Think ''switch loop'' WHAT TO EXPECT IN THAT CEILING BOX and SWITCH BOXLAYMANS TERMS:
- SWITCHLOOP Two wires…a constant HOT and also a switched HOT…
A switch loop does not include a NEUTRAL !
The switch loop is necessary, only when the HOT [power is in the fixture box.
The ‘remarked’ white is NOT a NEUTRAL…IT IS A HOT!
A switch LEG is not a switch loop.
- OUTLET Receptacle outlet…fixture outlet…..hardwired outlet etc.
- CABLE contains more than one wire.
- WIRE A single conductor,either in a conduit or part of a cable with other wires.
- SP The usual Single Pole snap switch .
- 3WAY Control of a light fixture etc from more than one location;usually two locations.
A 3w switch is a SPDT..single pole,double throw switch.
A 120V SWITCH IS sp
A 240 SWITCH IS A DP ; DOUBLE POLE ; [2 POLE]
- HOMERUN That portion of a circuit that extends uninterupted ,from the outlet straight to its source ;usually the panel.
The first piece of information we need, is to identify where the incoming power is routed to.
Either the ceiling box ,or the wall switch box.
i.e. Fed at switch or fed at ceiling .
Many older homes ran the incoming power to the ceiling box first,and this made for a non crowded wall switch box.
We must learn what a switch loop is and what it is NOT!
The WHITE in a switch loop can NEVER bring the ‘switched’hot back up to the ceiling box.
It must always TAKE the HOT down TO the wall switch box!
This white MUST be reidentified..a.k.a 'Remarked'
I recommend remarking the WHITE in the switch loop, with a black permanent marker pen The next piece of information we need is to decide whether more than one switch controls the light .
..like a 3way control ,where we control the ceiling light from more than one location in the room.
Wiring for a 120v electrical circuit ,usually takes the form of a HOT..a NEUTRAL..and a GROUND.
Some older house wiring does not include a ground.
A HOT can be any color other than WHITE/GREY/ or GREEN.
Ground will generally be GREEN or BARE
By existing code…a NEUTRAL can only be WHITE .
Older wiring methods, like two wire Knob and Tube can be very confusing, as to which wire ,is the NEUTRAL ,with out a circuit tester and knowledge of how to identify what is which!Be careful ,as we are never permitted to switch a circuit NEUTRAL!
We must absolutely identify which wire, is the circuit HOT.
A nice non-contact circuit tester similar to this one…can easily resolve this for us ,without even touching any bare wires!read....'TESTERS'
If you discover old K& T [Knob and Tube] cloth/rubber covered wiring in any boxes ,where the insulation of BOTH wires appear to be black,and the wires themselves , are both tinned silver in appearance, the NEUTRAL and HOT wires can be identified and separated without even touching any bare wires ,if you get one of these non-contact testers which are sold in the electrical area of all DIY stores
These testers will glow, and some even make a noise when held fairly close to a HOT wire.
Remember tho,that a NEUTRAL wire ,whether white or dark old wiring, that is for some reason,disconnected upstream ,will often test as HOT because it can backfeed thru any load that is plugged in or turned on ,to get to the 120v!
It can also shock you the same as any HOT wire!
Never connect neutrals of other circuits together!
Turn the breaker back off when you are done testing...and permanently mark the neutral WHITE.
The electrical code generally requires that all habitable rooms, have at least one lighting outlet,controlled from a wall switch at the usual point of entry to that room….the rest can all be pull chain controlled; if you wish!
A wall switch controlled receptacle can also serve this purpose in all rooms other than the bathroom and kitchen.
There are basically two usual routes a 120v circuit will take to get to the required ceiling fixture or also a ceiling fan.1.The hot power from the panel is first ran to the ceiling box.2. The hot power from the panel is first brought to the wall switch box!
You can expect to find all sorts of wiring schemes to accomplish this!Route #2
is the most easy to understand as all we are doing is interupting the HOT,with a switch,before we send it on to the ceiling box.Route #1
causes the most errors and confusion, because many do not understand what a SWITCHLOOP is ,and what the WHITE wire in a switch loop is used for!
IT IS NOT A ‘NEUTRAL! a.k.a ‘common’ ..it is used as a HOT!……..and makes good economical use of the available 2 wire Romex® type cable that only contains a BLACK and a WHITE,in addition to BARE ground.
