Michigan Residential Electrical Building Codes

In the state of Michigan, a building's electrical elements follow the Michigan Electrical Code (MEC). It, in turn, is based on the National Electrical Code (NEC). The Code, as it is called in the Great Lakes state, applies to general electrical work in residential buildings and other structures.

The Michigan Electrical Code (MEC) provides sensible safeguards for people and property from dangers arising from electric power installation and maintenance. It is based on the National Electrical Code, which covers the installation of conductors and other electrical equipment in private and public structures. It also covers conductors connecting to the electrical supply, as well as outside conductors on a property.

An individual shall not place electrical conductors or equipment in a structure or alter, change or add electrical conductors or equipment without a permit to do the work. Anyone applying for a permit must be an electrical contractor licensed by a municipality or the Michigan Electrical Administrative Board.

The Michigan Electrical Code (MEC) applies to the following:

• Electrical installation inspections.
• Construction plans, drawings and specification reviews for electrical systems.
• The alteration, construction, design, maintenance, modification and testing of electrical equipment and systems.
• Control and regulation of electrical installations at venues such as amusement parks, exhibits and trade shows, as well as other special occupancies.

The MEC applies to new electrical installations. Buildings with construction permits dated after the Code's adoption must comply with its requirements. It also covers existing electrical installations; those that do not comply with the Code's provisions can continue in use unless the installations present an imminent danger to the occupants of a building.

The authority with jurisdiction will be the chief electrical inspector or other individuals that a governing body designates. This officer shall administer and enforce the code when the use of electrical equipment or installations is found to be dangerous to life or property.

In that instance, the authority will have the electricity on the premises disconnected and place a written notice on the property listing the causes of the disconnection or condemnation, including a penalty for unlawful use within 24 hours of the problem's discovery.

It is illegal for anyone to remove the notice, reconnect the electrical supply or use electrical equipment until the issue has been remedied to the authority's satisfaction.

The chief electrical inspector or the authority with jurisdiction may also:

• Delegate other qualified people or entities to administer and enforce the Code, such as police, fire and other enforcement agencies.
• Order the removal or remedy of dangerous conditions or equipment.
• Request plans and specifications to ensure compliance.
• Require the exposure of electrical work for inspection if it has been covered or concealed.

A Code official or authority with jurisdiction has the power to enforce Code provisions. They may render interpretations of the Code and adopt their own procedures or policy to clarify its requirements. An official's interpretations, practices or policies shall comply with the Code's intents and purpose and shall not waive requirements in the Code.

The code official will retain records by:

• Retention: The authority will record all electrical inspections, including dates, violation summaries, notices serving dates, and final disposition of all violations. The authority will maintain all records until their use has been served or as the law requires.
• Availability: The authority will maintain approvals, examinations and variances, which will be available for public review during normal business hours as prescribed by law.

The authority with jurisdiction shall establish and issue permits, approvals, certificates, notices or orders of electrical safety hazards. No permit will exceed 180 days, but the authority may grant one extension of 180 days upon a permittee's presentation giving an acceptable reason for their failure to start or complete the work or activity the permit authorizes.

A permit copy shall be readily accessible or posted at the worksite or held by the permit holder.

Instead of a single permit for each installation or alteration, the authority shall issue an annual permit to an individual or company regularly employing at least one employee for the alteration, installation and maintenance of equipment on a property owned or occupied by the applicant. The MEC requires applicants to keep records of all electrical work, which they must periodically transmit to the electrical inspector.

When completing an electrical equipment installation under a permit, the person, firm or corporation installing the equipment shall notify the electrical inspector in the jurisdiction of the property.

When the inspection official finds that the installation conforms to the Code, state statutes and local ordinances, they will issue final approval. If payment has been made, they will authorize connection to the electrical supply.

If any portion of the electrical installation is hidden from view by the permanent placement of a building's parts, the party installing the equipment must notify the electrical inspector. They shall not conceal any equipment until the electrical inspector approves it. The Code official and jurisdiction are not liable for expenses incurred by replacement or removal of material to allow inspection.

