Line Side Tap

[Fitzdrew516]

I need to utilize a line side tap off existing gear to a new MCB panel (less than 10 ft. away) in order to obtain more capacity out of the existing gear. I've always seen this done by using a line side tap section paired on to the existing gear. The issue is that I have no space to add a section to the gear. So my question is ... Can this be done without using a new section of gear or no?

Thanks,
-Drew

 

[augie47]

Legal, but the devil may be in the details.
Items to consider: Total load on the conductors, of course
312.6 & 312.7
Your taps will need to be tapped from all conductors per phase. If you are
tapping a parallel feed you can't just tap one of the conductors.

 

[ron]

Legal, but the devil may be in the details.
Items to consider: Total load on the conductors, of course
312.6 & 312.7
Your taps will need to be tapped from all conductors per phase. If you are
tapping a parallel feed you can't just tap one of the conductors.

And the grounding conductor, if an actual conductor and not metallic raceway, must be sized based on the main breaker of the existing gear.

 

[Fitzdrew516]

Legal, but the devil may be in the details.
Items to consider: Total load on the conductors, of course
312.6 & 312.7
Your taps will need to be tapped from all conductors per phase. If you are
tapping a parallel feed you can't just tap one of the conductors.

Thanks for the reply. I get what you're saying as far as tapping parallel sets, etc, but is there no physical way to tap off the vertical bussing of the existing gear? So what the service looks like now is from the utility to an ATS with a 1600A MCB (service disconnect) then from there the parallel sets poke through the wall and serve the switchgear (6 disconnect setup was previously the service disconnect before the generator/ATS was added).

Forgive my ignorance as I have never designed something like this. I just sit at a desk and crunch numbers (engineer) :huh:

-Drew

 

[GoldDigger]

If one main breaker feeds two vertical bus sets, those buses would be electrically in parallel but would not be considered parallel conductors under the NEC because they do not come back together to feed a common point.
You could tap only one of them just as you can connect a bucket to one set of buses only.

 

[electrofelon]

I need to utilize a line side tap off existing gear to a new MCB panel (less than 10 ft. away) in order to obtain more capacity out of the existing gear. I've always seen this done by using a line side tap section paired on to the existing gear. The issue is that I have no space to add a section to the gear. So my question is ... Can this be done without using a new section of gear or no?

Thanks,
-Drew

The issue is how to attach the new set of service entrance conductors if there does not happen to be spare lugs on there for you to use. Since there are almost certainly 4 or more sets of conductors feeding the existing gear, it would be quite convoluted to tap onto those, and of course that would likely be out anyway if the metering is not at the transformer. What would be nice is if you can add on some new lugs, or change out the existing ones for ones that have more ports (again assuming this wouldnt put you ahead of the CT's). I recently had a situation on a 1200A square D switchboard where I needed to add another set of conductors for another service disconnect. Fortunately the bolt pattern at a bus bar transition was a standard NEMA 4 hole pattern so I was able to bolt on some Ilsco lugs.

 

[electrofelon]

And the grounding conductor, if an actual conductor and not metallic raceway, must be sized based on the main breaker of the existing gear.

Ron i dont understand this, can you expand on/clarify that?

 

[Smart $]

Thanks for the reply. I get what you're saying as far as tapping parallel sets, etc, but is there no physical way to tap off the vertical bussing of the existing gear? So what the service looks like now is from the utility to an ATS with a 1600A MCB (service disconnect) then from there the parallel sets poke through the wall and serve the switchgear (6 disconnect setup was previously the service disconnect before the generator/ATS was added).

Taking stabs at presenting you with a compliant solution depends on details... and you're not giving us much to go on. With each post we get more detail, and the possible solutions get better. So I have to wonder how many posts before we get all the pertinent details???

Starting at the ATS, please describe downstream equipment in detail, to and including the gear. That also includes sets of conductors, sizes, types, grounding, taps, gear manufacturer, bus ratings, ocpd ratings, taps, calculated load... practically anything that has a name with respect to anything that conducts electricity.

Pictures help on occasion, too...!!!

 

[ron]

Ron i dont understand this, can you expand on/clarify that?

If the line side is protected at 1600A from an upstream breaker, and you tap something smaller, such as 200A (10' tap) ..... Although your ungrounded conductors may be sized at 200A, the equipment grounded conductor, if not solely the EMT but you add a actual EGC conductor in the raceway, it needs to be sized per 250.122(G) at 4/0 Cu or 350kcmil AL, depending on you conductor selection.

 

[Fitzdrew516]

Taking stabs at presenting you with a compliant solution depends on details... and you're not giving us much to go on. With each post we get more detail, and the possible solutions get better. So I have to wonder how many posts before we get all the pertinent details???

