Sub panel issue

[djd99]

I just installed a Siemens 100 amp 20 space panel QP, The issue I'm having is when certain breakers are on there's 25 volts bleeding thru the breaker to the other leg when it's off. The thing in common is all 12/3 lines and 14/3 lins are doing this. Box is unbonded being it's a sub panel. What am I missing? I'm feeding this box off a 50 amp breaker running 50' of 2 reds/white/green #6 thhn.

 

[pattenp]

Are you using a digital meter? If so I believe you are getting ghost voltage readings.

 

[djd99]

Are you using a digital meter? If so I believe you are getting ghost voltage readings.

Yes I am. What should I use to confirm this?

 

[pattenp]

Use either a test light type indicator or an analog style volt meter.

 

[Adrien]

Here's a bit of an explanation: http://www.hattonmarine.com/docs/ghostvoltage.pdf

Adrien

 

[pattenp]

Here's more on ghost reading with a DMM.
http://www.supplylink.com/article/new-multimeter-detects-ghost-voltages

 

[Gary S]

Use either a test light type indicator or an analog style volt meter.

Simpler is always better. A test light is the simplest measuring device, so it is the least likely to give false readings. However, it can't tell you voltage level. The old cheap analog meters are next on the "simple" list. They often will read correctly where the expensive digital meters can't.
I spent over 40 years in the electronics industry. Often when working around RF equipment, the expensive digital meters gave me false readings and the $10 old analog meter would get it right.

 

[timewarp]

14-3 and 12-3 mean Multiwire branch circuits, the 2 breakers need to be tied together so they are both off or on at the same time.

 

[djd99]

14-3 and 12-3 mean Multiwire branch circuits, the 2 breakers need to be tied together so they are both off or on at the same time.

I thought this was only the case when you used this wire on one circuit you needed double pole breakers. All of my runs of 12/3 and 14/3 run 2 circuits on single breakers. If each wire runs 2 circuits why the need for double pole breakers your only using the wire to save from running more 14/2 or 12/2?

So I guess I don't get the need for double pole breakers/. Ie I have my lights run on 1 14/3 with 8 zones, 4 zones per circuit.
I wanted to turn each off individually if I needed you can't do that with doulble pole breakers.

Also I bought The a generic 2 wire tester and the digital readings were false, I don't have power to those circuits when there off.

 

[54FordPanel]

It's a safety issue.
When somebody turns off the breaker to work on the circuit, both hots must be turned off at the same time.

 

[djd99]

It's a safety issue.
When somebody turns off the breaker to work on the circuit, both hots must be turned off at the same time.

Is this required for code to have 2 pole breakers on all 14/3 and 12/3 lines even if there running 2 circuits each?

I currently have them on single breakers.

 

[Norcal]

Is this required for code to have 2 pole breakers on all 14/3 and 12/3 lines even if there running 2 circuits each?

I currently have them on single breakers.

Yes, NEC art 210.4(B)

(B) Disconnecting Means. Each multiwire branch circuit
shall be provided with a means that will simultaneously
disconnect all ungrounded conductors at the point where
the branch circuit originates.

 

[Alchymist]

Is this required for code to have 2 pole breakers on all 14/3 and 12/3 lines even if there running 2 circuits each?

I currently have them on single breakers.

Whichever "electrician" wired them to individual breakers was ***** the fence than his partner which is why the partner fell off.

 

[djd99]

Whichever "electrician" wired them to individual breakers was ***** the fence than his partner which is why the partner fell off.

Well that ***** is me so thanks for the insult, anyway I just got back from the supply house with a box of double breakers so apparently I won't hurt myself. I wired them with singles thinking I can turn them off independently being the on separate circuits, but if it's not code I'll do it right.

Side note the supply house said it's done all the time and overlooked but I would rather be safe then sorry.

 

[Mmfh]

Hey Don,
Would you happen to have a picture or two of what you are doing, what you did in the first place sounds like the way I always have done it.

If that's not right, I would very much like to see the right way so I can do it right in my upcoming sub-panel install.

Sounds to me that you have two light circuits, both have their own breakers. Both have 4 lights on that run. You can turn off one breaker and kill 4 lights without affecting the other 4.

If that is what you did, what's wrong with that?? I would have thought that was the way to do it. Now you are running both light circuits into a double pole breaker? Why is that safer?