In route #1
we connect the incoming power white NEUTRAL to the fixture small white wire, or fan small white wire,but we must run the HOT down to a wall switch box .How do we get it there?
The most efficient way to do this, is with a 2 wire cable ***
that has a BLACK /a WHITE/and a GRND
We will re-color the ends of the WHITE wire,with a marker pen, to indicate that it is NOT a NEUTRAL and will use this remarked white to carry HOT down TO the wall switch.
We will use the ‘switched‘ ,BLACK HOT from the switch to carry HOT back UP to the ceiling box and will connect this BLACK, to the small BLACK or BLUE of the fan or fixture etc.*** THIS IS KNOWN AS A SWITCH LOOP.
..it has no NEUTRAL !
Just because a cable, or 2 wires ,runs between the fixture and a wall switch box,does not make it a switch loop!
The drawings shown below ,from #1 thru # 6,will show a few of the many common schemes to lite a ceiling fixture or run a ceiling fan!
The very common ‘keyless’ fixture or pull-chain fixture commonly found in basements is not covered here!..tho it is similar to any ceiling box with INCOMING POWER present ,but minus any switch loop and wall switch..
The pull-chain switch is in the fixture…NO WALL SWITCH….NO SWITCH LOOP !
GROUNDS OMITTED FOR CLARITY.
All grounds will connect together and also to the box ,if metal,and then to the fixture or fan base,and green screw of the switch ,if it has a green screw.
Any time you see two switches in a drawing here,it can be , either two switches in a 2 gang box ,or it could be two switches on a single yoke/strap.installed in a single gang box.
Incoming power to a switch box could also be via a 3way switch loop ,which will not be presented at this time! Don’t forget if you have merely incoming power to the ceiling box ,but no interconnecting cable between a ceiling box and a wall switch box, you can always install a wireless rerceiver/remote control in the fan or fixture and control them from a hand held remote and save all the trauma on installing and fishing more cable wiring!
Remember; fans require special boxes that will have tougher mounting hardware that will stand up to the weight and vibration.
This is typically #10 screws for up to 70 lbs ..fixtures use #8 screws. For up to 150lbs.Devices and faceplates usually use #6 screws.
Never use drywall screws ..they are brittle and will break.
Some of the cables shown in the drawings, are 3 conductor with ground ,for a total of 4 wires…B-W-R-BAREFind the drawing below, that you suspect may come closest to what you see, and print it out and go from there.
Ground wires have been omitted for clarity.
Typical cables are NM-B Romex® types,14-2G/14-3G or if a 20amp circuit is involved ,then 12gage. HINT:Any wall switch box that only has two wires [not counting the ground].will be part of a switch loop ,and also remember that you cannot TAP into this circuit at this box in order to supply another new fixture or receptacle outlet,as there is no NEUTRAL in this box…only a HOT and a switched HOT!
You will have the new outlet in series with the existing fixture.
That WHITE wire is a HOT COLORS:
Some older wire insulation color, fades with time and WHITE may appear as YELLOW or lite TAN.
GREEN ground may appear as BLUE!
The WHITE of a switch loop will be remarked with a color ,other than white or grey or green ...usually BLACK.
Some fans and fixtures may use the European version of colours.
Where the HOT is…….BROWN
The NEUTRAL is……BLUE
Some of the schemes are rock solid, solutions, where the light will always be controlled by the wall switch.
Others are more conservative and will also be dependent on the position of the pull switch,and usually is the result of a “MAKE-DO” retrofit!
Trying to do too much, with too little!#1
This is the very basic ....similar to converting one of those pull chain porcelain fixtures ,to a wall switch control …or a ‘KEYLESS’ porcelain fixture,that has no pull chain…….. .FEED AT CEILING and a SWITCHLOOP to single ,SP wall switch
If you are installing a FAN/LIGHT, this will permit minimal control .
The wall switch will enable the switched HOT return trip,up to the ceiling box,then you manipulate the two pull chains to get what you want!
Connect the small fan BLACK and also the small light BLUE totgether to the ceiling box, large switched hot, BLACK.
The WHITE neutral is common to both the fan and also the light.#2
This is the same as #1
but has a TAP added,that is CONSTANT HOTand NEUTRAL ,and continues off to the left ,to supply another outlet of some sort.
