I know I'm guilty of this. Very interesting. Will put this on my Spring list.
Stainless steel washers in electrical circuits
- Thread starter Scott B
- Start date
SS is not a good electrical or heat conductor. When a SS washer is placed between a connector and the power source, the increased resistance may/will cause overheating with a fire potential. Aside from that the heat generated, the SS causes a voltage loss which is basically wasted energy.
Placing a SS washer on top of the the terminal, between the terminal and the nut is OK as it is not part of the circuit. SS washers between terminals is not OK.
The shiny silver parts of terminal blocks and busbars are plated brass or copper and not SS.
Edit: When the original post first appeared on my browser the Calder video did not load, so I explained the reasoning. Now I see that it has appeared. If anything I said is not consistent with Calder then we all know who to listen to...
Placing a SS washer on top of the the terminal, between the terminal and the nut is OK as it is not part of the circuit. SS washers between terminals is not OK.
The shiny silver parts of terminal blocks and busbars are plated brass or copper and not SS.
Edit: When the original post first appeared on my browser the Calder video did not load, so I explained the reasoning. Now I see that it has appeared. If anything I said is not consistent with Calder then we all know who to listen to...
This is a problem in automotive stuff as well. I was taught this about stainless way back in high school when taking a class on home electrical, and figured it was the same in an automotive setting. Well I got a car in my bay one day with the problem of the alternator was not charging. Ok.. test… yup not charging… remove alternator and find SS washers on the charging post… hmm. Bench test turns out good, returned alternator to the vehicle with a single nickel washer above the nut, wouldn’t you know… it was charging again. I make a note on the work order that I found SS washers on the charging post and removed them. All is good. The car came back a week later with the same problem, and I once again found the same SS washers in the same place. The owner got mad at me when I removed them the first time. When I removed them again and then put a note that the SS washers were causing the problem the guy got really mad at me and said I had no clue what I was doing, the washers were preventing corrosion and not the problem. And he wanted his washers put back on. I refused to do this. My shop owner couldn’t convince this guy either, and we lost a customer… good riddance!
Well done!. Another excellent video on a very under-discussed topic. I wrote about this back in 2012 for Marinehowto.com as well.
https://marinehowto.com/battery-melt-down-narrowly-averted
Good post @Scott B
I'll just add that the fastening hardware should never be part of the conducting path, even copper. The ring terminal should be directly against the buss bar or fuse, there should not be any washer in between. Copper, obviously, conducts much better than stainless steel but will still present an unnecessary resistance. The terminal post, washers and nuts are not to be considered part of the electrical path.
I'll just add that the fastening hardware should never be part of the conducting path, even copper. The ring terminal should be directly against the buss bar or fuse, there should not be any washer in between. Copper, obviously, conducts much better than stainless steel but will still present an unnecessary resistance. The terminal post, washers and nuts are not to be considered part of the electrical path.
True. But the real reason is that if the fastner is in the circut and is a significantly different material it will heat and cool, stretch and shrink, and eventually either fail or become loose. Ideally, the clamping bolt has the same coefficient of thermal expansion as the eyes being clamped.
If the fuse terminal, battery terminal, and wire terminal are in contact, I imagine it doesn't matter what the washer under the nut is made of - could well be non-conducting, it's just there to help provide tension to the connection. I knew intuitively, and now objectively, that you shouldn't be putting washers of any kind between the load carrying conductors.
Good post, thanks!
Good post, thanks!
I knew this earlier and all my electrical connections are lead, copper, tin to lead, copper, tin.
But I just replaced all my chainplates and re-installed the bonding cables. Which violates the rules. Stainless guys to stainless chainplates to stainless bolts to copper bonding system to iron engine block to stainless prop shaft. Personally, I'm not worried about it. I figure the lightning will come down the mast and jump from the mast step to the depth transducer and blow a hole in my boat way below the waterline. While I'm installing said transducer under clear skies. Cuz that's how my luck seems to run.
But I just replaced all my chainplates and re-installed the bonding cables. Which violates the rules. Stainless guys to stainless chainplates to stainless bolts to copper bonding system to iron engine block to stainless prop shaft. Personally, I'm not worried about it. I figure the lightning will come down the mast and jump from the mast step to the depth transducer and blow a hole in my boat way below the waterline. While I'm installing said transducer under clear skies. Cuz that's how my luck seems to run.
Hey, if you want to go to copper stays and chainplates, let us know how it works out!
I think the message here is not that stainless shouldn't be used for washers and nuts that secure these connections, one just must make sure that there's no stainless in the circuit, i.e., in the path from battery to load.
The point is that ss should not be between the lug and battery, or lug and busbar or lug and fuse.. This article should help clear up any
confusion: https://marinehowto.com/battery-melt-down-narrowly-averted
Why not...
I think that's what I said.
Sorry you are correct ! I missed the word not...
Sorry you are correct and I missed the word not...I think that's what I said.
thks understand where they should not be used...thats an understood and common practise..
Is the washers and nuts that are included from places like blue sea etc. stainless or tinned?
If they are tinned where to buy?
Is the washers and nuts that are included from places like blue sea etc. stainless or tinned?
If they are tinned where to buy?
Whatever Victron uses for its lock washers is very magnetic, if that’s any consolation.
Many stainless steels are magnetic. Steel was the most complicated thing I studied in engineering school, bar none! There are a zillion varieties of steel, and their properties can be changed, quickly, in various processes.