Multi-wire Circuits the Movie

Multi-wire circuits can be confusing to people. 

How multi-wire circuits function, and problems related to them, are important to understand for electrical safety.  In a multi-wire circuit, the neutral (grounded conductor) is shared between two circuits.  Most circuits have their own neutral.  Generally speaking, multi-wire circuits perform just fine as long as the rules of installation are not violated.

Each leg of the multi-wire circuit must terminate on a different bus bar. 

Because bus bars are 180 degrees out of sync with each other, the neutral current can travel on the neutral wire safely.  If they were to terminate on the same bus bar, the current from the two circuits gets added together.  This is because the circuits are no longer 180 degrees out of sync with each other.  Wiring the circuits this way can result in overloading the neutral.  The amount of current leaving the breaker however, would not be more than normal and the circuit breaker would not trip even with the overheating wire.

The following read-along, video-blog attempts to discuss some of these issues.  Please pause or rewind the video where necessary to suit your own level of understanding and learning curve.  The demonstration board is set up to do many more experiments than what this post is about, so pay more attention to the overlays in the presentation and ignore all the rest.  Perhaps some of the other components will show up in a future post.

Charles Buell, Real Estate Inspections in Seattle

 

How could anyone do this with a straight face?

To state that the kitchen had some electrical issues would be accurate. That there was only one circuit for all the receptacles in the kitchen is not that unusual—if the house was from 1900—but this was basically “new” work, done less than 7 years ago.

The work was “less than professional” and most likely the work had no chance of being done under permit.

If this was the end of the story you would be perfectly justified in just clicking away–but hang in there, you just know it has to get better.

So this one circuit “begins” on one side of the kitchen where it picks up the refrigerator. It then wiggles its way over to the adjacent bathroom receptacle. It then goes through the wall to kitchen receptacle number one, toward the kitchen sink and receptacle number two where it then goes past the kitchen sink to receptacle number three—and then “apparently” to number four on the side panel of the washer/dryer.

But wait a minute–how come I haven’t said GFCI yet? So I plugged my little 3-bulb tester into a receptacle and pushed the test button. I heard the familiar “snap” as the GFCI tripped.

Now imagine in your own mind, a whole bunch of words I am saying in my mind, that I cannot use in this post.

The “snap” came from behind the stacking washer/dryer at the end of the kitchen countertop—behind the side panel that encloses the washer/dryer.

How could anyone do this?

But wait a minute–as it turns out, the WASHING MACHINE is the first receptacle in the circuit, not the last as I originally thought, and of course they are all GFCI protected–bathroom included!

For those of you that do not know–there is required to be at least two countertop appliance circuits. The washing machine needs its own circuit. The bathroom needs its own circuit (or at least a circuit separate from the things that it shares in this case).

The chorus:

How could anyone do this?

It least it gave me the reason why the sloppily installed receptacle on the side panel of the washer/dryer was not functional. AHHHH those silver linings!

It was not actually a receptacle at all, as you can see in the picture I was able to get with my camera over the top of the stacked washer/dryer.

It was one of those fake receptacles that people put over a hole in the wall where they hide their flash-drives, drugs and mad money.

Now you can see it through the access hole.

Well it seems at least the “Why would anyone do this,” is at least a little bit better.

By Charles Buell, Real Estate Inspections in Seattle

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Honey—what is that buzzing sound in the garage? It has been doing it all day!

Current requirements call for their being GFCI protection of ALL 120 volt receptacles in your home’s garage.  There used to be exceptions for dedicated refrigerator circuits and garage door openers but now these exceptions are no longer allowed in most jurisdictions.

gfci

GFCI

Some people argue that putting refrigerators and freezers on GFCI protected receptacles could result in the refrigerator or freezer not having any power and this might go un-noticed resulting in the thawing of foods.

I think in time refrigerators and freezers will all have lights and alarms to let you know when power has been lost—-some do already.  There are also some handy little devices like the  THP 207, POWER FAILURE ALARM & SAFETY LIGHT, that can be purchased to do the same thing.

These devices plug into the receptacle that the refrigerator or freezer is plugged into.  They are also great to use in conjunction with sump pumps.  When power is lost, an alarm sounds and emergency lighting comes on.  They are designed to hold a charge for up to 8 hours—-enough time for the homeowner to wonder what the heck that noise out in the garage is—-and go turn the tripped GFCI back on.

Inspectors will love these things too when they inadvertently trip a GFCI and they can’t find the location of the GFCI—as long as it is plugged into the same receptacle that has the GFCI device 🙂 .

 

 

By Charles Buell, Real Estate Inspections in Seattle

If you enjoyed this post, and would like to get notices of new posts to my blog, please subscribe via email in the little box to the right. I promise NO spamming of your email :-D