Building service question. 3#3/0 from utility that goes into a electrical meter that then goes into a junction box with 4#3/0 and 1#3/0 into a 400AMP?

Cartoon1

Cartoon1

Senior Member
Location
Florida
Occupation
Electrical Engineer
Hello, my favorite community. I ran into a building a few days ago and its electrical setup confused me and seemed off. Trying to understand why they did it that way.....

You had a electrical meter outside that has utility cables coming from underground to it that was rated for 3#3/0 (200A) ------ Then the cables went into an interior disconnect box (in the room behind it) that was being used as a junction box when i opened it up. But in that junction box now there is 5#3/0 (400A), those 5#3/0 goes into the building main panel 4hot and 1 neutral that was rated 400A. Clearly they added cable sets to make the cables rated 400A for the panel at the meter, but why just 1 neutral wire? and why is there no ground wire? Is that code compliant when they did it in the older day? (this is an old building). I'm also not sure why they needed the junction box when they could of just ran the conduit to the main panel right next to it. See pics and riser below.

Thank you,

PXL_20250422_130538054.jpg
PXL_20250307_183743685.jpg
 
So it's parallel #3/0's for the ungrounded conductors and a single #1/0 for the neutral?
 
The "smaller conductors" on line side of meter is likely POCO supplied and/or maintained and they deemed the load is no more than those conductors can handle.

The wiring beyond there is covered by NEC and if you are going to put 400 amp overcurrent protection on it then you need 400 amps of conductor.

The grounded conductor does have a minimum size and can't be any smaller then the SSBJ requirement in any case, but also doesn't need to be any larger than the calculated neutral load it will supply. If there is a significant amount of straight 240 volt load on this service it is pretty reasonable there would never be a full 400 amps ever placed on the neutral conductor.
 
infinity said:
So it's parallel #3/0's for the ungrounded conductors and a single #1/0 for the neutral?
Click to expand...
Parallel 4#3/0 for ungrounded and i suspect 1#3/0 for the neutral (couldn't exactly read it on the neutral cable) but it looked the same size as the ungrounded cable.
 
Cartoon1 said:
Parallel 4#3/0 for ungrounded and i suspect 1#3/0 for the neutral (couldn't exactly read it on the neutral cable) but it looked the same size as the ungrounded cable.
Click to expand...
Okay not sure why I thought it had a #1/0 neutral but it doesn't matter. The neutral can be sized for the load so it may be small than the ungrounded conductors.
 
As long as the neutral is sized to carry the load (per 220.61) and not smaller than allowed by 250.24 (250.102( there should be no problem. As far as an equipment grounding conductor, one is not required when you are dealing with services as the neutral serves as the grounding conductor also.
(There does appear to be a violation as far as grounding as related to 250.92)
 
Is it just me or does the lack of bonding bushing and plastic conduit from the box to the right enclosure (main distribution panel?) seem like it needs fixing.
 
Elect117 said:
Is it just me or does the lack of bonding bushing and plastic conduit from the box to the right enclosure (main distribution panel?) seem like it needs fixing.
Click to expand...
The "pass through" box needs to be bonded to the grounded service conductor. It is possible, but unclear to me from the photo, that it is bonded to the meter enclosure via a metallic nipple that enters the back of the box, and the meter enclosure is bonded to the grounded service conductor. If those bonds comply with 250.92, there is no need for a direct bond between the pass through box and the service disconnect to its right.

Cheers, Wayne
 
wwhitney said:
The "pass through" box needs to be bonded to the grounded service conductor. It is possible, but unclear to me from the photo, that it is bonded to the meter enclosure via a metallic nipple that enters the back of the box, and the meter enclosure is bonded to the grounded service conductor. If those bonds comply with 250.92, there is no need for a direct bond between the pass through box and the service disconnect to its right.

Cheers, Wayne
Click to expand...

Or a SSBJ would work as well. I just don't think it meets it currently. Plastic bushing and no apparent bonding locknut. But who knows. Maybe there is something I just can't see.
 
infinity said:
That converted disconnect switch needs to be bonded directly to the neutral. The bonding of the service raceway is a separate requirement. That entire install is pure hack work.
Click to expand...
wwhitney said:
The "pass through" box needs to be bonded to the grounded service conductor. It is possible, but unclear to me from the photo, that it is bonded to the meter enclosure via a metallic nipple that enters the back of the box, and the meter enclosure is bonded to the grounded service conductor. If those bonds comply with 250.92, there is no need for a direct bond between the pass through box and the service disconnect to its right.

Cheers, Wayne
Click to expand...

You both used the word neutral / grounded conductor. Am I wrong in thinking a SSBJ would work?
 
Cartoon1 said:
Hello, my favorite community. I ran into a building a few days ago and its electrical setup confused me and seemed off. Trying to understand why they did it that way.....

