Shared neutral

[hj]

outlets

IT would be too laborious to read all the extensive posting above, but whether it was stated or not, the asker should realize that if the neutal in a combined circuit fails for any reason, all the outlets will default to 240 volts.

 

[Beekerc]

the asker should realize that if the neutal in a combined circuit fails for any reason, all the outlets will default to 240 volts.

the OP does now. if there was an easy way to find the first junction point and string another wire from the panel, i would. I suspected there might be some issues but did not have specifics. my main point was to determine if this was kosher, even though (i assume) it was inspected and approved at time of construction 40 years ago. i was looking for "it's fine", "it's okay but not recommended", "we don't it any more but it's grandfathered", or "get that out of the wall right now".

Ideally, if i can split the lines, I will, but it may range from impossible to difficult.

thanks to all for the advice and information.

 

[Sponsor]

 

[Speedy Petey]

HJ, what you say is not true. Any loads become connected in series and the resistance changes the voltage. With no load you simply have 120v to ground with no neutral.
This is all hinging on an open neutral. Wired properly and safely there is very little risk of an open neutral ahead of the multi-wire split.

This graphic is very simplistic.

 

[Beekerc]

I'm still looking to see if it's possible (and not difficult) to run a new romex from the panel to the first junction and split the circuits - for reference, both sets of runs are buried in kitchen walls behind cabinets. i did, however, stop by my neighborhood McClendon's hardware store (if you're not familiar with the greater seattle area, it's a small local family chain of stores that has been around forever and they have the greatest staff working there) and picked up a pair of breaker tie clips (or whatever they're called) so that the breakers that share a neural, which have always been adjacent to one another, are now physically tied together. the eletrical guy there (and i think i read a reference here on this board) said i could just as easily stuff a short nail in between the breaker handles, but i wanted to go with a proper solution so i got the corresponding manufacturer's clips.

eh, not ideal yet, but at least i have double pole breakers now.

 

[JWelectric]

the OP does now. if there was an easy way to find the first junction point and string another wire from the panel, i would. I suspected there might be some issues but did not have specifics. my main point was to determine if this was kosher, even though (i assume) it was inspected and approved at time of construction 40 years ago.

It is important to understand that just because something was inspected in no way means that it is correct. Code officials are no different than any other people and make mistakes either due to not knowing the difference or just not seeing a violation

i was looking for "it's fine",

It is perfectly fine and there is absolutely no danger in the installation at all as long as it was installed correctly and remains correct.
I make multiwire installations all the time as it is both cost effective and saves on labor

"it's okay but not recommended",

Yes it is okay and it is also the only way to wire such items as dryers and ranges in dwelling units.

"we don't it any more but it's grandfathered",

Not Grandfathered but a code compliant installation today

or "get that out of the wall right now".

Only if the circuit is damaged and need replacing for reasons other than it is a multiwire circuit

Ideally, if i can split the lines, I will, but it may range from impossible to difficult.

thanks to all for the advice and information.

I think that impracticable would be a better adjective.
There is absolutely nothing wrong with the installation and let no one instill fears concerning the installation. As in the experiment that I post with the two lights, if you lose the neutral coming from the service into the house the entire house becomes a 240 volt series circuit. This is the most common aliment with service drops.

eh, not ideal yet, but at least i have double pole breakers now.

Never use a nail as this is nothing but hack type work. Even as a do-it-yourselfer you want to make a professional installation.
What you have is still two single pole breakers but they are tied together. It is possible that one would trip without opening both. A double pole breaker would open both if only one trips.

 

[Beekerc]

thanks for a very informative and thorough post jw.

Never use a nail as this is nothing but hack type work. Even as a do-it-yourselfer you want to make a professional installation.
What you have is still two single pole breakers but they are tied together. It is possible that one would trip without opening both. A double pole breaker would open both if only one trips.

i would not use a nail, it simply sounds hackish and amateur, looks bad and would be too easy to defeat, even accidentally, which is why i went with the OEM made bridge clip - granted it's a piece of stamped sheet metal folded the way it needs to be, but it is made by the same mfr as the breaker. as best i can tell a double pole breaker is simply two single breakers with the handles permanently bonded together, so the only difference is the strength of the bonding mechanism attached to the toggles. i can visualize the possibility of one breaker tripping but not taking the other one with it, but if this were a likely scenario, would the manufacturer have designed a bridge clip that would be stiff enough to esure the other breaker would forced to trip?

not to suggest that a company would make or market a dangerous product, but i suppose that from the profits that they make on these clips (probably less than $0.01 worth of metal and manfacturing, sold for more than a buck) the would be able to afford to pay off the (statistically derived) number of lawsuits that arose from malfunction, than to not make them and only sell double pole breakers or design and manufacture a better and safer clip.

so in the opinions of the pro's - are the bridge clips safe and reliable or not recommended.

i know, the argument - $15 for a double pole breaker vs $1.50 for the clip - is the safety of my house and my family worth the extra $13.50? the answer is obvious, but at some point all those little numbers add up to a big number and unless one is in the top tax bracket, one has to apply probabilities and likelihoods (and actuarial methods if so inclined) to determine what is really the smart and cost effective way to go.

 

[JWelectric]

with the handles permanently bonded together, so the only difference is the strength of the bonding mechanism attached to the toggles. i can visualize the possibility of one breaker tripping but not taking the other one with it, but if this were a likely scenario, would the manufacturer have designed a bridge clip that would be stiff enough to esure the other breaker would forced to trip?.

A handle tie ties two single pole breakers together. Each of these breakers still has the ability to open independently of each other.
A two pole breaker has an internal mechanism that opens both poles in the event that one opens. Try pulling the handle tie off a two pole breaker and see if they are one breaker or two. The handle tie will go back on with a little work.
The handle tie means that when you turn one off you turn both off just as in a two pole breaker.