A permit is not required to carry out any of these types of electrical work:

• Replacement of snap or flush switches, wall switches, lamp sockets, fuses and receptacles, and other minor repair or maintenance work.
• Replacement of lamps and utilization equipment for connection to permanently installed receptacle outlets.
• The manufacturing, repairing, servicing or testing of electrical equipment or apparatus.

A permit is also not needed for:

• Minor repairs.
• Alteration, installation, rebuilding, remodeling or repairing of dumbwaiters, elevators, escalators or man lifts carried out under a permit issued by an elevator inspection agency.
• Alteration, installation or repair of electrical equipment and wiring installed to operate audio/video signals or data transmission.
• Alteration, installation or repair of electrical equipment and wiring to generate and distribute electric current for the distribution system owned and operated by a power utility including meters.
• Alteration, installation or repair of electrical equipment and wiring to generate and distribute telephone signals for the communication systems owned or operated by a telephone company.
• Installation, servicing or maintenance of residential and commercial lawn irrigation equipment, except any permanently wired connections that are more than 30 volts.
• Installation, maintenance or servicing of landscape lighting systems and equipment, except any permanently wired connections that are more than 30 volts.

Applicants must submit detailed plans and specifications for an electrical permit and wiring or alterations if an electrical system needs installation of equipment with more than 400 amperes for the service or feeder and if a structure's floor area is more than 3,500 square feet. Electrical drawings must include:

• Lighting layouts.
• Circuits and switches.
• Raceway and conductor sizes.
• Wattage schedule.
• Riser diagram and service location.
• Load and fault current calculations.
• Proposed construction method created with symbols of a standard form.

Unless otherwise stated, all conductors are presumed to be copper. The designer's responsibility is to select disconnection and overcurrent devices for a wiring system's coordination and interrupting capacity.

When approving electrical plans, the enforcing agency does not assume responsibility for the design or deviations from the drawings. The permit holder must ensure that the plans and specifications that the enforcing agency approves – or a certified copy of them – are accessible on the job site for the enforcing agency.

The enforcing agency authorizes when an installation can be connected to the power supply. The governing utility may reconnect the electricity before the enforcing agency's approval after an electrical contractor's emergency repairs.

An electrical contractor must secure a permit after completing the work by the next business day. This requirement does not apply to upgrades, new service connections or other planned modifications.

If attached to or installed in a structure, metal piping systems that can be energized must bond to:

• Circuit grounding conductor energizing the piping system.
• Service equipment enclosure.
• Grounded conductor at the service.
• Grounding electrode conductor, if its size is sufficient.
• One or more grounding electrodes if the conductor or bonding jumper sizes are adequate. Attachment points on bonding jumpers must be accessible.

Metal piping must be bonded to corrugated stainless steel tubing (CSST). Bonding jumpers must connect to metallic pipes or fittings between a delivery point and the initial downstream CSST fitting and must not be smaller than 6 AWG copper wire or an equivalent size.

Per the MEC, type NM (Romex), type NMC and type NMS cables can be used in:

• One- and two-family dwelling units with attached or detached garages and storage buildings, as well as multifamily structures regardless of type of construction.
• In structures more than one floor above grade.
  

Cables must be hidden within floors, walls and ceilings with a thermal barrier of material that has a minimum 15-minute finish rating, according to listings of fire-rated assemblies in the Michigan Building Code.

Type NM, type NMC, and type NMS cables cannot be used in dropped, exposed or suspended ceilings other than those found in family and multifamily dwellings or commercial garages with hazardous or classified locations. They cannot be used in theaters, motion picture studios, storage battery rooms, elevators or escalators, or hoistways.

Cables cannot be embedded in poured concrete, cement or aggregate or located in hazardous or classified locations, except where expressly permitted by other articles in the MEC.