Can I cut or extend my load cell cable?

Can I cut or extend the length of cable from my load cell to my summing junction box?

Hardy Process Solutions recommends that you do not cut or extend your load cell cable. If you absolutely must extend your load cell cable to reach the summing junction box, you should add the same length to each load sensor on that weighing system.

The length of cable from your summing junction box to your controller can be anywhere from 1-1000 feet depending on the instrument being used. There is a separate answer in Web Tech addressing C2 cable length by controller and summing card type. See related answer titled "What is the maximum load cell cable length".

If your load cells are C2® capable and you want to extend the length from the load cell to the summing junction box you would want to use our recommended C2® cable, as the cable spec's are very important.  The load cells that did not need a longer cable length would still need to be lengthened to keep all load cell cable lengths the same. It is important that the C2® cable resistance be equal on all load cells. There is a limit of 50' of load cell cable on the Advantage line of load cells and still keep the C2® information inside the load cell. When the length is over 50 feet, the C2® module needs to be relocated to the end of the cable or separated and installed on the back of the controller or summing junction box. If you need this it would be a special for a separate C2® chip or extra cable lengths on a load sensor so the C2® is correctly placed according to the length of cable requested.

Hardy Process Solutions recommends that you DO NOT cut your ADVANTAGE® or ADVANTAGE LITE® load sensor cable, as your C2® accuracy will be affected and the warranty will be voided.  Cutting a combined ten feet of cable from an Advantage Load Sensors will change the overall resistance of the load sensor cable and cause a C2® error of 1 part in 5000. For every 5000 pounds placed on the load sensor, the reading will be 1 pound heavy.

THE FORMULA IS AS FOLLOWS:

Rc*2L/Rlc

Rc = Resistance of cable per foot
L = Length removed from cable
Rlc = Resistance of load sensor input

EXAMPLE:
Rc = 0.0102 ohms per foot for 20 gage copper wire
L = 10 foot
Rlc = 1000 ohm input resistance for Advantage load sensors

0.0102*(2*10) = 0.204
0.204/1000 = 0.0002 or 1 part in 5000

COMPARISON:

Cutting 10 foot of cable from a standard C2® load sensor with a 350 ohm input resistance will cause an error of 1 part in 1700. This is 3 times worse than with (1000 ohm) Advantage load sensor. The C2® error will be the same no matter how many C2® load sensors you use in your system.

Some of our weight controllers have a selectable gravity correction factor.  This small amount of cable length error could be corrected using the gravity correction feature.  But the better idea is to not cut the cables.  If the issue is excess cable and a mess, add a secondary box inline from the load cell cable runs to coil up the excess cable.  There is not much room  for excess cable inside the summing junction boxes sold by Hardy Process Solutions. 

The Hardy C2 certified cable from the junction box to the controller can be cut to length.  By using the sense lines and removing the sense jumpers, C2 calibration accuracy will not be affected.