"(1.051) Voltages specified in this book are nominal and variations
in voltages from nominal values are acceptable within limits (83 Ill.
Admin. Code Part 410). Voltage variations measured at the
Customer's service terminal(s) shall normally not exceed for a
period longer than one minute:
a. 5.8% above or below nominal voltage for service rendered for a
lighting purpose. On the Company's 120V standard, the range of
acceptable voltage is 127 volts maximum and 113 volts
b. 10% above or below nominal voltage for service rendered for a
From 'The Information and Requirements For The Supply of Electric
Service', also known as The Rule Book.
The link is on this page from the parent company of Commonwealth
Edison, Exelon, which discusses residential power:
From the Illinois Administrative Code Index, here:
The Illinois Administrative Code, section 83-410: STANDARDS OF
SERVICE FOR PUBLIC UTILITIES & ALTERNATIVE RETAIL ELECTRIC SUPPLIERS
governs these standards, and, if satisfaction is not forthcoming
from the power company, one could bring it to the attention of
the Secretary of State, which oversees the code. Contact page:
The homepage for the Illinois Administrative Code is here:
Another Illinois power company, MIDAMERICAN ENERGY COMPANY,
has a PDF which discusses the protocol for customer complaints
related to this code, and may be useful:
Complaints concerning charges, practices, facilities or
services provided by the Company shall be investigated
promptly and thoroughly. All written complaints will be
acknowledged in writing or verbally. The Company shall
keep such records of complaints as required by 83 Ill.
Admin. Code Part 410.
If the complaint cannot be resolved at the initial inquiry
point, the information shall be promptly referred to the
employee or department who has authority to take appropriate
action to resolve the complaint. Any complaint, if unresolved
by the prior action, shall be referred to the appropriate
management employee for action.
The final step for any unresolved informal complaint shall
be a filing with the Consumer Affairs Division of the
Commission, by either the complainant or the Company, for a
resolution of the issue.
CUSTOMER CALL CENTERS:
The Company shall maintain a customer call center where
customers can reach a representative and receive current
The Company will comply with all service standards and
reporting requirements as required by 83 Ill. Admin. Code
The customer service page on the Exelon site, where you can
begin the process of communicating your problem by selecting
Residential and ComEd, is here:
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A user's guide on this topic is on skermit-ga's site, here:
Additional information may be found from further exploration
of the links provided above, as well as those resulting from
the Google searches outlined below.
Searches done, via Google:
"line voltage" standards "+/-" "Commonwealth Edison"
"83 Ill. Admin. Code Part 410"
"Illinois Administrative Code"