1. Junior Member
Join Date
Feb 2007
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5

## Electrical Riser Diagram

I am an electrical design engineer for residential and commercial buildings. I started this job a week ago. Can some one help me understand what is electrical riser diagram?

Does anyone has sample PDF or DWG file which shows the electrical riser diagram?

I know how to size panel board and calculate wire sizes.

This will really help me in my job... Thank you so much in advance.

2. Member
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Mar 2003
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South Carolina
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Riser diagrams can mean different things, depending on who is requesting it. Bur generally, a riser diagram is a physical simple diagram of the system layout. For instance, you might show the main switchboard on a lower level with the incoming service from underground to outside to the pad mounted transformer. Out the top of the switchboard, would come your feeders to the individual panels on each floor or into each area. You may also show the conduit and conductor sizes, again depending on who is the requestor, and generally that is the plans checker, or the owner in the case of a large commercial project. Hope this helps.
Most times, the riser diagram gives pertinent information that a single line doesn't give, and it is easier for the checker to visualize the system layout by looking at a riser diagram.

3. Like many other terms and phrases in the design side of our industry, the phrase “riser diagram” will mean different things to different people. The phrase “one line diagram” shares this fate. It is often necessary to ask someone to clarify what they mean, when then use one of those phrases.

To me, the phrase “riser diagram” is a drawing that shows a building’s principle set of power sources (utility and local generators), switchgear, switchboards, transfer switches, transformers, distribution panels, and branch circuit panels. It differs from my notion of a “one line diagram” in two ways. One is that it does not show all circuit breakers. The other is that it conveys not only the connections (i.e., panel B gets power from panel A, and in turn provides power to panel C), but also gives relative locations.

Imagine a four story building. Take a sheet of paper and draw four horizontal lines (five, if you have equipment on the roof). Label them 1, 2, 3, and 4 (and R, if needed). Every major component on the first floor is depicted with a box (or other symbol) above line “1.” This may include the main service switchboard, a transformer or two, a distribution panel, and a few branch circuit panels. Each is shown as a box, and you connect them with lines. You may even include some indication of the type and size of feeders between boxes. I usually only show breakers on the main board and any distribution panels.

Suppose you have a 480/277V distribution panel, a 480-120/208V transformer, and a few 120/208V branch circuit panels on each floor. You would then put boxes on each “floor” of the diagram, depicting each component, and you would show the feeders that connect the boxes. I generally don’t see any branch circuit loads on a riser diagram. But I would show large loads, such as condensing units, as individual symbols on the riser diagram.

4. Junior Member
Join Date
Feb 2007
Posts
5
Thanks... it did help, I am gettin it.

The township, plan checker, requested the riser diagram.

Currently, I am working on an electrical design for 22 unit - 3 stories condo. I have shown the panel board for building and individual panel board for each dwelling unit but i believe township wants to see how i am bringing wires from electrical room, meter room, to each dwelling unit.

How should I size the conduit and conductors?

Thanks.

Originally Posted by sc57ford
Riser diagrams can mean different things, depending on who is requesting it. Bur generally, a riser diagram is a physical simple diagram of the system layout. For instance, you might show the main switchboard on a lower level with the incoming service from underground to outside to the pad mounted transformer. Out the top of the switchboard, would come your feeders to the individual panels on each floor or into each area. You may also show the conduit and conductor sizes, again depending on who is the requestor, and generally that is the plans checker, or the owner in the case of a large commercial project. Hope this helps.
Most times, the riser diagram gives pertinent information that a single line doesn't give, and it is easier for the checker to visualize the system layout by looking at a riser diagram.

5. Junior Member
Join Date
Feb 2007
Posts
5
Thanks charles...

Originally Posted by charlie b
Like many other terms and phrases in the design side of our industry, the phrase “riser diagram” will mean different things to different people. The phrase “one line diagram” shares this fate. It is often necessary to ask someone to clarify what they mean, when then use one of those phrases.

To me, the phrase “riser diagram” is a drawing that shows a building’s principle set of power sources (utility and local generators), switchgear, switchboards, transfer switches, transformers, distribution panels, and branch circuit panels. It differs from my notion of a “one line diagram” in two ways. One is that it does not show all circuit breakers. The other is that it conveys not only the connections (i.e., panel B gets power from panel A, and in turn provides power to panel C), but also gives relative locations.

Imagine a four story building. Take a sheet of paper and draw four horizontal lines (five, if you have equipment on the roof). Label them 1, 2, 3, and 4 (and R, if needed). Every major component on the first floor is depicted with a box (or other symbol) above line “1.” This may include the main service switchboard, a transformer or two, a distribution panel, and a few branch circuit panels. Each is shown as a box, and you connect them with lines. You may even include some indication of the type and size of feeders between boxes. I usually only show breakers on the main board and any distribution panels.

Suppose you have a 480/277V distribution panel, a 480-120/208V transformer, and a few 120/208V branch circuit panels on each floor. You would then put boxes on each “floor” of the diagram, depicting each component, and you would show the feeders that connect the boxes. I generally don’t see any branch circuit loads on a riser diagram. But I would show large loads, such as condensing units, as individual symbols on the riser diagram.

6. Junior Member
Join Date
Jan 2007
Posts
6
NEC art. 300, Annex C

7. Member
Join Date
Jan 2007
Posts
57
Hi neha101083,

The numeric labeling of the panels and devices apply to their circuit numbers in respect to the source panel board. With the sizing question you asked I would recommend looking at Volts from Dolphins Software. This program not only automatically draws your one line, panel schedules, feeder schedules, etc. but also sizes panels, conductors, conduits, cable trays, transformers, etc.

8. Senior Member
Join Date
Mar 2004
Location
Arizona
Posts
3,913
nehal101083,

These being 'Condo' units, the city may be interested in how you plan to

run the feeders to each unit without running them thru the space of other

peoples condo units.

9. Junior Member
Join Date
Feb 2007
Posts
5
Thanks all of you...

I checked NEC article 300 and it helps indeed.

I will download trial v. of dolphin sotware to see how it works...

Thank you guys.

10. Junior Member
Join Date
Apr 2006
Location
New York
Posts
7

## Example of riser diagram

The attached graphic represents a simple one-line riser diagram. Hope it helps!
Last edited by acvolts; 03-31-07 at 07:21 AM. Reason: manage attatchment

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