Is Romex Legal In Illinois?

Dennis Howard
by Dennis Howard

So, you live in Illinois, and you are updating or remodeling your home. As you begin the demolition, you immediately find that all the electrical wiring inside the walls is metallic conduit.

Immediately you begin to ask questions. Can you run Romex in Illinois?

According to the National Electrical Code, Romex is acceptable for branch circuit wiring in residential and commercial applications. However, local building codes don’t necessarily mirror the NEC. The most notable exception to the NEC acceptance of Romex is the Chicago, Illinois area. Chicago’s building code requires metallic conduit in all structures. Many suburbs of Chicago have adopted the same regulations.

Despite the National Electrical Codes’ acceptance of Romex for branch circuit wiring, your local building code may differ. Nothing prohibits a local jurisdiction having authority from enacting or approving building codes that are different or more stringent than the accepted national codes. We always recommend that before you start any remodel project, you discuss your plans with local building officials to ensure that you are within code on your project.

Do You Need Electricial Wiring or Panel Upgrade Services?

Get free, zero-commitment quotes from pro contractors near you.

Where in Illinois is Romex Legal?

According to the Illinois State Government website, the State of Illinois has not adopted a state-wide building or electrical code. Counties and cities in Illinois adopt and modify building and electrical codes for their jurisdiction. The operative terms here are “jurisdiction having authority.”

Identifying and listing every county and incorporated city in Illinois is far beyond the scope of this article. The easiest way to know if Romex is an approved wire is to contact the building authorities in the county or city in which you live.

However, we know that the Chicago electrical code requires all electrical installations to be run in conduit. Most cities and counties around the Chicago metro area mirror the Chicago electrical codes. This means that even residential electrical installations must be run using metallic conduits.

If the NEC approves Romex, Why is Chicago Different

There is a lot of mystery and conjecture about why Chicago adopted such stringent requirements in their electrical code. A search of the internet returns several interesting theories about why Chicago’s electrical code doesn’t allow the use of Romex.

The Great Chicago Fire

In the late 1800s, Chicago was one of the most vibrant and rapidly growing cities in the midwest. Many historians point to Chicago as the economic hub of the expanding growth in the central and western parts of the United States. Chicago developed into a modern city whose leaders were focused on keeping Chicago on the cutting edge.

Then, in 1871, a destroyed much of Chicago’s residential and commercial infrastructure. Rebuilding began almost immediately, but not before Chicago city leaders were determined to institute changes to their urban planning to ensure the safety of their city. Many progressive changes to Chicago’s building codes and urban design to facilitate these new ideas. Among those changes were:

  • Wider streets to ease congestion and make emergency responses faster
  • Enclosed fireproof stairwells in multi-story buildings
  • Outward opening fire exits and clearly marked escape routes.
  • The installation of firewalls in large commercial structures
  • The use of fireproof materials in many construction projects.

As time moved forward, Chicago continued to tweak the building and electrical codes as new technologies and new materials began to be used in the construction trades. Eventually, this led to the adoption in 2017 of an amendment to the electrical code requiring metallic conduits in all residential structural wiring.

Union and Industry Involvement

Some observers of the Chicago building code situation contend that the trade unions and some industries may contribute to the move toward the requirements for metallic conduit in all construction. There may be some merit to these arguments.

There is no doubt that installing residential wiring in conduit is more labor-intensive and more expensive than Romex installations. From an economic standpoint, the extra labor involved benefits the union electricians. Chicago has a long history of strong trade unions, and their power in the area is not to be dismissed.

Some parties also claim that the vendors of metallic conduit staunchly supported the change to the Chicago electrical codes anticipating a surge in sales of metallic conduit and fittings. Whether these allegations are true remains to be proven.

Is Metallic Conduit in Residential Structures Safer?

The National Fire Incident Reporting System is a nationwide data gathering operation run by the US Fire Administration. Every fire department in the US reports any fire-related incident to the NFIRS system. The collected data is analyzed to discover dangerous trends or situations.

Data from NFIRS was used to look at residential structure fires in Illinois that mirror the more stringent electrical codes in Chicago. These areas have reported fewer electrically initiated fires in residential structures than other parts of the US since the requirement for metallic cable to be used in residential structures.

