still intact withstanding the sun ect.

Older folks on social security often only use their appliances so as to not blow any fuses (disconnecting the fridge to iron ect.). 

These houses are so small it is easy to rewire and upgrade (new service in basement and new circuits going up directly for outlets or down for lights and switches from attic which minimize plaster repair).


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