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-   -   old house wiring...not code (http://www.diychatroom.com/f18/old-house-wiring-not-code-54471/)

fisherman2001 10-05-2009 11:58 AM

old house wiring...not code
 
I bought an old house....In the attic there is a 10gauge run of (old)Romex which contains 2 insulated wires and a bare ground. It comes from the main panel and is attached to a 2 pole 30 amp breaker. Ground wire on ground/neutral bus. So far so good This wire in the attic enters a subpanel wherein the 2 hots are on the breaker bars and the ground wire is on the neutral bar. There is no 4th wire or equipment ground bar. This subpanel then has one 15 amp single pole breaker which then feeds some ceiling lights.

So while this is a code violation, what is the specific risk here? By code a ground and neutral wire go to the same bar in the main panel anyway, and the lights work fine.....let me have it, I am sure this is obvious but dont know.

Thanks

Magnettica 10-05-2009 12:57 PM

The bare wire is being used as a neutral and it needs to be insulated, it is not.

Also, because the bare wire is being used a neutral, you therefore have no equipment ground.

Why is this bad? Because in the event you have a "ground fault" there is no conductor to carry the ground fault current back to the source.

Worst case scenario is the panel provides only 120 volts. Be sure the equipment grounding buss is isolated from the neutral to prevent objectionable current flow.

hayewe farm 10-05-2009 04:10 PM

The easiest thing to do is replace the double pole breaker in the main panel with a single pole breaker, connect the white wire the the buss. Then in the sub panel connect the white wire to the buss.

bob22 10-05-2009 06:42 PM

Isn't the bare wire now a neutral on a 120 v circuit if Hayewe's idea is used?
Still an issue I would think?

220/221 10-05-2009 09:16 PM

Quote:

So while this is a code violation, what is the specific risk here?
Picture this. Better yet, draw it.

In a specific fault condition, which is not highly unlikely in a lot of cases, your neutral to "sub" panel gets broken/disconnected/burned...faulted connection somehow.

Neutral and ground wire in sub are on the same bus.

You have something grounded.....let's say a refrigerator..... plugged in to one or more of the circuits supplied by the panel.

The current from the breaker will be going thru the refer and back on the neutral but it can't make it's way back to the neutral/ground at the main source so it will travel thru the ground back to the refer recep, thru the grond pin on the plug and energize the metal frame of the refer. When you grab the refer barefoot, you will complete the circuit.

If there is a garage door plugged into a branch circuit from that panel, the whole garage door and hardware will be a possible path for the current and a barefoot kid playing in the driveway becomes a conductor.

The possibilities are many.

The same thing can and does happen at the service but by making the service the only place it's allowed minimizes the risk.

jbfan 10-05-2009 09:48 PM

Quote:

Originally Posted by bob22 (Post 336777)
Isn't the bare wire now a neutral on a 120 v circuit if Hayewe's idea is used?
Still an issue I would think?

He would need to add a ground bar and seperate the ground and neutral.

Scuba_Dave 10-05-2009 09:52 PM

Yes...the specific risk is death
Many unsafe wires in an older house
I had more then my share at my old house - built in 1905
Rewired by a hack around 1979

spark plug 10-05-2009 10:03 PM

Quote:

Originally Posted by bob22 (Post 336777)
Isn't the bare wire now a neutral on a 120 v circuit if Hayewe's idea is used?
Still an issue I would think?

No. Because, this now a 120V. circuit, the White wire (originally part of a MWBC) IS the NEUTRAL! And the bare wire is GROUND. ....And everything is fine and dandy.. And they lived happily ever after. (You've got to inject some light Humor in the most serious of situations.! (No matter what) :laughing::no::drink:Don't Drink and Drive. Ever!!!

MI-Roger 10-06-2009 08:17 AM

What about amperage of new SP breaker?
 
I am assuming it should be 15 or 20A maximum as it is used for a lighting circuit. The existing 10GA wire can handle 30A (depending on total length of the run), but will placing ceiling fuxtures on a 30A circuit cause another code non-compliance?

AllanJ 10-06-2009 08:18 AM

Double check the ground/neutral bus bar in the subpanel. If it has metal-metal contact with the panel frame, you need to install a neutral bus with a plastic liner and no such metal to metal contact. If not then you need to install a ground bus (with such metal to metal contact). Move the white and bare wires to match (after making sure that the other end of the white feed line down at the main panel has been moved to the neutral bus there first).

The breaker(s) in the subpanel for ordinary branch circuits would be/stay 15 and/or 20 amps. Lights and regular receptacles may be on a circuit (or subcircuit if you insist) of at most 20 amps.

The subpanel is there to prevent putting lights and receptacles directly on a 30 amp circuit which the 10 gauge wires going to the main panel can stay as.

HouseHelper 10-06-2009 08:22 AM

Quote:

Originally Posted by MI-Roger (Post 336967)
I am assuming it should be 15 or 20A maximum as it is used for a lighting circuit. The existing 10GA wire can handle 30A (depending on total length of the run), but will placing ceiling fuxtures on a 30A circuit cause another code non-compliance?

Maximum breaker size for 120V lighting and receptacles in a dwelling is 20A.

jbfan 10-06-2009 08:24 AM

Quote:

Originally Posted by MI-Roger (Post 336967)
I am assuming it should be 15 or 20A maximum as it is used for a lighting circuit. The existing 10GA wire can handle 30A (depending on total length of the run), but will placing ceiling fuxtures on a 30A circuit cause another code non-compliance?

He is feeding the panel with the 30 amp, and has 1 15 amp lighting circuit from the panel.

MI-Roger 10-06-2009 08:39 AM

OK, I didn't state one of my assumptions.....
 
Why even keep the sub-panel? It only feeds one circuit ,which can be just as easily fed from the mainpanel using the existing 10GA NMC and a new single pole breaker of appropriate size.

Doesn't the code require all panels and all breakers to be easily accessible? I would not consider a sub-panel located in an attic to qualify as easily accessible. Removing the subpanel would eliminate a lot of potential problems.

My assumption was that this panel would be eliminated.

220/221 10-06-2009 07:30 PM

Quote:

Why even keep the sub-panel? It only feeds one circuit ,which can be just as easily fed from the mainpanel using the existing 10GA NMC and a new single pole breaker of appropriate size.

Why didn't I think of that? :jester:


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