Based on this data, it is possible to conclude that using metallic conduit in residential structures results in a safer electrical environment. It is hard to say whether this decrease in residential electrical fires is directly related to the use of metallic conduit or to other factors

Is ROMEX Safe?

The National Electrical Code approves the use of Romex in most residential structure wiring systems. The use of Romex in these situations is restricted to branch circuits in the home running from the service entrance box where the main disconnect and circuit breakers are located.

By and large, most residential structures constructed in the United States in the last 40 or 50 years are wired with Romex. Romex has proven safe when installed properly. Experts say that the Romex wiring in these homes should last another 50 years without problems.

Based on the history of Romex use in residential wiring, it can safely be said that Romex is safe. It is hard to imagine that the National Electrical Codes would approve non-metallic cables for most residential applications if there were any safety questions.

What are the Advantages of Running Conduit in a Residential Structure?

Electricians and fire safety professionals note several reasons that running electrical branch services in conduit is safer than running Romex. Most of these issues center around protecting the conduction cable from damage when the wire is hidden in a wood stud framed wall. Some of the more common reasons given include the following.

Protection of Wires from Damage

One of the greatest dangers to electrical wiring that runs through stud walls is damage from penetrations of the wall itself. Romex wire can be easily penetrated and damaged by nails or screws. Homeowners may inadvertently penetrate the Romex when making alterations or additions to their homes.

This damage can result in short circuits that can cause fires within the confined space of the wall. These fires are often hidden and can extend quickly throughout the structure, causing major damage before being discovered.,

Rodent Damage

There are reports of rodent damage to Romex wire in some areas. Mice and rats especially will chew on almost anything. Damage to the PVC sheathing or the wires’ internal insulation can lead to short circuits or other problems with the wiring system.

Wire run through conduit is much more rodent resistant than Romex. Conduit-protected electrical wiring is almost impervious to rodent damage. This can be a distinct advantage, especially in rural areas or in urban situations where rodent populations are high.

Remodeling or Electrical Additions

When remodeling a home wired with Romex, adding additional branch wiring, outlets, or light fixtures requires removing the wall coverings to access and change the wire runs. With conduit, it is often possible to pull additional wire through an existing conduit to add branch circuits. Additional outlets and lighting can be installed by removing only small sections of wall covering to access the conduit.

How is Conduit Installed in a Wood Stud Wall?

Depending on the building and electrical code, there are two viable options for installing conduit runs in a wood stud wall. Both may be acceptable, but you should consult with the building inspection department to ensure that your installation meets code requirements.

Notching for Conduit Runs

Some building codes allow the wood stud to be notched to accept the conduit run where necessary. The notches must be only large enough to allow the conduit to fit flush with the back of the wall covering. This is to ensure that the structural integrity of the wood studs is not compromised.

In addition, some building codes require that a metal strap be pinned in place across the notch once the conduit is installed. Your electrical contractor will be versed in the requirements needed to meet the requisite codes. If you are doing the work yourself, be sure to check with the building codes office for the current standards.

Running Conduit Through Holes in the Wood Studs

Many electricians report that they successfully run the electrical conduit through holes in the studs like Romex. There are some tricks to making these kinds of conduit runs. Some electrical contractors offer these ideas.

  • Use a door opening or an interior corner to feed the conduit into the stud space. When the wall coverings are applied, they will hide the extra holes driller to allow access.
  • Cut the conduit into shorter sections that can be worked into the holes in the studs more easily and without compromising the conduit. This requires more work and more fittings but allows conduit installation in tight situations.
  • If the electrical code permits, consider using flexible metallic cable in your installation. Some codes allow only short runs of flexible cable. However, this can make the installation easier under some circumstances.

Do You Need Electricial Wiring or Panel Upgrade Services?

Get free, zero-commitment quotes from pro contractors near you.

Illinois and the Question of Romex Wiring

Many locals in Illinois allow Romex to be used for branch circuit wiring in residential applications. However, in the Chicago area, many electrical codes mirror that adopted by the City of Chicago. These codes require metallic conduit for all electrical installations ruling out the use of Romex.

Dennis Howard
Dennis Howard

Dennis is a retired firefighter with an extensive background in construction, home improvement, and remodeling. He worked in the trades part-time while serving as an active firefighter. On his retirement, he started a remodeling and home repair business, which he ran for several years.

More by Dennis Howard