Wiring question

[trader4]

Wrong. Go take a look at how a GFCI is actually designed. As I stated, besides comparing the current flowing in the hot and neutral through any loads, they also generate a small 120hz test voltage on both the hot and neutral. Any path back to that GFCI other than the hot and neutral connected to it will result in it tripping. That path could be the neutral of that circuit connected to ground OR that neutral connected to another neutral. In either case, the GFCI will trip as soon as power is turned on, without any load.

So, if you want to find out if you have any shared or crossed neutrals, all you have to do is replace breakers one at a time with a GFCI and turn the power on. If there are any crossed or shared, the GFCI will trip. It's all about parallel circuits.

You really should stop giving advice on subjects beyond your pay grade.

[bud--]

Requires a load at each outlet.

If neutrals from different circuits are interconnected, the GFCI feature trader describes would cause an immediate trip. The feature is intended to detect downstream N-G connections and a N-otherN connection looks the same.

If the circuit is connected to a different neutral, when a load is connected the neutral and hot current at the GFCI breaker will be different and the GFCI will trip.

For a different neutral the trip will be when there is a load connected, not immediate.

The injected current on the hot wire doesn't accomplish anything since there is voltage on the hot wire anyway. If the GFCI is reverse H-N wired the feature that detects a N-G (or N-otherN) connection downstream will still work.

I can't think of an easier test than GFCI breakers. You need to stick a load on each outlet.

You could also loop a clamp on ammeter around both H and N for the circuit. It would also require a connected load, one outlet at a time.

There isn't a real easy test for N-N connection and interchanged neutrals.

Sure seems that way some days.

------------------------------------ I agree that capturing a neutral from a different circuit is a dumb idea (particularly from an EE).

I don't think it came up - the problem of no neutral at a switch is why the 2011 NEC requires a neutral (with major exceptions).

[Robert Green]

I understand the curiosity motive from EE's - how dangerous is it to pull a "foreign" neutral? But I think it does a disservice to the man in the street who wants to simply know whether he should "pull a neutral" from elsewhere. Sure, it probably won't hurt HIM, but it could kill the next person. If the OP has a bad memory, that next person could easily be him.

After years and years of seeing people pull neutrals from other circuits and the proliferation of switches and devices that need a neutral, it was long overdue.

I just wonder how much money builders saved by wiring wall switches without neutrals?

-- Bobby G.

*JOHNSTON, DONALD R. Rank and organization: Specialist Fourth Class, U.S. Army, Company D, 1st Battalion, 8th Cavalry, 1st Cavalry Division. Place and date: Tay Ninh Province, Republic of Vietnam, 21 March 1969. Entered service at: Columbus, Ga. Born: 19 November 1947, Columbus, Ga. An enemy soldier threw 3 explosive charges into their position. Sensing the danger to his comrades, Sp4c. Johnston, with complete disregard for his safety, hurled himself onto the explosive charges, smothering the detonations with his body and shielding his fellow soldiers from the blast. His heroic action saved the lives of 6 of his comrades.

[bud--]

There wasn't any need for a neutral in the past. It is the various electronic switch devices that created the need.

[JIMMIE]

remotely. =A0This would obviate my walking across the room in the dark to = get to the light switch.

ocation. =A0Several of my switches have only a hot leg coming into the box = with no neutral. =A0X10 docs. recommend simply running a neutral wire into = the box. =A0

es are on the exterior walls. =A0These locations are inaccessible from the = attic since this is where the roof meets the ceiling ergo providing mere in= ches of crawl space. =A0It would be much easier to run the neutral wire fro= m below (I have a generous 42" high crawl space). =A0

I simply come from any circuit (even a separate new circuit) and run a whi= te neutral wire to each switch box? =A0Does it have to be from the same pha= se? =A0X10 docs. do mention that if not from the same phase, then the phase= s can be joined at the box.

HUH, Unless X10 switch modules have been redesigned lately they DO NOT require a neutral. Most of my switches are on the ends of switch loops and I have replaced several switches with X10 modules. No Neutral available or required at these points..

Jimmie

[Metspitzer]

Someone that would do that should be in jail.......for a long time.

[trader4]

ts remotely. =A0This would obviate my walking across the room in the dark t= o get to the light switch.

location. =A0Several of my switches have only a hot leg coming into the bo= x with no neutral. =A0X10 docs. recommend simply running a neutral wire int= o the box. =A0

ches are on the exterior walls. =A0These locations are inaccessible from th= e attic since this is where the roof meets the ceiling ergo providing mere = inches of crawl space. =A0It would be much easier to run the neutral wire f= rom below (I have a generous 42" high crawl space). =A0

an I simply come from any circuit (even a separate new circuit) and run a w= hite neutral wire to each switch box? =A0Does it have to be from the same p= hase? =A0X10 docs. do mention that if not from the same phase, then the pha= ses can be joined at the box.

There are both kinds of X10 switch modules, ie those that don't use a neutral and those that do. The ones that don't only work with incandescent lights or similar resistive loads. The other ones are for any load. Apparently even the ones that don't use a neutral can be used with CFLs if you also provide a resistive load, eg a small incandescent night light.

I agree that if he can use one of the X10 switches that do not require a neutral it's the simplest solution to his problem.

[bob]

Did you check outside the switch box, the neutral may be there.

You may want to consider Insteon which is an improved system over X10. It is not perfect but alot better from my experience.

[clare]

OK, I can see how it would work with a GFCI BREAKER. I was thinking GFCI outlet - where it would NOT necessarily show up.

But a little hard in my house - since it is all FUSED.

[clare]

There have been areas where the inspectors DEMANDED 3 wire cable to be used to switches because the DEMANDED the power be black and the traveller red. It also made it easier to install ceiling fans.