I'm not trying to act stupid, I just don't understand the reasoning here. If you are going to work on one of the circuits, you kill the breaker for that circuit, right?

Thanks

 

[djd99]

Hey Don,
Would you happen to have a picture or two of what you are doing, what you did in the first place sounds like the way I always have done it.

If that's not right, I would very much like to see the right way so I can do it right in my upcoming sub-panel install.

Thanks

Sure I can take a pic of my install, what I did was instead of running 2 separate 14/2 wires I ran 1 14/4 over to my switch bank witch I have 4 switches per bank 4 switches per circuit for 2 circuits.

I ran the 14/3 to 2 separate 15 amp breakers witch apparently where this safety issue comes to play. Witch I do understand as I have 2 hots in one box and by having them on separate breakers if you only turn one off the other is still live. I guess better be safe then not so I bought double pole breakers and will install today and will take a pic before I install them and after for that matter.

Still not looking forward to installing 25 outlets in the ceiling how fun. You can never have too much light.

 

[Mmfh]

You can never have too much light is right! 25 over your head to do, man I feel sorry for your shoulders and neck

I understand more now that you broke that down than I did before. I know I've done things where there were two different hots from two different circuits in one box before.

Like running conduit down a wall and having a box at a drop point. You could have a hot for the drop as well as the circuit the conduit continues on too in that box where it drops.

A little different than what you are doing, I guess I just didn't think of it that way before.

Thanks

 

[Alchymist]

Well that ***** is me so thanks for the insult, anyway I just got back from the supply house with a box of double breakers so apparently I won't hurt myself. I wired them with singles thinking I can turn them off independently being the on separate circuits, but if it's not code I'll do it right.

Side note the supply house said it's done all the time and overlooked but I would rather be safe then sorry.

OK, my apologies. Obviously you're NOT a ***** - you chose to make things right when called to your attention. Just one of those details that catch the DIY'er unawares sometimes.

 

[BigJohn20]

Sure I can take a pic of my install, what I did was instead of running 2 separate 14/2 wires I ran 1 14/4 over to my switch bank witch I have 4 switches per bank 4 switches per circuit for 2 circuits.

I ran the 14/3 to 2 separate 15 amp breakers witch apparently where this safety issue comes to play. Witch I do understand as I have 2 hots in one box and by having them on separate breakers if you only turn one off the other is still live. I guess better be safe then not so I bought double pole breakers and will install today and will take a pic before I install them and after for that matter.

Still not looking forward to installing 25 outlets in the ceiling how fun. You can never have too much light.

What you have is what's called a MWBC (multi-wire branch circuit). To paraphrase a bit, it's when two breakers share a neutral but they're on separate legs.

The reason you have a simultaneous disconnecting means (either double-pole breakers OR handle-tied breakers) is two-fold:
1) Kill one breaker and not the other and you still have a neutral with current passing through it. People get shocked from neutrals all the time.
2) If you lose a neutral on a MWBC and have electronics on it, you're going to likely have to replace those electronics. I'm not going to get into explaining why, but it is a costly mistake to lose a neutral on a MWBC.

 

[theoldwizard1]

"Ghost voltage". Interesting !

Solution: "use a DMM with a low input impedance". Obviously, a test lamp has low impedance (i.e. it actually draws milliamps worth of current) which cause the ghost voltage to disappear.

Funny, because back prior to DVMs, analog meters were typically low enough impedance that they could affect electronic circuits. That is why there used to be a device called a "Vacuum Tube Volt Meter" (VTVM) which was specifically designed to have a HIGH input impedance.

How times have changed.

So do most "sparkies" have a low impedance meter ?

 

[Roots]

Funny, because back prior to DVMs, analog meters were typically low enough impedance that they could affect electronic circuits. That is why there used to be a device called a "Vacuum Tube Volt Meter" (VTVM) which was specifically designed to have a HIGH input impedance.

How times have changed.

So do most "sparkies" have a low impedance meter ?

Pretty much every trouble shooting "sparky" has both.

 

[Alchymist]

So do most "sparkies" have a low impedance meter ?

Analog, (Simpson 360), digital, clamp-on Amprobe, tic tracer, neon light, 25 watt bulb w/leads, and more...all depends on what you're measuring.