Any safety issue (backfeed)?

[busman]

I was on a call last Saturday (HO tried to replace photocell and sparks flew). Turns out that the reason there were sparks was the he tried to do it HOT because he couldn't find a breaker to shut the light off. The reason was a backfeed. I identified the two conductors in the panel that are crossed downstream and tried for about an hour to find the backfeed without success. It was getting late, so I tied both conductors together and attached to ONE 15A breaker as a temporary until I can get back and find the backfeed.

The question is: This violates two code rules (parallel conductors and all conductors of the same circuit in the same cable), can you see any real hazard in the short run? Since each of the parallel conductors is capable of carrying the entire 15A load, I don't see any hazard there. I would think that the parallel currents would split the same way in the hots and neutrals and not cause inductive heating. I would think the biggest problem would be overloading the circuit (two circuits are sharing 15A). I told the HO this might happen and to call me if the CB trips. I'm going back tomorrow.

Any thoughts? You guys ever do this.

Thanks,

Mark

 

[brian john]

Had a job last summer where a 277 VAC circuit was back fed into a 208/120 VAC panel when the CB was turned on the GFP on a 4000 Amp main tripped.


Having voltage present where one would not expect it.
Safety 277 in 208/120 VAC panel.
Safety, dark building trying to exit.
Shutting down tenants.
Did I mention having voltage present where one would not expect it.

Use a tester, use a tester, use a tester, use a tester.

 

[busman]

That's why I thought my solution was a pretty good one. The whole 2 crossed circuits are on ONE breaker so either it's on or it's off. No voltage where you don't expect it.

On a related note Brian, I did get shocked in my own home about a month ago due to that problem. I was installing a standby generator and pulled some cables from the main panel to put them in the sub-panel. It turns out that one WAS backfed and was still hot after being removed. I learned that lesson the hard way.

Mark

 

[wireguru]

Had a job last summer where a 277 VAC circuit was back fed into a 208/120 VAC panel when the CB was turned on the GFP on a 4000 Amp main tripped.


Having voltage present where one would not expect it.
Safety 277 in 208/120 VAC panel.
Safety, dark building trying to exit.
Shutting down tenants.
Did I mention having voltage present where one would not expect it.

Use a tester, use a tester, use a tester, use a tester.

wow. that probably would have caused quite a mess if there was no gfp on the main....

 

[K8MHZ]

A hand from IBEW LU 697 was killed in January due to a back fed circuit.

To make matters worse it was due to a 56 volt ground fault on the grounding conductor he was trying to replace. The original conductor had been cut and stolen for the copper.

He was 31 and had a wife and child.

 

[220/221]

I did a service call a couple weeks ago. I opened the panel and found a capped wire and a note fron 1999 indicating that the capped wire was backfed.

It was my handwriting.

Obviously I had been there (apartment) 9 years earlier and decided not to take the time to find the issue.

This apartment had a few different issues including some really loose recepticals so I took the time to ring out everything and found the extra jumper from the original 1978 installation.

 

[cadpoint]

I did a service call a couple weeks ago.
....
This apartment had a few different issues including some really loose recepticals so I took the time to ring out everything and found the extra jumper from the original 1978 installation.

Priceless ...

 

[chris kennedy]

Since each of the parallel conductors is capable of carrying the entire 15A load, I don't see any hazard there.

But you have a potential 30A load on a 15A breaker.

 

[don_resqcapt19]

But you have a potential 30A load on a 15A breaker.

And that is a hazard? When the breaker sees too much current it will trip. The wire is still protected.

 

[Energize]

And that is a hazard? When the breaker sees too much current it will trip. The wire is still protected.

Hey, I like that thinking! Thinking like that will save me a lot of breakers! I will just tie all the 12's to one 20 amp breaker and all the 14's to one 15 amp breaker and show the the customer how to reset the breaker!

 

[don_resqcapt19]

Hey, I like that thinking! Thinking like that will save me a lot of breakers! I will just tie all the 12's to one 20 amp breaker and all the 14's to one 15 amp breaker and show the the customer how to reset the breaker!

As long as you supply the number of circuits that are required by the code, you can do that.

 

[monkey]

busman, why didn't you just remove one of them and cap it up? Both circuits would still be energized, but only one feed.

If one is a 20 and one is a 15, check the bathroom 2 gangs. I've seen where they tie the lighting together with the gfci because they're in the same box.

 

[mdshunk]

If one is a 20 and one is a 15, check the bathroom 2 gangs. I've seen where they tie the lighting together with the gfci because they're in the same box.

That's the same thing I was going to suggest. Kitchen and bathroom 2-gangs.

When retrofitting AFCI's in old work, I find a lot of intermixed neutrals in multi-gang boxes. The addition of an AFCI declares these in a hurry. They can be a little tough to find, but they're almost always in a 2-gang box, or in a junction box in the basement.

 

[Energize]

As long as you supply the number of circuits that are required by the code, you can do that.

No wonder the code book gets thicker every cycle....

It has to specifically list every single thing you cannot do because some literal person will say "show me where it says I can't do that." That's the kind of thinking that has us to the point of placing warning labels on using hair dryers in bathtubs and forks in toasters. "Well, it didn't specifically say I couldn't use it in the tub" or "it didn't specifically say I couldn't stick the fork in the toaster."

Hopefully evolution will be allowed to take its course and thin the herd so common sense can sping up from the burden of paperwork needed to make the world idiot-proof.

 

[busman]

busman, why didn't you just remove one of them and cap it up? Both circuits would still be energized, but only one feed.

Because I didn't think of that. So if I did that, would I then be required by code to find the backfeed and correct it, or does it become a compliant installation (as long as the load is not exceeded?)

If one is a 20 and one is a 15, check the bathroom 2 gangs. I've seen where they tie the lighting together with the gfci because they're in the same box.

I usually check kitchens and bathrooms first for just that reason. The one in my home was the disposal and the lights (both switches in a 2-gang box).

 

[ptonsparky]

Hey, I like that thinking! Thinking like that will save me a lot of breakers! I will just tie all the 12's to one 20 amp breaker and all the 14's to one 15 amp breaker and show the the customer how to reset the breaker!

I have 3 SABC in our small kitchen. Two duplex each circuit. 1200 - 1500 watt applianes are not uncommon. I have a possible load of 25A per duplex. 50A per circuit. I think this was attempted by my wife in the first couple Sunday morning breakfasts in her new kitchen.

Do you split wire each duplex just to limit the possible load?