[clare]

remotely.  This would obviate my walking across the room in the dark to get to the light switch.

location.  Several of my switches have only a hot leg coming into the box with no neutral.  X10 docs. recommend simply running a neutral wire into the box.  

are on the exterior walls.  These locations are inaccessible from the attic since this is where the roof meets the ceiling ergo providing mere inches of crawl space.  It would be much easier to run the neutral wire from below (I have a generous 42" high crawl space).  

simply come from any circuit (even a separate new circuit) and run a white neutral wire to each switch box?  Does it have to be from the same phase?  X10 docs. do mention that if not from the same phase, then the phases can be joined at the box.

If you have "incandescent only" switches there in no neutral required . Switches that can handle flourescents and electronic transformers require the neutral.

[Robert Green]

I agree. I left the organization before I found out what happened in the end, but you'd be shocked to learn which Federal agency was afflicted.

-- Bobby G.

• KEDENBURG, JOHN J. Rank and organization: Specialist Fifth Class, U.S. Army, 5th Special Forces Group (Airborne), 1st Special Forces. place and date: Republic of Vietnam, 13 June 1968. Entered service at: Brooklyn, N.Y. Born: 31 July 1946, Brooklyn, N.Y. Just as the helicopter was to lift them out of the area, the South Vietnamese team member who had been unaccounted for after the initial encounter with the enemy appeared in the landing zone. Sp5c. Kedenburg unhesitatingly gave up his place in the sling to the man and directed the helicopter pilot to leave the area. He then continued to engage the enemy who were swarming into the landing zone, killing 6 enemy soldiers before he was overpowered.

[John Gilmer]

I can see inspectors "demanding" that when normal cable is used for a switch loop that the white wire be colored but "demanding" 3 conductor (plus ground) cable is an unnecessary cost increase.

When you have 2 or so switches per room, the cost of the extra wiring definitely adds up. If someone in retrospect "needs" three conductor cable, it's just not a big thing to "fish" the cable while only making a few small holes in the drywall.

N.B.: In high rise units and other places where conduit (including some form of flexible conduit) is standard, switch loops do use a red and black covered wires. Of course in new conduit work the rules require a bit of "spare" conduit space.

[clare]

The intent - and result, of REQUIRING 3 wire cable for "tail switched" lighting circuits was to encourage "head switched" lighting circuits, so when the SWITCH is off, the entire CIRCUIT is dead. Power to the switch, then from tere to the lights - not the other way around. And that often takes more wire too.

[Robert Green]

On infrequently used lights, it's the best way to go But I'm happy that I can use socket splitters and can now replace a single bulb overhead fixture with a multiple bulb one, using a small nightlight in one of the sockets to provide a resistive load that can trickle current through to the X-10 circuitry.

This was a useful thread. This will have high SAF to be able to put some bright overhead lighting in for the fall cleaning season, which is about the only time we use them (other than for whole-house light flashing when the alarm goes off - very useful there, too).

The prices on 23W bulbs have really dropped. I guess the idea of people making do with 13W bulbs was pretty optimistic. I also noticed that the electronics pods on the last batch of 23W bulbs I bought were way smaller than those of bulbs bought two years ago. They actually fit in some of my desk lamps now.

-- Bobby G.

[bud--]

Note that clare lives in Ontario.

I agree that you should be able to re-color the white in a cable like romex.

But as I noted in a previous post, the 2011 NEC now generally requires a neutral at switch locations (404.2-C). The reason is to avoid the problem at the start of this thread. A neutral is not required if raceways have extra capacity to add a neutral, or when the wall is easily refished (including open at the top on that floor level - common in offices with drop ceilings).

If you need to add a neutral to romex it isn't usually all that easy.

(And I don't believe making holes in the drywall is what the NEC intends for the exception.)

There used to be "new-" and "old-work" tables for conduit fill; they disappeared long ago. There isn't any "spare" conduit space that can be used later.

[clare]

As the NEC now requires a neutral in that situation, these inspectors were just ahead of their time. Very often you will find Canadian requirements are more stringent, safety wise, than american - but I'm not aware these requirements were provincially, or even nationally, instituted. An inspector in many cases had the authority to require, or not require, whatever HE wanted to require or not require, if not in a "uniform code" community.

If you are using 3 way switches you need 3 wire anyway.

No, and I needed to ADD wiring to my daughter's multi-level townhouse to install ceiling lights in the bedrooms (thankfully all with "attic" exposure) and did not want the mess of punching and patching drywall - so I drilled down through the upper plates, and through the cross-bracing (fire-stop) down to the existing wall switches and fished NMD3 cable down through those 3/4" holes and into the provided holes/cable clamps in the top of the switch boxes. By re-wiring the switched receptacle I was able to use the "switch drop" cable as a power feed to the switch - allowing me to feed both a switched ceiling light and a non-switched ceiling fan. Took me 4 hours for one, two hours for the second and almost 6 for the third - but I got them done before having the attic re-insulated. It was hotter than Hades up there, even in May, and 4 foot extension bits were a NECESSITY. The fish tape with an LED lamp on the end was pretty slick too - too bad I didn't have my fancy little flex-tube inspection camera then yet- - -

-.

Unless the electrician is thinking ahead and not pinching pennies and just, as matter of habit, installs over-size for the requirement (which makes his job today, and in the future, a lot easier)

[bud--]

What an absolutely marvelous idea. The AHJ can require whatever they want.

Under the new NEC rule you need 4 wires. Often (always?) this can be wired as a California 3-way (the electrical kind) and each switch location would have a hot wire and the switched wire to the light.

You can put a lot of wires in a 1/2" conduit.