Wiring

 

 

 

Here are a few typical guidelines that apply to residential work. These are NOT legal interpretations of any one code, so check with your local authority before starting work.

Kitchens
All kitchen, breafast room, pantry and dining room outlets must be supplied by at least two 20-amp small appliance circuits.
Outlets above the kitchen counter (used by countertop appliances) normally are fed by both circuits – they all cannot be wired to just one circuit. The circuits should not supply any lights or other outlets in the house.

Appliances
Separate circuits are needed for built-in appliances (i.e. oven, range, disposer, dishwasher, central air conditioner, furnance).
One 20-amp circuit is needed for laundry outlet within 6` of the machines. An electric dryer requires an additional 240-volt circuit.

Outlets
One lighting/convenience outlet circuit should be provided for every 575 square feet of floor space in a house.
Any bathroom or garage outlet within 6` of a sink must be Ground-Fault Circuit interrupter (GFCI) protected. All kitchen outlets for countertop must be GFCI protected. Bedroom outlets should be Arc-Fault Circuit Interrupter (AFCI) protected.
At least one GFCI outlet is required in an unfinished basement, as well as most outdoor outlets. Exceptions include inaccessible outlets like those in a garage ceiling or behind a refrigerator.
Any point along the bottom of a wall (which is 2` or wider) must be within 6` of an outlet. The 6` distance cannot be measured across a doorway or fireplace. And the outlet must be within 5 1/2` of the floor. (This cuts down on extension cord use, especially across doorways, fireplaces and similar openings.)

Switches
Every habitable room, hallway, stairway or garage must have a light switch that controls lighting in that area. In kitchens and bathrooms, the light switch must control a pearmanently instaled light fixture. In other rooms, the switch can control either a light fixture (in the ceiling, for example) or a receptacle into which a lamp may be plugged.

Rough-in Electrical

In a new house, addition or major remodeling project, cable and boxes are “roughed-in” before the walls are insulated and drywalled.

NOTE: Insulation can be put up then removed for an inspection, but inspection must be done before the walls are sealed by a vapor barrier and wallboard.

– Locate/place/attach all device and junction boxes for outlets, lights and switches.
– Make sure wall switches are located with proper respect to door swing, and wall outlets will not conflict with tile, cabinets, lockers, casework, or baseboard heating.
– Each box should stick out a little past the framing so its front will be flush with – or set back just a fraction from – the drywall.
– You can use a scrap piece of drywall to set boxes out the right distance. Some boxes even have a pre-formed 1/2″ reference line for quick installation.

– Drill or notch the framing to allow for the cable/wiring to run between boxes, down into the under-floor crawl spaces, up into the ceiling, as well as through studs. (Most rooms have either an attic above or a basement/crawlspace below. Drill holes so cable runs horizontally through joists.)
– A heavy-duty right-angle drill with a 1″ bit is the tool for this job. wall holes drilled at about knee-height will be just right for outlets. Holes through ceiling joists and wall plates will be a bit harder; that’s where the right-angle drill comes in really handy.

– Run wire/cable/conduit from the service panel to each box and between boxes. (See “Pulling Cable,” inside.)

– Pull wire/cabel into each box; clip, clamp and cap.

– Use metal reinforcing plates (nailing plates) at all points where the drilled hole is than 1 1/2″ from either outside edge of a stud or joist. Nailing plates are required over all notches.

Cable Checklist

– Cabling must be installed and supported properly. It also must be protected from physical damage and from electrical damage.
– Bends in Romex must not be made too sharply. Bending cable incorrectly can weaken the outer sheathing as well as the insulation on the individual conductors. The radius of the curve of the inned edge of any bend must not be less than five times the diameter of the cable. A correct installation will result in a “jug handle”.
– Cable must be fastened the the framing every 4-1/2 feet, using staples, cable ties, straps, hangers, or similar fittings.
– Flat cables (e.g., 14/2 Romex or 12/2 Romex) must not be stapled on edge.
– Flat cables mmay be installed on top of one another and fastened with one staple, so long as one flat side is against the flat side of the next cable. (Two cables should not be placed side-by-side and fastened with one staple; this can damage the cable insulation.)
– Check that staples or fasteners do not cut through a cable’s insulation.
– Where cable runs through wood framing members, it must be no closer than 1-1/4 inches to the nearest edge of the framing member. When this clearance cannot be maintained, a nailing plate must be added for protection. In cases where a framing member is notchet to accommodate electrical cabling, a nailing plate is always required.
– where cable runs through metal studs, plastic grommets must be inserted in all holes, whether those holes are manufactured or field-drilled. The plastic grommet must cover all metal edges of the hole, to provide physical protection as the cables are pulled through the metal studs.
– Openings around penetrations through walls, floors, and ceilings must be filled with an approved fire-stopping material. (Some locales require fire-stopping measures in both non-fire-rated and fire-rated building components.)
– Check for draft-stopping measures where cabling penetrates framing members.
– Cabling must be secured within 8″ of every nonmetallic box that’s smaller than 2 1/4″ x 4″.
– Cabling must be secure within 12″ of every nonmetallic box that’s larger than 2 1/4″ x 4″.
– Cabling for recessed lights should be fastened to the nearest framing, providing a jug handle.
– All cables that run into metal or plastic boxes must be protected from abrasion. This can be accomplished by using connectors that have smooth openings for the cabling to go through or by simply making sure a short section of the cable sheathing extends past the clamping mechanism of cable clamp.
– All cables that run into metal or plastic boxes must be secured to the boxes. Commonly, this is done using internal or external clamps.
– Acoount for the voltage drop that can be caused by long runs of cable. Try to limit drop to less than 3%.
– Separate runs of cable/wire are required for bedroom outlets (so they can be provided with Arc-Failure Circuit Interrupter (AFCI) protection. The same is true for any other circuits requiring AFCI or GFCI protection.

Pulling Cable

“Running cable”or “pulling cable” is a bit more involved that it sounds. Getting cable to cooperate can be frustrating and time consuming. So it helps to be patient… and a bit creative.

Double-check your circuit diagrams before running any cable. Also make a not where you can double-up runs anywhere by pulling two cables at once.

When pulling wire through conduit, or even when pulling nonmetallic-sheathed cable through holes in studs, joists, etc., “fish tape” can be fed through holes, hooked to the cable or wire, and pulled back to retrieve it.

A typical way to pull cable is to start at the last fixture in the run, pull cable to each fixture in the circuit, and continue all the way back to the service panel:
– Leave the box/spool of cable at the fixture you are cabling, unwind enough cable to complete the run, and then start pulling it through the holes. On long runs, you may need to return to the box or spool a few times to feed more cable through. Two people can really save time: one feeding cable and one pulling cable.
– Nonmetallic-sheathed cable can tangle or bind. If you feel resistance while pulling, tha cable is probably kinked somewhere along the run and should be straightened out.
– Each time you reach a junction box, pull a few extra feet of cable through for making connections later.
– Once the cable reaches the service panel, leave a foot or so of extra length on both the service end and the box/spool end for connecting.
– After the cable is in place, fasten it framing with staples every 4′-6″, at turns, and within 12″ of where cable enters a box. At turns, provide a jug handle.
– Label each cable at the panel end with a felt pen or piece of tape to keep them organized.

Next Steps: Attach the cable to the framing and securing the cable junction/device boxes with clamps provided within the boxes.