Community Forums

Z Whitman · 08-06-2021, 09:55 AM

Can you help me figure out the cause of heat damage on these connections?

These breakers are part of a solar installation shown on the diagram below.

The circuit breaker on the left is a 15A, 150VDC between the PV array (660W, 33.94V) and the charge controller (Victron MPPT 100 / 50). The breaker on the right is 63A, 150VDC between the charge controller and Lynx distributor.
The 15A breaker (from PV) tripped a few times before I noticed this happening.

Could this be a bad connection? Or high current draw?
I assume I need to replace at least the 63A breaker, but what could be done to avoid this from happening again?

Thank you!

wolfe10 · 08-06-2021, 10:02 AM

Usual causes are loose connection and/or high amp draw.

This type of connections needs to be tightened annually. Just part of routine Preventive Maintenance.

A very common issue with ATS's.

Old-Biscuit · 08-06-2021, 10:58 AM

Loose connection.......

Hopefully you have some/enough slant in wire to remove/cut off and reinstall then TIGHTEN CB wire connector

twinboat · 08-06-2021, 11:14 AM

You should be using a 25 amp breaker in that position.

660 watts ÷ 34 volts = 20amps.

Talloaks · 08-06-2021, 12:01 PM

"
When it comes to electrical installations, perhaps one of the most violated sections of the National Electrical Code has been and continues to be proper torquing of electrical connections."

Here are some links on breaker torque specs.

https://www.se.com/us/en/faqs/FA128927/

https://e-hazard.com/electrical-conn...-requirements/

Also refer to Informative Annex "I" of the 2020 NFPA 70 (National Electrical Code).

Also note that many if not most breakers have the torque requirements on a label, or molded into the plastic body.