newbie - help with outlets and light outage

[doanh]

I could use some help with this strange problem we got yesterday..

I was changing out some of the valves of the sprinkler system and testing it. About 1 hr later, my wife tells me the laundry room light switch no longer work and the electrical outlets are not working in the library. The library and the laundry room share one wall.

It is strange to me since the outlets in the laundry room are working fine but the light switch is dead. The library light switch is working fine but the outlets are dead..

As I mentioned earlier, the library and laundry room share one wall.

I checked all the breakers and reset it but the problem remains. I used a multimeter on the breakers and the voltage readings are good.

the house was built in 2005 so it is not that old. I am trying to see if the builder has the electrical diagram but I highly doubt that.

as i continue to investigate, I found out that the light switch is on the same circuit as my outdoor and entry way. The outlets in the laundry room are on its own circuit per label of the electrical panel.

I really could use some suggestions on where to start this investigation.

[HayZee518]

any outlets outside, in the garage or at grade level are supposed to be ground fault protected. check to see if any gfci outlets have tripped. outlets in your laundry connected to a washer need not be gfci protected unless they are within 6 feet of a sink.

[doanh]

the garage outlet is on a different circuit but it is a GFCI outlet. I checked that already. All the outside plugs are tied to this outlet.

The Washer is on a separate outlet and about 20 ft from the sink, thus not GFCI protected.

[HayZee518]

ok then we will have to do some back tracking. the outlets that share the same wall it is safe to assume that those outlets are wired "back to back" by this I mean a line feeds into an outlet and a cable is fed from here to the outlet on the other side of the wall. from here it may loop to another outlet on that wall. if you know which outlet is the last on that string you won't need to remove it. go to the one previous to this one and remove it from the box. in 2005 eagle company made back stab outlets with no terminal screws. you'd just strip a wire and stick it into the backside of the outlet. the wire made contact with a spring loaded bronze contact. sometimes a wire would "nick" during stripping the insulation and when pushed back into the box, the wire would break causing an open and loss of that string. other outlets had no screws just wires coming out the back and you'd connect them with wirenuts. oft times the solid wire would break in the wirenut. it looks ok but it is an open. check for this. some contractors would just strip the insulation and group wires together and apply a wirenut without physically twisting the group to mechanically tie them together. something else to check. the 1998 code made it mandatory to utilize arc fault circuit breakers in every habitable bedroom, because people had a habit of putting nails in a wall to hang pictures and inadvertenly punctured wires that were staples to the sides of 2x4s. the code now a days makes it a must to use these arc fault breakers on any new construction - at 39 bucks a pop it makes for an awfully expensive wiring nightmare for houses. about the only places you can use standard breakers is for dedicated circuits like for a laundry or garage, and there you are required to have at least one gfci protected outlet.

[doanh]

the four outlets that are dead in the library are not on the same circuit with the shared wall of the laundry room. I tested the two outlets with the shared wall by pulling them out and use a Non-Contact Voltage Tester to sense the wires. there is no power in any of the leads.

since it is a single story house, I can get into the attic and check the power to the lights.

I checked all GFCI outlets and they are all ok.

I noticed that the panel has three breakers labeled lights and plugs. one breaker controls the lights in living room and dinning room. One breaker controls the lights in the entry way, library and outside fronts. the other ones control the lights in kitchen.

all the bedrooms are on a separate circuits and breakers (two bedrooms per circuit/breaker).

there is a breaker for sprinkler which I have no idea where that circuit is located...

[HayZee518]

I personally don't trust any non contact voltage detector. I have used these detectors on a known neutral that was tested DEAD and it returned a live indication. An analog voltage tester is a must for troubleshooting. Neutrals for some odd reason - open. Try to trace where the wire goes after leaving the panelbox. It might go to a junction box, it might go up through a hole in a bottom plate to an outlet or wall switchbox. You'll need to try to visualize where its going when it penetrates a hole in the floor[ceiling] in the basement. If your house is built on a slab, then the wire could go anyplace, most obviously horizontally through studs to either an outlet box or wall switchbox. if it goes to an outlet, then a feed goes up to a switchbox, feeds a switch and the load comes off the top of the box to a ceiling fixture or a wall sconce. outlets and lighting are all in parallel. you'll never find a series connection. only thing in series with a load is a switch leg.