I have recently encountered what is either the worst example of workmanship in a PV installation or a strange phenomenon of nature and time.
The site in question had at least 50 MC4 terminations with 1+" of exposed copper between the wire insulation and the plastic connector (see images). These terminations were all located at the negative end of each string where the negative from the last module plugged into the negative source wire going to a junction box. None of the positive terminations had this issue. None of the connections inside the junction box or string inverter had this issue.
This was obviously an incredibly dangerous fire and safety hazard. The only explanations I can think of are:
1. Someone who was not trained and had no idea what they were doing was tasked with performing these terminations. Many of the crimps were also loose.
2. The negative source wire used has somehow contracted over time and pulled out of the MC4 connector to reveal exposed copper. It appears to be standard PV wire with equal ratings to the positive wire and all others used by this installer.
Neither seem very likely to me. Does anyone have any insight to this phenomenon or any other plausible theories?
Thank you!!
The site in question had at least 50 MC4 terminations with 1+" of exposed copper between the wire insulation and the plastic connector (see images). These terminations were all located at the negative end of each string where the negative from the last module plugged into the negative source wire going to a junction box. None of the positive terminations had this issue. None of the connections inside the junction box or string inverter had this issue.
This was obviously an incredibly dangerous fire and safety hazard. The only explanations I can think of are:
1. Someone who was not trained and had no idea what they were doing was tasked with performing these terminations. Many of the crimps were also loose.
2. The negative source wire used has somehow contracted over time and pulled out of the MC4 connector to reveal exposed copper. It appears to be standard PV wire with equal ratings to the positive wire and all others used by this installer.
Neither seem very likely to me. Does anyone have any insight to this phenomenon or any other plausible theories?
Thank you!!
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