Starting at the ATS, please describe downstream equipment in detail, to and including the gear. That also includes sets of conductors, sizes, types, grounding, taps, gear manufacturer, bus ratings, ocpd ratings, taps, calculated load... practically anything that has a name with respect to anything that conducts electricity.

Pictures help on occasion, too...!!!

See attached pictures. The two provisions in the pictures will be used as well, I just need more than I can get from them. The issue with information is this is out of state and this is the information I have been given. I realize someone may have to go on site to figure it out, but I'm hoping to be able to get this wrapped up as easily as possible.

 

[david luchini]

If the line side is protected at 1600A from an upstream breaker, and you tap something smaller, such as 200A (10' tap) ..... Although your ungrounded conductors may be sized at 200A, the equipment grounded conductor, if not solely the EMT but you add a actual EGC conductor in the raceway, it needs to be sized per 250.122(G) at 4/0 Cu or 350kcmil AL, depending on you conductor selection.

If your 200A tap conductors are 3/0 CU or 250 kcmil AL, then the EGC conductor would only have to be 3/0 CU or 250kcmil AL.

 

[kwired]

See attached pictures. The two provisions in the pictures will be used as well, I just need more than I can get from them. The issue with information is this is out of state and this is the information I have been given. I realize someone may have to go on site to figure it out, but I'm hoping to be able to get this wrapped up as easily as possible.

From external view - there appears to be at least room for one more breaker there.

Whether you can add a breaker or not, what is the load on the existing supply conductors and what do you intend to add for load?

 

[Smart $]

See attached pictures. The two provisions in the pictures will be used as well, I just need more than I can get from them.

Still short on detail... :roll:

What does the large frame space max out at per manufacturer?

How much do you need?

How much is already there?

You have to know these to say, "...I just need more than I can get from them".

The issue with information is this is out of state and this is the information I have been given. I realize someone may have to go on site to figure it out, but I'm hoping to be able to get this wrapped up as easily as possible.

Which state?

Cincinnati is but a stone's throw from Indiana and Kentucky. I usually cross multiple state lines when I go to work. For my most common work locations, I actually go through Cincinnati.

Anyway, external views do not help when talking taps.

PS: ATS/generator guys forgot to remove the service disconnect stickers.

 

[kwired]

From external view - there appears to be at least room for one more breaker there.

Whether you can add a breaker or not, what is the load on the existing supply conductors and what do you intend to add for load?

I now see that you maybe want to add more then the space I mentioned allows for - still am asking for existing load plus new load though.

 

[kwired]

If there is capacity to make the tap but difficulty finding a way to do it within that gear, maybe consider somehow tying into the line between the ATS and this gear? Probably not the simple answer you may be looking for.

 

[Smart $]

...
PS: ...

PPS: That panelboard looks to have a working space violation... even with the floor clutter removed.

 

[ADub]

PPS: That panelboard looks to have a working space violation... even with the floor clutter removed.

Are you thinking he should fix that existing violation or just pointing it out?


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[Fitzdrew516]

Still short on detail... :roll:

What does the large frame space max out at per manufacturer?

How much do you need?

How much is already there?

You have to know these to say, "...I just need more than I can get from them".


Which state?

Cincinnati is but a stone's throw from Indiana and Kentucky. I usually cross multiple state lines when I go to work. For my most common work locations, I actually go through Cincinnati.

Anyway, external views do not help when talking taps.

PS: ATS/generator guys forgot to remove the service disconnect stickers.

The job is north of Philadelphia so not very close

I'm going to need all of the 1600A. The existing demand on the service is 300ish amps. I then am feeding 800A out of the bottom provision (that's the max I've been told by Eaton) and then taking another 200A from the top provision. I don't have very many continuous loads or any other diversity really so 100% rated breakers won't really help me all that much (If the equipment is even listed to be used with 100% breakers). The calculated load on the new 800A feed is already over 800A and I've only connected most of the "large loads" (refrigeration, big equipment, etc.). The mechanical engineer still doesn't have information on the chiller so that load hasn't been added yet (hoping to use the 200A provision for that load).

So right now I'm already over what I can take and I still have a lot of equipment to add so it's safe to say I'm going to need more from that gear (800+200+ (300*1.25) = 1375. 1600-1375 = 225A extra that I can pull off the gear. This is only a 40% set to get an idea of pricing, but with the way it looks this could be a MAJOR cost changer down the road (i.e. potentially a new service) so I'me trying to do what I can to get this worked out before drawings need to go out the door.

- Drew

 

[Fitzdrew516]

Are you thinking he should fix that existing violation or just pointing it out?


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There may be one piece of electrical equipment in this whole plant that has proper clearance. I was told to leave it alone until told otherwise by an AHJ. We'll see how that goes

 

[kwired]

Clearance issues may not help here but outside of that it may be easier to replace that gear with something that suits your needs.