Condominium Wiring Hazard?

[stuckinlodi]

A four story condominium project covering a four city block area has underground parking and many electrical distribution rooms for gangs of meter/mains to each unit. Each unit has indiviual electrical circuit breaker panels of the unit loads and then one circuit from each unit is extended to HVAC condensors on the roof. At the roof I notice that several of the circuits are combined in NEma 3R gutters and two gang bell boxes and not labeled to indicate which unit they originate from or how to disconnect the power. From these boxes and gutters they continue to the condensors some as much at 15 feet away and terminate at non fused disconnects which are labeled with the unit number. I see many problems with combining circuits from differently metered and controlled panels not to mention the lack of labeling. I also see this as a problem and violation of NEC 110-10, where who knows what would happen if two non grounded conductors were to cross due to insulation problems in the combined gutter or junction boxes. Would there be adequate protection for such long conductor lengths from the first floor to the roof and back to a possible other unit on a different floor to trip a breaker or have a melt down? The electrical engineer of record sees no code violation?

 

[texie]

Seen this many times in multifamily projects. I don't think it violates NEC, BUT I know many utilities forbid seperately metered conductors in the same raceway, enclosures (except in meter centers), etc. and also some local codes forbid the practice. IMHO this is a very poor practice.

 

[augie47]

I don't see a 110.10 problem. I do see 200.6 problems

 

[texie]

Additional comment to my previous post:
Typical scenario: unit owner/tenant calls a/c guy for no cool. A/C guy says power is at the panel in the unit but not at the roof disconnect and the contactor is pulling in, call an electrician. We come and find the condensor is wired to the wrong unit and that unit moved out and had the power turned off. This usually leads to more questions such as witch unit is powering the condensor in the unit with no power and who owes who money for power used.... and on and on. In a project as big as the OP's I'd be willing to bet you will find some mixed up. Been there more than once.

 

[iwire]

At the roof I notice that several of the circuits are combined in NEma 3R gutters and two gang bell boxes and not labeled to indicate which unit they originate from or how to disconnect the power.

These is no NEC section that I am aware of that would that labeling.

From these boxes and gutters they continue to the condensers some as much at 15 feet away and terminate at non fused disconnects which are labeled with the unit number.

The labeling of disconnects is required.

I see many problems with combining circuits from differently metered and controlled panels

That is not an NEC violation that I am aware of.

who knows what would happen if two non grounded conductors were to cross due to insulation problems in the combined gutter or junction boxes.

It would be a short circuit, no worse or no more dangerous than a short between two ungrounded conductors from the same metered panel.

Would there be adequate protection for such long conductor lengths from the first floor to the roof and back to a possible other unit on a different floor to trip a breaker or have a melt down?

Electrically it is no different than a circuit that long from one meter.

The electrical engineer of record sees no code violation?

Other than 200.6 I don't either.

 

[stuckinlodi]

200.6(D) would not apply since there are no grouded conductors on the 2 wire 240 volt circuit. White conductors were not phased taped black or red as they should have been and are not really grounded conductors.


Article 110-10 "...assumes that a fault will be between two circuit conductors of the same source or between the circuit conductor and the equipment grounding conductor..."

Since as you will see none of the spliced grounding conductors are even bonded to the enclosure or together I am not sure what the difference in potential is for each one of these ground wires. Yes they are combined systems back at the 4000 amp service, but separated thereon from the main electrical room. I am also assuming the the sealtight is just a shield and may be an extension of MC Cable that has been stripped back under the roof and coupled with the sealtight. Like I said I saw many problems with the installation and did not post a complete list. I am focused on the impedance and what would happen in a fault condition.

So does this meet the last requirement of the section, " Listed equipment applied in accordance with their listing shall be considered to meet the requirements of this section"?

 

[resistance]

If i?m not mistaken, I see a violation of 350.30 or 356.30, and as mentioned 200.6.

 

[resistance]

Maybe an exception was given for 350 or 356—due to it’s location.

 

[augie47]

200.6(D) would not apply since there are no grouded conductors on the 2 wire 240 volt circuit. White conductors were not phased taped black or red as they should have been and are not really grounded conductors.


Article 110-10 "...assumes that a fault will be between two circuit conductors of the same source or between the circuit conductor and the equipment grounding conductor..."

Since as you will see none of the spliced grounding conductors are even bonded to the enclosure or together I am not sure what the difference in potential is for each one of these ground wires. Yes they are combined systems back at the 4000 amp service, but separated thereon from the main electrical room. I am also assuming the the sealtight is just a shield and may be an extension of MC Cable that has been stripped back under the roof and coupled with the sealtight. Like I said I saw many problems with the installation and did not post a complete list. I am focused on the impedance and what would happen in a fault condition.

So does this meet the last requirement of the section, " Listed equipment applied in accordance with their listing shall be considered to meet the requirements of this section"?

If there are no grounded conductors, then 200.7(C) would apply rather han 200.6. and I agree 250. 134 would require some acceptable means of groundinbg the wireway itself.

 

[iwire]

200.6(D) would not apply since there are no grouded conductors on the 2 wire 240 volt circuit. White conductors were not phased taped black or red as they should have been and are not really grounded conductors.

That is a violtion of 200.7 than.

Article 110-10 "...assumes that a fault will be between two circuit conductors of the same source or between the circuit conductor and the equipment grounding conductor..."

I don't see anything in 110.10 about sources.

110.10 Circuit Impedance and Other Characteristics.
The overcurrent protective devices, the total impedance, the
component short-circuit current ratings, and other characteristics
of the circuit to be protected shall be selected and
coordinated to permit the circuit-protective devices used to
clear a fault to do so without extensive damage to the electrical
components of the circuit. This fault shall be assumed
to be either between two or more of the circuit conductors
or between any circuit conductor and the grounding conductor
or enclosing metal raceway. Listed products applied
in accordance with their listing shall be considered to meet
the requirements of this section.

Since as you will see none of the spliced grounding conductors are even bonded to the enclosure or together

250.148 requires the conductors to be bonded to the box if the circuit conductors are spliced in the box.

I am not sure what the difference in potential is for each one of these ground wires. Yes they are combined systems back at the 4000 amp service, but separated thereon from the main electrical room.

The fact that these circuits come through different electric meters does not change anything.