Determining Wire Size for Electric Trolley Bus Power Supply

  • Thread starter Thread starter nikola-tesla
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around determining the appropriate wire size for an electric trolley bus power supply, specifically focusing on the calculations needed for wire gauge based on voltage, current, and distance from the power source. The conversation includes theoretical considerations, practical applications, and calculations related to electrical wiring standards.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant inquires about the wire size needed for a 15 Amp, 115 Volt appliance located 230 feet from the power source.
  • Another participant suggests using an online wire gauge calculator but notes it is only for 24 volt equipment.
  • Some participants mention typical household wiring sizes, suggesting AWG number 12 or 14, and reference various resources for wire gauge tables.
  • One participant proposes using #8 copper or #6 aluminum wire, discussing the implications of using larger wire sizes with a 15-amp circuit breaker and receptacle, raising concerns about compliance with electrical codes.
  • Another participant emphasizes the importance of allowing a maximum voltage drop of 5 volts in the circuit and provides a formula for calculating voltage drop, leading to a recommendation of #8 copper wire based on their calculations.
  • There is a reiteration of the voltage drop calculation, confirming the recommendation of #8 or 8.0 sqmm wire, while noting that this calculation may not apply to large motors due to their higher starting current requirements.
  • A later post expresses gratitude for the information received, indicating some level of understanding achieved.
  • A new participant introduces a project on electric trolley buses, seeking guidance on calculating proper wire size for various AC and DC voltages, indicating ongoing exploration of the topic.

Areas of Agreement / Disagreement

Participants express multiple viewpoints regarding wire size recommendations and calculations, with no consensus reached on a single approach or solution. There are competing suggestions and calculations presented, indicating an unresolved discussion.

Contextual Notes

Some calculations depend on specific assumptions about voltage drop limits and wire material (copper vs. aluminum). The discussion also highlights potential regulatory considerations regarding electrical code compliance.

Who May Find This Useful

This discussion may be useful for electrical engineering students, professionals involved in electrical installations, and individuals working on projects related to electric vehicles or power supply systems.

nikola-tesla
Messages
44
Reaction score
0
If specs on an appliance plate read ; 15 Amps, 115 Volts.
The distance from the power source to the receptacle (plug) where the appliance is going to be plugged is 230 feet, what is the wire (american wire gage) or conductor size, the thickness of the wire? Thank you.
 
Engineering news on Phys.org
You can check the distance you can go with this http://www.pelco.com/support/tools/wiregacalc.aspx

EDIT: Sorry. This calculator is for 24 volt equipment only!

Regards
 
Last edited by a moderator:
Typical household wiring is AWG number 12 or 14.

See if any of these of useful -

www.faa.gov/certification/aircraft/av-info/dst/43-13/Ch_11-05.doc[/URL] (open directly or save target as), which looks like it gives gauge 8 for 115 V, 240 feet, 15A - but check the Word document.

Wire gauge calculator - [url]http://www.powerstream.com/Wire_Size.htm[/url]

Electrical conductors
[url]http://www.tpub.com/content/neets/14176/index.htm[/url]
[url]http://www.tpub.com/content/neets/14176/css/14176_20.htm[/url] - Wire gauge table
 
Last edited by a moderator:
nikola-tesla said:
If specs on an appliance plate read ; 15 Amps, 115 Volts.
The distance from the power source to the receptacle (plug) where the appliance is going to be plugged is 230 feet, what is the wire (american wire gage) or conductor size, the thickness of the wire? Thank you.

Use #8 copper or # 6 aluminum. If the appliance has a 15-amp connector (plug) you must use a 15-amp circuit breaker and 15/20-amp receptacle. I am not sure a 15-amp breaker or receptacle exists that will allow connection to these large wire sizes so you’ll need to pigtail with short smaller gauge wire with approved mechanical devices. I'm not sure if doing that is allowed by the electrical code. If you use aluminum, all mechanical connection points must be approved for aluminum and must be coated with anti-oxidation paste. A # 8 copper cable may have to be special ordered in some areas and will be more expensive.

Some insurance companies will not reimburse for damage if the electrical code is not followed.




...
 
nikola-tesla said:
If specs on an appliance plate read ; 15 Amps, 115 Volts.
The distance from the power source to the receptacle (plug) where the appliance is going to be plugged is 230 feet, what is the wire (american wire gage) or conductor size, the thickness of the wire? Thank you.

USUALLY IF THE APPLIANCE IS RATED 115 VOLTS, ITS MINIMUM OPERATING VOLTAGE OR THE ACTUAL VOLTAGE MUST BE SUPPLIED BY THE OUTLET MUST NOT BE LESS THAN 110 VOLTS.

IN THIS CASE TO BE SAFE, WE MUST ALLOW A MAXIMUM VOLTAGE DROP OF 5 VOLTS IN THE CIRCUIT. TAKE A LOOK IN THE FORMULA BELOW...

VD= 2*K*I*L/ CSA

WHERE:

VD= VOLTAGE DROP
I= CURRENT
L= DISTANCE OF THE LOAD FROM THE OUTLET (IN FT)
K= 12 FOR COPPER AND 19 ALUMINUM (FOR MAXIMUM TEMP OF 75 DC)
CSA= CONDUCTOR CROSS SECTIONAL AREA IN CIRCULAR MILS.


***SUPPOSE WE USE COPPER CONDUCTOR AND WE ALLOW A MAXIMUM OF 5V MAX. VOLTAGE DROP:

5= 2*12*15*230/CSA

CSA= 82800/5

CSA= 16560 CM

FROM COMMERCIAL REFERRENCES:

15560 CM IS CLOSEST TO 16510 CM WHICH IS #8 COPPER OR 8 SQMM WIRE.

NOTE:

1. IN THIS CASE A MAXIMUM OF 5 VOLTS WAS CONSIDERED IN THE CALCULATION.

2. THIS CALCULATION IS NOT VALID FOR LARGE MOTORS. BECAUSE MOTORS DRAWS A MAXIMUM OF 7OO% TIMES ITS FULL LOAD TORQUE DEPENDING ON THE MOTOR CONTROL STARTING METHODS USED BY THE DESIGNING ENGINEER.
 
nikola-tesla said:
If specs on an appliance plate read ; 15 Amps, 115 Volts.
The distance from the power source to the receptacle (plug) where the appliance is going to be plugged is 230 feet, what is the wire (american wire gage) or conductor size, the thickness of the wire? Thank you.

USUALLY IF THE APPLIANCE IS RATED 115 VOLTS, ITS MINIMUM OPERATING VOLTAGE OR THE ACTUAL VOLTAGE MUST BE SUPPLIED BY THE OUTLET MUST NOT BE LESS THAN 110 VOLTS.

IN THIS CASE TO BE SAFE, WE MUST ALLOW A MAXIMUM VOLTAGE DROP OF 5 VOLTS IN THE CIRCUIT. TAKE A LOOK IN THE FORMULA BELOW...

VD= 2*K*I*L/ CSA

WHERE:

VD= VOLTAGE DROP
I= CURRENT
L= DISTANCE OF THE LOAD FROM THE OUTLET (IN FT)
K= 12 FOR COPPER AND 19 ALUMINUM (FOR MAXIMUM TEMP OF 75 DC)
CSA= CONDUCTOR CROSS SECTIONAL AREA IN CIRCULAR MILS.


***SUPPOSE WE USE COPPER CONDUCTOR AND WE ALLOW A MAXIMUM OF 5V MAX. VOLTAGE DROP:

5= 2*12*15*230/CSA

CSA= 82800/5

CSA= 16560 CM

FROM COMMERCIAL REFERRENCES:

15560 CM IS CLOSEST TO 16510 CM WHICH IS #8 COPPER OR 8 SQMM WIRE.


THEREFORE: USE #8 OR 8.0 sqmm WIRE.


NOTE:

1. IN THIS CASE A MAXIMUM OF 5 VOLTS WAS CONSIDERED IN THE CALCULATION.

2. THIS CALCULATION IS NOT VALID FOR LARGE MOTORS. BECAUSE MOTORS DRAWS A MAXIMUM OF 7OO% TIMES ITS FULL LOAD TORQUE DEPENDING ON THE MOTOR CONTROL STARTING METHODS USED BY THE DESIGNING ENGINEER.
 
Thanks to all of you, I got it now.
 
Hai
Iam rias iam doing my project on electric trolley bus which should be taking power supply from over head grid supply and running the vehicle through drive motors. In this case iam having various Ac & Dc voltages.
I need how to calculate the proper wire size in sqmm. please reply me as soon as possible with proper formulas. I have calculated all the terms as volt,amps,watt,res, ohms etc


Regards
A.Riaz ahamed
 

Similar threads

Replies
6
Views
4K
  • · Replies 4 ·
Replies
4
Views
4K
Replies
6
Views
3K
Replies
15
Views
2K
  • · Replies 1 ·
Replies
1
Views
7K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 16 ·
Replies
16
Views
4K
  • Sticky
  • · Replies 705 ·
24
Replies
705
Views
123K
Replies
6
Views
4K
  • · Replies 41 ·
2
Replies
41
Views
7K