sizing conductors

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JRCJ

Member
Could someone please explain to me how to size the conductors and conduit sizes for a new 1200amp service? Thank you.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
What kind of service? Single phase or three phase? Three wire or 4 wire? We need more information.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
knowledge

knowledge

rr said:
Shouldn't an Electrician know this?
rr,
come ride a day with any inspector on this forum and then ask that
 

haskindm

Senior Member
Location
Maryland
That does not change the question, "Shouldn't an electrician know this?"
The answer is that an electrician WILL know this, unfortunately there are people doing elecrical work that are not electricians! Just as there are people working on cars that are not mechanics, and people building houses that are not carpenters.
A person that would ask this type of question has no business anywhere near an electrical installation unless they are closely supervised.
 

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
JRCJ said:
Could someone please explain to me how to size the conductors and conduit sizes for a new 1200amp service? Thank you.

It might be more appropriate to post YOUR sizing calculations, and see if anyone is willing to give it a once over.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
At 1200A, there are a lot of variables. If you aren't comfortable sizing this yourself, I think you should be asking for the assistance of one of the engineers on this job (assuming there are any).

Steve
 

JRCJ

Member
Excuse me for asking.... I am just starting out as an Electrician and trying to learn. Yes I am supervised. For the people with the derogatory comments you can keep those to yourselves. Ask your self if you knew everything when you first started out?
 

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
No matter how much information that is provided, it will be unlikely that you will be able to do what you are asking. Infinity was polite in asking for the additional information, but it was not provided.

If you are just starting out as an electrician, it seems that sizing a 1200A service is rather a large task. Perhaps you should sit down with one of the journeymen who supervises you, and ask them to go over it. YOu may wnat to start a little smaller, i.e. like how to size a residential service, etc.
 

iwire

Moderator
Staff member
Location
Massachusetts
Personally I think we could have been a little more helpful, that is the intent of the forum....the sharing of knowledge.

I don't believe that every electrician must know where to start with a 1200 amp service.

It all depends on what you normally do, you might be the worlds best service electrician or residential electrician and never be called upon to work with feeders over 200 amps. Lets not shoot someone down for asking questions.


Now that said, JRCJ we are not going to be able to design a 1,200 amp service over the Internet, we can however give you some basic info if that is all your after.

Some basic questions need to be answered.

1) Do you have a calculated load of 1200 amps?

2) Copper or Aluminum?

3) Bus duct or conductors?

4) The questions Trevor asked.

5) Is a large portion of the load non-liner?

6) Is the distance from transformer to service long?

Right off the bat I could say run 3 sets of 600 copper or 3 sets of 750 aluminum and that might do it but if you would like to get specific you need to answer at least some of the questions.

Bob
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
haskindm said:
That does not change the question, "Shouldn't an electrician know this?"
The answer is that an electrician WILL know this, unfortunately there are people doing elecrical work that are not electricians! Just as there are people working on cars that are not mechanics, and people building houses that are not carpenters.
A person that would ask this type of question has no business anywhere near an electrical installation unless they are closely supervised.


Not all electricians design services. That doesn't make them less of an electrician. Many electricians are installers. They take the information off a set of prints and build the project. Many do that quite well but would be lost when it came to properly designing something. We shouldn't be insulting someone for simply asking a question. Just my 2 cents.
 

rr

Member
Location
Georgia
JRCJ said:
Excuse me for asking.... I am just starting out as an Electrician and trying to learn. Yes I am supervised. For the people with the derogatory comments you can keep those to yourselves. Ask your self if you knew everything when you first started out?
If you view it as a derogatory comment, I apologize.

However, I'm concerned about YOUR safety as well as those around you. I'm also concerned about the safety of Electricians that might be modifying and/or adding to your installation 20 years down the road.

We're all constantly learning. Heck, I learn new things from Electricians quite a bit. But if you don't know how to proceed on a certain installation, STOP. Ask your supervisor for their opinion on how to proceed. If they're not available, break open the NEC and try to narrow down some relevent information. If you can come up with some preliminary calculations to show us, that's even better.

Electricians are some of the smartest people in the industry. Show some initiative! :)
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
I didn't mean my comment to be derogatory in any way. Just some advice that you are free to take or leave as you please.

Actually, I think I should of made my statement a little more general. In most cases, I think an engineer should be involved in sizing wire for a 1200A service. I don't think electricians should be doing design work on a feeder this large (in most cases). In a lot of places, a drawing stamped by a PE would be required before getting a permit for this.

Of course, I may be biased, since I am an engineer.

Steve
 
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