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A/C Power From the Pole to the House

67.171.173.158
Posted on August 11, 2012 at 17:01:10
The Dill
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Posts: 245
Location: Portland, Oregon
Joined: July 1, 2004
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  Since: December 0, 0000



I saw this today and it got me thinking. Why is the wire size smaller from the pole to the house and then coupled to a larger wire going to the fuse box. One would think the opposite would be true. (not my home)

Any opinions?

 

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Your A/C provider is a cheap tightwad? Also.., posted on August 11, 2012 at 18:03:54
Elizabeth
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Posts: 10070
Location: Great Lakes Region
Joined: December 20, 2000
 The wire from the provider is in open air. And thus is cooled directly by the air.
The wires into the home are in contact with an enclosed tube, and need to run cooler. Size matters. The bigger wires will not get as hot.
The outside wires does not matter.
That is another total guess..

 

RE: A/C Power From the Pole to the House, posted on August 12, 2012 at 05:06:38
jimmyjames
Audiophile

Posts: 4234
Location: Raleighwood
Joined: February 20, 2001
 the power company typically stops their wire at the meter (base) and not the service head as shown in the picture. They do not have to be in compliance with NFPA/NEC code. The load side wire to the house from the meter to the house main does have to meet code. The power company bases all their calcs for wire and transformer sizing based on load "diversity". Which really means (approximatley for this exercise) that 99% of the time they believe your house will only draw 10% of the rated mains current. Don't ask me how their wire does not melt the insulation on a 100 degree day when you are running your air conditioning as hard as it will go, cooking dinner on the electric range while washing and drying clothes, every light in the house on and someone is taking a shower making the hot water heater run.

Sometimes the power company's wire insulation does melt and the wire burns into. Happened to the owner of the company I used to work for who lived in a mansion with six 5 ton heat pumps. They went on ski vacation for 2 weeks in the winter. Came home to a cold (mansion)because they had set the thermostats back via their central home automation system. They turned on all six heat pumps and heat strips in the air handlers via the home automation system and the power company wire coming into the house promptly melted and burned into where it turned up into the CT cabinet from underground. I got called out to meet the power company with 6" of snow on the ground. They had to trench in thru the snow, a new (bigger) line to the house that morning. The existing wire that burned coming into the house was no bigger around than your pinky finger. That for a 9000 sq.ft. house (mansion).

 

Your guess is the correct answer. nt, posted on August 12, 2012 at 06:39:37
Jerry P
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Posts: 760
Location: NE Ohio
Joined: June 17, 2000
 nt

 

RE: A/C Power From the Pole to the House, posted on August 12, 2012 at 07:26:32
jea48
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Posts: 6036
Location: Midwest
Joined: January 5, 2005
Contributor
  Since: January 6, 2005
 the power company typically stops their wire at the meter (base) and not the service head as shown in the picture.

Underground fed service in most cases yes.

Overhead service to a house, no.... At least here in the Midwest.

The electrician installs everything from the weatherhead to the electrical panel.

The service of the picture the OP supplied was installed and wired by an electrician. The utility company made the connection to the weatherhead conductors.

From the looks of the picture I would date the install from the 50s maybe early 60s.

 

RE: A/C Power From the Pole to the House, posted on August 14, 2012 at 17:01:47
jea48
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Location: Midwest
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  Since: January 6, 2005
 Looking at your service I would guess it was installed in the 1950s maybe early 60s.

Back then there wasn't many high current usage items like we have today.
I can't recall anybody that had central A/C.


I built a new house in 2007. The 200 amp service is fed underground.
I used 3/0 copper from the meter socket to the panel.

The utility company ran 4/0 USE aluminum to the line side of the meter socket.

Power companies do not have to follow NEC code but they are still regulated by the states and follow utility power codes.
Power companies have increased the size of their transformers as well as the size of the power line to the house because of the ever growing demand placed on them.
>>>>>>>>>>>>>>>

Looking at the picture you supplied of your electrical service I do see a problem. A drip loop was not left when the power company made the hook up to the service mast. The connections should be below the weatherhead. Yours are above.

The drip loop stops rain water from running down the outside of the conductors as well as between the insulation and the wire of the conductors.

I would bet rain water has been running into the weaterhead down the mast conduit as well between the insulation and wire into the weatherhead into the meter socket/enclosure and more than likely into the electrical panel.

If you feel comfortable pulling the panel cover you could check for rust and corrosion inside.....
Jim


 

RE: Your guess is the correct answer. nt, posted on August 14, 2012 at 17:10:47
6bq5
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Posts: 595
Location: SF Bay
Joined: August 16, 2001
Contributor
  Since: September 14, 2012
 Yes,
Wire in free air can be smaller than wire in conduit, walls or underground.
Except for the example of the multiple large heat pumps all going on simultaneously - you should not need to worry about the connection.

Happy Listening

 

RE: A/C Power From the Pole to the House, posted on August 14, 2012 at 21:19:04
The Dill
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Posts: 245
Location: Portland, Oregon
Joined: July 1, 2004
Contributor
  Since: December 0, 0000
 As said, in my original post "it is not my home"

 

LOL, my bad..... nt., posted on August 15, 2012 at 06:24:04
jea48
Audiophile

Posts: 6036
Location: Midwest
Joined: January 5, 2005
Contributor
  Since: January 6, 2005
 //

 

RE: Your guess is the correct answer. nt, posted on August 15, 2012 at 06:39:39
jea48
Audiophile

Posts: 6036
Location: Midwest
Joined: January 5, 2005
Contributor
  Since: January 6, 2005
 NEC 2011, Table 310.60(C)(68)
Ampacities of insulated single aluminum conductor cables Triplexed in air based on conductor temperature of 90*C (194*F) and 105*C (221*F) and ambient air temp of 40*C (104*F).
#8) 50 amps
#6) 70
#4) 90
#2) 125
#1) 145
#1/0) 170
#2/0) 195
and so on.

Note.
Refer to 310.60(C)(4) for the ampacity correction factors where the ambient air temperature is other than 40*C (104*F).

So in States where the ambient air temp is know to get higer than 40*C (104*F) the Ampacity rating of the AL wire is adjusted down.

 

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