The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!


2017 NEC and Related
2017 NEC
Now Available!

Recent Posts
Parking lot pole light swap....
by gfretwell
10/24/16 08:46 PM
International Wire Colour Codes
by Tjia1981
10/23/16 12:08 PM
Son of Sparky
by HotLine1
10/20/16 07:43 PM
Speaking of Plugmold ...
by gfretwell
10/17/16 02:37 PM
Broken battery charger? Check for cobwebs!
by gfretwell
10/17/16 02:30 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 14
HotLine1 7
ghost307 7
renosteinke 6
Potseal 4
Who's Online
1 registered (HotLine1), 58 Guests and 8 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#214048 - 09/25/14 11:21 PM Water tank de-icer - panel is 500-600' from tank
Potseal Offline

Registered: 02/23/13
Posts: 191
Loc: Saskatchewan
I was asked today about the requirements for powering a 1500W 120V livestock water tank de-icer that was 500-600ft away from the panel. First thought that came to mind was "sub-panel". At that distance is it even reasonable to run conductors straight to the heater? At 500' and using a 3% voltage drop I ended up with #4 Cu (75 degree Celcius column Table 2 CEC). Wouldn't a small sub-panel placed closer to the tank and then running smaller gauge conductors to the heater be a better idea?
A malfunction at the junction

2014 / 2011 NEC & Related Books and Study Guides
#214051 - 09/26/14 06:44 AM Re: Water tank de-icer - panel is 500-600' from tank [Re: Potseal]
HotLine1 Online   content


Registered: 04/03/02
Posts: 6792
Loc: Brick, NJ USA

Vd for the load in the subpanel would be equal to what you calc'd for just the load.

IF you ran 3 wire & grd to the sub, you would have available 'load' capacity at the area.

Depending on available voltages at a source, 480 volt to the location, and a small 480-120 transformer may be economical.

#214053 - 09/26/14 10:52 AM Re: Water tank de-icer - panel is 500-600' from tank [Re: Potseal]
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Potseal, you are under a misconception.

What limits voltage drop issues to branch conductors alone? Circuit or panel - you need to allow for voltage drop. Only a higher voltage will lessen your voltage drop.

Set the 'percentage rule' aside for the moment. What's your final voltage when the heater is in use? If your incoming voltage is on the high side (127V is not all that rare), then you could very easily have a very acceptable 118V at the heater.

Whether you should set a panel is another question. I'm biased in favor, for two reasons.
First, I like having an OCPD, GFCI, and disconnecting means close to the point of use.
Second, you almost always have a later desire to add a light, a service receptacle, whatever in the same area. Might as well pull a 4th wire and have a second circuit.

Run big pipe - pipe is cheap - and you can pull bigger wire later if you need it.

Finally ...don't have 480? Make it. Just use two transformers: one 'up' and one 'down.'

#214056 - 09/26/14 01:45 PM Re: Water tank de-icer - panel is 500-600' from tank [Re: Potseal]
Potseal Offline

Registered: 02/23/13
Posts: 191
Loc: Saskatchewan
Thank-you for the suggestions. I will definitely consider them as it could solve the distance issue.


After doing my own calculations I decided to look online to see if I could compare my results to other available information. Found this related chart as a result:

A malfunction at the junction


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals