Tip – Latitude and Longitude on Large Scale Plans 

By on

If you are working on a large plan, get the real coordinates [latitude, longitude] for two or more points and add them to the drawing.  That way you can always work out the scale and dimensions.

I know that drawings have scales, grids etc. on them and they are supposed to work.  However, many times I've come across drawings where things don’t tie up.  There can be hundreds of reasons – mix-ups as drawings are moved between different parties, human errors in CAD, messed units,  printing problems, etc.  Having just spent a few hours sorting out the latest wrongly scaled drawing that’s come across my desk, I thought it would be helpful to pass on this tip.

As a bit more general information, we have the following:

Understanding:  latitude are parallel lines running North and South of the equator. Longitude are vertical lines running West or East from the Greenwich prime meridian (located just outside London).  Distance between lines of latitude are approximately equal (minor variances due to the shape of the earth.  Between lines of longitude the distance is greatest at equation and the lines converge at the poles.

Presentation: latitude and longitude can be presented in degrees, minutes, seconds or decimal degrees.  To mark coordinates using degrees, minutes, seconds - it is generally accepted that the latitude should be written first followed by longitude.  The latitude degrees should be two digits and the longitude three digits (i.e. 08°14’16” 128°34’32”).  Designations N, S, W or E are not required, although often used.

Accuracy: when using on site plots, make sure you have sufficient accuracy in the coordinates (this will usually mean two or more decimal places on the seconds).  One second of latitude is approximate equal to 30 M.  One second of longitude is approximately equal to 30 M at the equation, moving to zero at the poles.

Image reproduced from Wikipedia (http://en.wikipedia.org/wiki/File:Latitude_and_Longitude_of_the_Earth.svg),
access 04 October 2011



Steven McFadyen's avatar Steven McFadyen

Steven has over twenty five years experience working on some of the largest construction projects. He has a deep technical understanding of electrical engineering and is keen to share this knowledge. About the author

myElectrical Engineering

comments powered by Disqus



Bows and Arrows

It starts with me reading one of the Horrible History books with my son (Groovy Greeks). Arrows were mentioned which lead to the discussion of the bodkin...

Frame Leakage Protection

While not as popular as it once was, frame leakage protection does still have some use in some circumstances.  In essence frame leakage is an earth fault...

Low Voltage Circuit Breakers

Circuit breakers are switching devices whose primary function is to isolate parts of an electrical distribution system in the even of abnormal conditions...

A mechanical engineering paper, some history and memories

I was digging in my bookshelf and came across the 80th Anniversary Association of Mine Resident Engineers, Papers and Discussions Commemorative Edition...

How Electrical Circuits Work

If you have no idea how electrical circuits work, or what people mean then they talk about volts and amps, hopefully I can shed a bit light.  I’m intending...

Variable Frequency Drive

Variable frequency drives are widely used to control the speed of ac motors.  This note looks at the mechanisms which enable drive units to control the...

IEC 60287 Current Capacity of Cables - Rated Current

In the previous note we looked at the approach taken by the standard to the sizing of cables and illustrated this with an example.  We then looked at one...

Calculating Cable Fault Ratings

When selecting a cable, the performance of the cable under fault conditions is an important consideration. It is important that calculations be carried...

Autonomous Vehicle Challenge

Two driverless and solar power vans have departed from Italy on their way to China via the silk road. During the 13,000 kM trip the vans will drive themselves...

Nikola Tesla

Nikola Tesla was born exactly at midnight on July 10, 1856 in the tiny village of Smiljan, Lika in Croatia. In his late teens, Tesla left the village to...

Have some knowledge to share

If you have some expert knowledge or experience, why not consider sharing this with our community.  

By writing an electrical note, you will be educating our users and at the same time promoting your expertise within the engineering community.

To get started and understand our policy, you can read our How to Write an Electrical Note