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The “New” Aluminum Wiring
When a home inspector hears the words “Aluminum branch circuit wiring in
solid conductor sizes 14. 12. or 10 AWG”, we usually cringe. Everyone is aware
of the fires associated with certain types of Aluminum wiring. In the late
1960’s until the mid 1970’s aluminum was used to wire entire houses. This was
mostly due to the high price of copper. Receptacles, switches and electrical
devices were not designed with the specific properties and requirements of
aluminum. The terminations at these devices, over time began to fail due to
improper connection type and dissimilar metal corrosion. The connections between
the steel screws and aluminum wire became loose due to the heating and cooling
(load cycling) of the circuit. Also something know as “creep”, which is a
property of all metals. Creep is the measurement of the rate of change of a
materials dimension over a period of time when exposed to a force at a
particular temperature. Old aluminum wire had a higher creep rate than copper.
The difference in creep rate between the steel screws and aluminum resulted in
overheated connection failures, that in some cases caused fires. Devices labeled
CU/AL were manufactured and were supposed to address this problem; however they
did not and were replaced with devices labeled CU/ALR (copper-aluminum,
Revised). These devices have screw terminals that have deeper undercuts and use
an alloy that closely mimics the characteristics of aluminum. The CU/ALR
designation is for branch circuits. CU/AL is still used for large conductors
including main service conductors. Most home inspectors report any solid core
aluminum branch circuits in sizes 14, 12, and 10 AWG as a potential defect.
Recently, The American Society of Home Inspectors (ASHI) has removed the
requirement to describe solid conductor aluminum wiring because, according to
ASHI it is inconsistent with other SOP sections, in that the existing
requirement singles out a specific component for special reporting and simply
notifying the client about the presence can create concern where none should
exist. Many home inspectors do not agree with this.
So what about the “new aluminum”, and how can we tell the difference, and
properly advise our clients?
Metallurgists developed an
aluminum alloy that possesses different characteristics from the “old” aluminum
and more closely resembles the characteristics of copper. So what should a home
inspector be looking for when they see aluminum wiring, and how should they
advise their client:
If you see aluminum branch circuit wire (like
copper wire) it should be identified in your report
·
14 AWG aluminum branch circuit wire is not
recommended
·
12, and 10 AWG aluminum branch circuit wire
should be stamped with the following: AA-8000, AA-8176, or AA-8_ _ _ (followed by
3 other digits)
·
AA-8000 is “compact stranded” as can be seen
from the photo at the beginning of the article, not solid core.
·
If you see AA-1350 – this is the old style
aluminum wire and should be reported as a potential fire hazard if improper
connections exist.
·
Receptacles and switches marked CU/ALR should be
used with smaller sized aluminum branch circuit wiring
·
Larger conductors including main service
conductors should be connected to devices labeled CU/AL
·
Any arcing, scorching, or loose connections should
be reported
Although some organizations do
not require home inspectors to report on aluminum branch circuits, many do. New
York State Home Inspector Standards of Practice Section 197-5.9; Electrical
System (b) (3) state: “Home inspections shall describe readily accessible and
observable portions of: 3. The presence of aluminum branch circuit wiring”.
It would be impossible to trace all the
aluminum branch circuit wiring to ensure proper connections, and devices were
used. It is my belief that your client should be advised to have a licensed
electrician examine the aluminum branch circuits and terminations to ensure
proper connections have been made and a fire hazard does not exist.
Here is NEC table 310.16 that
details specific types of conductors and allowable ampacities.
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