Check your circuit breaker connections!

[rhino]

I've had my system installed for over 10 years and when I went to make some changes on the AC side I discovered many of the copper stranded wires were now loose in the breaker. The AC out from the inverter even fell out after touching it. So check the tightness/torque if it's been a while! Image below is the type I have.

 

[MurphyGuy]

Aluminum wire is most known for doing that.. pretty rare for copper if it was installed properly. But good advice to always give a system a tune up and check.

 

[HRTKD]

I wonder if the same problem would occur if ferrules had been used. I used ferrules where I could, but not every component could use them.

Anyhow, thanks for the tip. My RV trailer will see some rough roads. I need to add an annual reminder to myself to tighten everything up.

 

[rhino]

Actually I was thinking exactly that... if ferrules would have prevented it. It was only the THHN stranded wire that had the issue. I had some solid wire that was still tight.

 

[Hedges]

I've found that stranded wire doesn't get tight initially. The spec'd torque isn't enough to crush wire the way a crimp does.
What I've taken to doing is wiggling the wire back and forth while continuing to tighten the screw. It settles quite a bit.

 

[MurphyGuy]

Actually I was thinking exactly that... if ferrules would have prevented it. It was only the THHN stranded wire that had the issue. I had some solid wire that was still tight.

Stranded wire needs to be contained so it doesn't mash outward from the compression screw. Manufacturers set wire-gauge size tolerances on their products to prevent excessive.. err.. "mash out" for lack of a better term. If you're on the high side of those specs and the wire fills the cavity, ferrules wouldn't help any.. but if you're on the lower side, say you're sticking a 6ga wire into a terminal that goes from 6 to 1 gauge, then a ferrule would absolutely help.

I'm no wire expert, but I think THHN is an insulation spec, not a spec on the copper inside.

For fine stranded wires like battery cable, ferrules are almost mandatory.

 

[rhino]

The breakers shown don't have a compression screw but pulls the entire flat surface of the connection inside of the breaker up against the wire so it isn't as bad a a screw... but yes, appears it is a result of "mash out" and would think a ferrule would help in that case even though this isn't fine stranded copper.. think it is either 7 or 9 strands for 8 AWG.

 

[HaldorEE]

For solid wire, I am a firm believer in PM'ing screw terminals. Install them tight, then come back 48 hours later and tighten them again. It is rare you can't get more out of them after the wire has had a chance to relax under the screw.

Each time a wire is heat cycled it expands and contracts. This can result in loose connections.

That is one advantage to spring loaded terminal. They don't loosen up over time. Not great for high amps so I only use spring loaded terminals for low current circuits.

 

[WYtreasure]

Great suggestion.

 

[12VoltInstalls]

I wonder if the same problem would occur if ferrules had been used. I used ferrules where I could, but not every component could use them.

Anyhow, thanks for the tip. My RV trailer will see some rough roads. I need to add an annual reminder to myself to tighten everything up.

I think there is a potential for loosening over time whenever there’s a screw/bolt connection that isn’t required to be tightened to the torque specs of the fastener if it were ‘stretched’ by proper torque for a mechanical load.

I’ve had ferrules I’ve installed to my satisfaction feel inadequately tightened after a period of time. I don’t know about breakers, but a lot of electrical connector screws and bolts for stuff do have an inch-pound spec in their instruction sheet. Not clear if that insures tightness is maintained over time with an 10-32 screw or whatever.