Remember…you cannot TAP into the switch here,because it has no NEUTRAL….a very common ERROR!
When ever you see more than one SET of wires in a ceiling box,you must determine which SET is the hot supply incoming power,and which is the switch loop ,and which merely EXTENDS power downstream to another outlet.To do this:
Turn off the breaker
Separate the wires
Turn on the breaker
Use non-contact tester to isolate the set that includes the hot of the incoming power.WHENEVER YOU SEE ONLY ONE SET OF WIRES IN A SWITCH BOX..THIS IS A SWITCH LOOP#3
This drawing is also for a single fixture ,or very conservative FAN/LIGHT control .
If you are installing a FAN/LIGHT, connect the small fan BLACK and also the small light BLUE totgether in the ceiling box, to the large switch LEG hot, BLACK.This scheme ,has no switch loop!#4
This scheme provides a CONSTANT HOT to the fan pull chain,but will always switch the light from the wall switch.
You can always depend on the light to come on with this scheme.#5
Is similar to #4 ,but has a 2 gang box with an added switch .
The two switches installed side-by-side,will give a more positive control of both the fan, and also the light fixture.The switches are depicted as they are, in the drawing ,in order to show the wiring more clearly.
HINT: You may also keep the single gang box and install a combination switch assembly where we have two switches on one single yoke-strap.#6
This has the same control as the #5 ,but the difference is that the INCOMING POWER is at the ceiling box,and we also now have a ‘SWICH LOOP’ !#7
This receptacle outlet added via a TAP from a switch loop is a very, very common wiring error.
Any appliance etc plugged into the receptacle will act as a SWITCH when turned on,and not a very good one;
With the switch ‘OFF’
The fixture light will come on DIM when the appliance is turned on ,and the appliance will not work very well…and may even burn up if a motor, like a vacuum sweeper
The fixture light will appear to work O.K. when you turn the switch ‘ON’
,with no appliance plugged into the added receptacle . ALWAYS BE ON THE LOOK OUT FOR SWITCH LOOPS..MANY ARE NOT MARKED#8
If you ever need to install a receptacle where a switch presently exists,that is on a switch loop only .
It is possible to abandon a switch loop and convert it to incoming power by removing the remarking on the WHITE wire ,and changing the wire connections around up in the ceiling box,so that the former switch loop WHITE is connected to the incoming power WHITE neutral ,and the switch loop BLACK connects to the incoming power hot BLACK,but remember that codes require “At least one wall switch controlled light fixture in each habitable room…”
All splice boxes with active wiring in them must always be accessible.BTW:
....Switch loops can also control receptacle outlets where the INCOMING POWER is at the receptacle box.
The outlet does not just have to be a fixture outlet.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>3 gang switch box
You may also use this here for some insight on how things are sometimes accomplished for more than one switch supplies/controls , several fixture runs, where the source [ 'homerun' ]is at the wall box.
The HOT supply enters from the top left .
It supplies HOT to all 3 switches .
There is even a 3way switch control thrown in ,which leads to a far 3way switch ,and onto a fixture.
Any constant 'un-switched' hot that continues on downstream....would pigtail into the hot-neutral-ground wire nuts.
Black HOTS are in one RED
White NEUTRALS are in the other RED
Cable GROUNDS are twisted together into a 'GREENIE' wire nut,then into a 'WAGO'
connector to bond the 3 switch yokes.
The ground of the supply HOT cable was left intentionally longer than the rest , so as to extend thru the 'GREENIE' .
About 12" total.
All other cable wires at least 6" excess..maybe a couple inches more...then trim to suit.
The pigtails will vary in finished length .
One has to be a bit longer to reach its switch comfortably.WIRENUT:GREENIE
(5) #14 or (4) #12...groundsRED 'WING' WIRENUT
Regular RED wirenut holds only (4) #12 or (4) #14YELLOW
...(3) #14 or (2) #123gang wall box
There are no 'switch loops'
in these pictures! hint:
Do the grounds first so they stay at the rear of the box.
Do the neutrals next and fold them towards the box rear.
Do the HOT and pigtails next and connect them to each switch.
Do the REMAINING wires of each cable to each respective switch LAST. Try and keep the wires from crisscrossing!
ernie...................................................Remember; We cannot extend any old circuit that does not include a ground!