Figuring conduit routings

[Alwayslearningelec]

If there is a large floor with a few corridors and 30-40 rooms and you run feeders from a central electrical room on the floor to various locations on he floor how do estimators determine the routing? What I mean is do you lays follow the coridoors or can you cut through rooms etc. what determines the route you would use? I am referring to new construction. Thanks

 

[infinity]

You said run feeders to several locations on the floor, are they feeding panels or are you really referring to branch circuits for lighting and power?

 

[John120/240]

what determines the route you would use? I am referring to new construction. Thanks

The shortest distance between two points is a straight line. With that said.......obstructions,

ductwork, plumbing pipes, sprinkler pipes etc. Who gets their stuff up in the air first ? Are all

of the trades working together ?

 

[Alwayslearningelec]

You said run feeders to several locations on the floor, are they feeding panels or are you really referring to branch circuits for lighting and power?

No feeders feeding panels

 

[Alwayslearningelec]

The shortest distance between two points is a straight line. With that said.......obstructions,

ductwork, plumbing pipes, sprinkler pipes etc. Who gets their stuff up in the air first ? Are all

of the trades working together ?

Yes, but how do you determine that in the estimating phase? As far as I know the electrician is one of the last people on the coordination list.

How do walls come into play? If it is a block wall floor to ceiling than i assume the electrician would have to chop through or would a slot/hole be created for them during the construction or would you not even route the conduits through that wall? Thanks

 

[iMuse97]

Yes, but how do you determine that in the estimating phase? As far as I know the electrician is one of the last people on the coordination list.

How do walls come into play? If it is a block wall floor to ceiling than i assume the electrician would have to chop through or would a slot/hole be created for them during the construction or would you not even route the conduits through that wall? Thanks

All conduit is run in straight lines parallel or perpendicular to walls and ceilings. Typically also MC. Firewalls get holes with firestop of some kind, and the installers avoid structural members. Actual route of conduit (or whatever) is determined onsite, by installing electricians.

 

[Alwayslearningelec]

All conduit is run in straight lines parallel or perpendicular to walls and ceilings. Typically also MC. Firewalls get holes with firestop of some kind, and the installers avoid structural members. Actual route of conduit (or whatever) is determined onsite, by installing electricians.

But sometime you have to cut across room and directly through a wall.....

 

[Strathead]

I am an experienced Estimator. I was estimating during the good years and right on through the last few. Estimating is done using two main criteria. WAG's (wild ass guesses) and SWAG's (scientific wild ass guesses). I tell you this so you understand that there is no one way to answer your question. However, I will always try to get big feeders routed as close as possible to what I figure is the likely installation path. Even larger is a variable term. A #1 feeder in EMT is not big on a 2 million dollar job, but it is big on a $20,000 job. Don't get too hung up on the details, but don't ignore them either. Many people will tell you that your take off should be the same regardless of economic conditions. I tend to agree to a certain extent, but if you are estimating for someone else, I think you may need to influence your numbers. I worked for a guy who would cut everything to the bone and then jump on me for every coupling I missed. So I had to make sure that his cuts would not cut in to losing the job. He was not an Electrician by the way, just a Business owner. I have also worked for someone who's own estimates are less detailed than mine. He tends to add a fudge factor in every estimate. If I ever want to get a bid, In must leave a littel less detail in my take off. All that said, I always take off my big feeders as closely as possible to actual, including junction boxes and 90's

 

[ritelec]

Not to be getting off topic here........

I've run many circuits and feeders in the "industrial,municipal,commercial,residential" veins. Above ground and below ground.

My question, have any of you had concerns with derating (ampacity adjustment) for buried runs?

Reason I ask is on all the installs, it was never an issue........except once, I came in on a job (goldman sachs), all the feeders where in the ground. Most of the feeders stayed (below grade), but some had to be re piped in the building
and those feeders below grade where either removed or abandoned.

$$$ ouch.

 

[renosteinke]

How to run the conduit? Well ....

In a perfect world, all your pipe would be run where nothing would ever damage it, it would always be easy to access, and the very few bends would be gentle. For that matter, the bends would be arranged so that you'd be pulling 'down' rather than 'up.'

Note how those desires conflict.

Run the pipe where it's out of the way and accessible ... the result is a bank of runs under the middle of the hall. Doing that, though, means there will be another 90 degree bend where they turn into the room - and that part of the run will be under a wall, which makes it a target for the framers.

 

[Smart $]

But sometime you have to cut across room and directly through a wall.....

A matter of planning, and attempting to work with the brickies. If at all possible run feeder conduits before wall is topped. On-site coordinator should be aware of when this occurs as boxes and conduit is typically installed as the wall is erected. If not possible, plan for installing sleeves. And worst case scenario, "bust" a hole.

 

[Smart $]

If there is a large floor with a few corridors and 30-40 rooms and you run feeders from a central electrical room on the floor to various locations on he floor how do estimators determine the routing? What I mean is do you lays follow the coridoors or can you cut through rooms etc. what determines the route you would use? I am referring to new construction. Thanks

Routing is as much an art as is estimating ...

First priority, run as much conduit as you can on the same rack(s) or trapeze(s) and branch off squarely as needed to keep the runs as short as squarely possible. Hindrances, such as masonry walls already erected, will cause variances to the program... :roll:

 

[stevenje]

Take the time to understand how and most importantly where the other trades are installing their systems. On many jobs working space is at a premium. Try and built a good working relationship with the other trades. It will pay off in spades.

