Service Entrance Amperage?

[Joe Funderburk, CMI]

Nothing confuses me more than trying to determine amperage when no main breaker exists. Can somone please help with the following?

1) What are the service entrance wire sizes (CU and AL) with their appropriate amperage capacities?

2) How do you determine conductor wire size when you can't read it on the conductor?

I did a 24 year old house yesterday--what would you say the amperage is based on the photo of the conductor feeding into the panel (photo of panel and service entrance conductor sheathing attached)? (I could not read the rating of the panel itself--hidden behind wires.)

Thanks for the help.

[Jae Williams]

Many electrical supply companies have a plastic gauge for this purpose...

[lewens]

1/0 al can carry 100 to 125 amps so I would assume 100 amp service.
I know assume means make an *** of you and me.
Larry

[Michael R. Boyett]

Are you sure Jae? I've been looking for one for a long, long time and have yet to find one. Please let me know where to get one. I've been told that you can't measure the outside diameter of the insulation to determine the gauge, i.e. you must measure the wire itself. That would be difficult even with a plastic gauge I think.

[Greg Fretwell]

This is for the service entrance or MAIN FEEDER to the home, not sub panels
from 310.15(B)(6)
I give up, it won't let you type a table

[Roy D. Cooke, Sr]

Originally Posted by mboyett

Are you sure Jae? I've been looking for one for a long, long time and have yet to find one. Please let me know where to get one. I've been told that you can't measure the outside diameter of the insulation to determine the gauge, i.e. you must measure the wire itself. That would be difficult even with a plastic gauge I think.

I had a burndy servit one made out of brass and it had two guage lines one for wire and onw with the insulation . .Now with the different thickness of the insulations have no idea how close it would be . ( misplaced it 30 years ago still keep looking )
Roy Cooke sr . RHI. Royshomeinspection.com. CAHPI-ON

[Joe Funderburk, CMI]

I ordered a guage yesterday from Professional Equipment (item E835): $13.95. But I obviously didn't have one during this inspection. Some of you guys seem to be able to "eyeball it" but I certainly can't.

[Joe Funderburk, CMI]

Would some Guru please post the wire sizes in CU and AL and the appropriate amperage? I'll buy you a beer for doing so.

[Joe Funderburk, CMI]

Also, does anyone make a special comment when the service is only 100 amps? I have been doing so (telling them to talk to a sparkie about the limitations of a 100 amp service). Wondering if that is what most do?

[Larry D. Kage]

here's one:

[Larry D. Kage]

And another:

[Joe Funderburk, CMI]

I owe you Larry. Thanks so much.

What is "THW", "THWN", & "TW" insulation? Anyone?

[Michael Larson]

Originally Posted by jfunderburk

I owe you Larry. Thanks so much.

What is "THW", "THWN", & "TW" insulation? Anyone?

Some reading for you to enjoy.
There is meaning in the letter sequences used to identify conductor
types, and these letters usually refer to properties of the conductor's
insulating layer(s). Some of these letters symbolize individual
properties of the wire while others are simply abbreviations. For
example, the letter "T" by itself means "thermoplastic" as an
insulation material, as in "TW" or "THHN." However, the three-letter
combination "MTW" is an abbreviation for Machine Tool Wire, a type of wire whose insulation is made to be flexible for use in machines experiencing significant motion or vibration.
INSULATION MATERIAL

===================
C = Cotton
FEP = Fluorinated Ethylene Propylene
MI = Mineral (magnesium oxide)
PFA = Perfluoroalkoxy
R = Rubber (sometimes Neoprene)
S = Silicone "rubber"
SA = Silicone-asbestos
T = Thermoplastic
TA = Thermoplastic-asbestos
TFE = Polytetrafluoroethylene ("Teflon")
X = Cross-linked synthetic polymer
Z = Modified ethylene tetrafluoroethylene
HEAT RATING
===========
H = 75 degrees Celsius
HH = 90 degrees Celsius


OUTER COVERING ("JACKET")
=========================
N = Nylon


SPECIAL SERVICE CONDITIONS
==========================
U = Underground
W = Wet
-2 = 90 degrees Celsius and wet

Therefore, a "THWN" conductor has Thermoplastic insulation, is Heat resistant to 75o Celsius, is rated for Wet conditions, and comes with a Nylon outer jacketing.
Letter codes like these are only used for general-purpose wires such as those used in households and businesses. For high-power applications and/or severe service conditions, the complexity of conductor technology defies classification according to a few letter codes. Overhead power line conductors are typically bare metal, suspended from towers by glass, porcelain, or ceramic mounts known as insulators. Even so, the actual construction of the wire to withstand physical forces both static (dead weight) and dynamic (wind) loading can be complex, with multiple layers and different types of metals wound together to form a single conductor. Large, underground power conductors are sometimes insulated by paper, then enclosed in a steel pipe filled with pressurized nitrogen or oil to prevent water intrusion. Such conductors require support equipment to maintain fluid pressure throughout the pipe.

[Joe Funderburk, CMI]

You wowed me, Michael. Thanks a lot!

[Michael R. Boyett]

Originally Posted by jfunderburk

I ordered a guage yesterday from Professional Equipment (item E835): $13.95.

Well, that's a really neat gauge but not what I'm looking for. More often than not, the service entrance wires are separated already and come to the SE panel individually thru a short piece of conduit. This gauge only works for 3 conductors still in the outer jacket. I think I'll order one anyway.
Attachment 4132