You had a electrical meter outside that has utility cables coming from underground to it that was rated for 3#3/0 (200A) ------ Then the cables went into an interior disconnect box (in the room behind it) that was being used as a junction box when i opened it up. But in that junction box now there is 5#3/0 (400A), those 5#3/0 goes into the building main panel 4hot and 1 neutral that was rated 400A. Clearly they added cable sets to make the cables rated 400A for the panel at the meter, but why just 1 neutral wire? and why is there no ground wire? Is that code compliant when they did it in the older day? (this is an old building). I'm also not sure why they needed the junction box when they could of just ran the conduit to the main panel right next to it. See pics and riser below.

Thank you,

View attachment 2577005
View attachment 2577006
Click to expand...
2023 NEC TX
This gutted disconnect will not meet 2023 NEC to be used in lieu of a properly sized J&P BOX, 314.28
No, that's not per NEC.
That's not a pull box and/or junction box as describe by NEC. It does not meet wire deflection rules per NEC.
"Where is the ground wire"? Says you.
Do you mean the grounding electrode conductor?
So, it's a parallel now?
Need little more info.

TX+MASTER#4544
 
TX+ MASTER#4544 said:
That's not a pull box and/or junction box as describe by NEC. It does not meet wire deflection rules per NEC.
Click to expand...
It is a cabinet, or at least it was when it still had the guts in it. I don't believe there is any listing requirements for boxes in general, though there is some specific applications that require a box listed for that application. This is not one of those applications. AFAIK you can make you own junction/pull box for general use as long as it meets construction specifications in part IV of 314. This old cabinet likely meets those specifications or can fairly easily be modified to meet them.

I do agree that the two entries are too close to each other though.
 
2023 NEC TX
314.28 Pull and Junction Boxes and Conduit Bodies
Section 314.28 (A) Minimum Size. ........conductors larger than 4 AWG.........
314.28 ((1) Straight Pulls.... eight times.......
314.28 (2) Angel or U Pulls ......six times
It's still a Cutout Box by definition of Article 100
How can you modify that enclosure, just buy a new one that will meet the specifications.
Code says conductors 4 AWG or larger.
Thanks for reading
Comments accepted
TX+MASTER#4544
 
TX+ MASTER#4544 said:
2023 NEC TX
314.28 Pull and Junction Boxes and Conduit Bodies
Section 314.28 (A) Minimum Size. ........conductors larger than 4 AWG.........
314.28 ((1) Straight Pulls.... eight times.......
314.28 (2) Angel or U Pulls ......six times
It's still a Cutout Box by definition of Article 100
How can you modify that enclosure, just buy a new one that will meet the specifications.
Code says conductors 4 AWG or larger.
Thanks for reading
Comments accepted
TX+MASTER#4544
Click to expand...
Are you saying cutout boxes can't be used? None of the cutout boxes I bought for my jobs had KOs. They are always field punched.

The existing box could be made to work. However you would have to remove or cut the wires.
 
TX+ MASTER#4544 said:
2023 NEC TX
314.28 Pull and Junction Boxes and Conduit Bodies
Section 314.28 (A) Minimum Size. ........conductors larger than 4 AWG.........
314.28 ((1) Straight Pulls.... eight times.......
314.28 (2) Angel or U Pulls ......six times
It's still a Cutout Box by definition of Article 100
How can you modify that enclosure, just buy a new one that will meet the specifications.
Code says conductors 4 AWG or larger.
Thanks for reading
Comments accepted
TX+MASTER#4544
Click to expand...
Nothing wrong with using cabinet or cut out box. Distance between raceways still applies for any enclosure type and is the real code issue here, and possibly bonding issues we can't really see if it complies or not on that aspect.
 
Is there something in Article 312 saying that conductors passing through a cabinet or cut-out box without termination shall comply with 314.28? If not, I don't see how 314.28 is relevant to a cabinet or cut-out box.

Cheers, Wayne
 
wwhitney said:
Is there something in Article 312 saying that conductors passing through a cabinet or cut-out box without termination shall comply with 314.28? If not, I don't see how 314.28 is relevant to a cabinet or cut-out box.

Cheers, Wayne
Click to expand...
Isn't cabinet or cutout box generally intended to enclose other components like a panelboard or other similar items? Once you remove those items and do not intend to replace with a similar item haven't you effectively converted it to a junction or pull box?

312.6 - .7,.8 and .9 all have wiring space requirements. But if you remove the switches, overcurrent devices, etc... can you still not use the space they took up?
 
kwired said:
Isn't cabinet or cutout box generally intended to enclose other components like a panelboard or other similar items? Once you remove those items and do not intend to replace with a similar item haven't you effectively converted it to a junction or pull box?
Click to expand...
Good point, the scope of 314 refers to "all boxes and conduit bodies used as outlet, device, junction, or pull boxes." Box is not a defined term, unlike cabinet and cut-out box. So a cabinet or cut-out box used as a pull box is subject to Article 314.

Never mind.

Cheers, Wayne
 
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