 

[Strathead]

Did I miss the question, or has this thread deviated from the topic? I understood the OP to be asking how to estimate a conduit run, not how to lay it out or run it. That becomes a question of how deeply to delve in to the job conditions, not a discussion on how to run the conduit. I mean, come on, you could theorize that the purlins are 6 feet apart, so the run perpendicular to the purlins requires a strap every 6 feet, and the parrallel runs require a strap every 10 feet, but you have a run 6 feet down the wall that requires a different type of strap, and it runs through 2 walls that means you get to eliminate 2 straps................................ You get my point. Again, I have been doing it for a long time. I SWAG it, the OP is obviously just starting, so he definitely can only WAG it.

 

[cdslotz]

I think the OP is asking is how do you determine routing as it pertains to the estimate.
Since feeders are such a big ticket item, it is important to consider the routing of each feeder on the one-line.
If the structure is 1 or 2 stories and wide open, there's not much more it than measuring lengths at right angles, up's and downs, elbows and pull boxes.
When the structure is vertical, you have to consider your pathways up through the structure, stair wells, rest rooms, elevator shafts, ceilings open to the floor below, that you cannot route through. Some structures may have a switchboard in the basement or parking garage, with panels right above the switchboard, but you may have to route 50' to a vertical pathway and back to get to that panel.
As long as the total lengths are correct after all of that, then the estimate should be accurate. How it is run in the field can still vary but the cost should be covered. And if you're lucky, if you win the bid, once you dig into the job in detail, you may find better routings in your favor

 

[Alwayslearningelec]

I am an experienced Estimator. I was estimating during the good years and right on through the last few. Estimating is done using two main criteria. WAG's (wild ass guesses) and SWAG's (scientific wild ass guesses). I tell you this so you understand that there is no one way to answer your question. However, I will always try to get big feeders routed as close as possible to what I figure is the likely installation path. Even larger is a variable term. A #1 feeder in EMT is not big on a 2 million dollar job, but it is big on a $20,000 job. Don't get too hung up on the details, but don't ignore them either. Many people will tell you that your take off should be the same regardless of economic conditions. I tend to agree to a certain extent, but if you are estimating for someone else, I think you may need to influence your numbers. I worked for a guy who would cut everything to the bone and then jump on me for every coupling I missed. So I had to make sure that his cuts would not cut in to losing the job. He was not an Electrician by the way, just a Business owner. I have also worked for someone who's own estimates are less detailed than mine. He tends to add a fudge factor in every estimate. If I ever want to get a bid, In must leave a littel less detail in my take off. All that said, I always take off my big feeders as closely as possible to actual, including junction boxes and 90's

Thanks Strat. That is my question...what is the likely installation/routing? At there rules of thums when laying out etc.?

 

[Alwayslearningelec]

How to run the conduit? Well ....

In a perfect world, all your pipe would be run where nothing would ever damage it, it would always be easy to access, and the very few bends would be gentle. For that matter, the bends would be arranged so that you'd be pulling 'down' rather than 'up.'

Note how those desires conflict.

Run the pipe where it's out of the way and accessible ... the result is a bank of runs under the middle of the hall. Doing that, though, means there will be another 90 degree bend where they turn into the room - and that part of the run will be under a wall, which makes it a target for the framers.

Thanks

 

[Alwayslearningelec]

Routing is as much an art as is estimating ...

First priority, run as much conduit as you can on the same rack(s) or trapeze(s) and branch off squarely as needed to keep the runs as short as squarely possible. Hindrances, such as masonry walls already erected, will cause variances to the program... :roll:

Now that sounds good. Thanks

 

[Alwayslearningelec]

Did I miss the question, or has this thread deviated from the topic? I understood the OP to be asking how to estimate a conduit run, not how to lay it out or run it. That becomes a question of how deeply to delve in to the job conditions, not a discussion on how to run the conduit. I mean, come on, you could theorize that the purlins are 6 feet apart, so the run perpendicular to the purlins requires a strap every 6 feet, and the parrallel runs require a strap every 10 feet, but you have a run 6 feet down the wall that requires a different type of strap, and it runs through 2 walls that means you get to eliminate 2 straps................................ You get my point. Again, I have been doing it for a long time. I SWAG it, the OP is obviously just starting, so he definitely can only WAG it.

Hmmmmmm

 

[Alwayslearningelec]

I think the OP is asking is how do you determine routing as it pertains to the estimate.
Since feeders are such a big ticket item, it is important to consider the routing of each feeder on the one-line.
If the structure is 1 or 2 stories and wide open, there's not much more it than measuring lengths at right angles, up's and downs, elbows and pull boxes.
When the structure is vertical, you have to consider your pathways up through the structure, stair wells, rest rooms, elevator shafts, ceilings open to the floor below, that you cannot route through. Some structures may have a switchboard in the basement or parking garage, with panels right above the switchboard, but you may have to route 50' to a vertical pathway and back to get to that panel.
As long as the total lengths are correct after all of that, then the estimate should be accurate. How it is run in the field can still vary but the cost should be covered. And if you're lucky, if you win the bid, once you dig into the job in detail, you may find better routings in your favor

Thanks.