mount busbars on wood ?
- Thread starter WoodsieLord
- Start date
Admittedly I only read half the answers.
When we build "backboards" for our telephone and signaling circuits we use fire rated plywood painted with fire retardant paint. The we mount all of our busbars, blocks, etc. onto that backboard.
Funny thing is we have to leave the square patch that shows the fire rating of the board unpainted for the inspector to see it.
Since all of our "stuff" is DC voltage. Mostly 48VDC I would think that is the appropriate thing for all DC voltages. At least 48VDC and below.
When we build "backboards" for our telephone and signaling circuits we use fire rated plywood painted with fire retardant paint. The we mount all of our busbars, blocks, etc. onto that backboard.
Funny thing is we have to leave the square patch that shows the fire rating of the board unpainted for the inspector to see it.
Since all of our "stuff" is DC voltage. Mostly 48VDC I would think that is the appropriate thing for all DC voltages. At least 48VDC and below.
Yes the wiring has balance issues. Looking at the left picture you have both the main power connections at one end of the stack. Really should move one of the connections to the other end. Still not perfect but much improved.
The wood backboard is not the problem here, it's the use of an AC ground bus bar for DC power connections. Depending on his batteries and load he could easily push 200 amps. Most inverter specs do call for non-flammable mounting surface for their unit, which is not needed for daily operating temps, however if there is an electrical failure you have another layer of safety.
Maast
Compulsive Tinkerer
Regarding your original question: I've been operating on the idea that it'd only take one "oh shit" water leak to turn my non-conductive wood into a conductor. A pipe breaks and sprays water everywhere, roof leaks and makes a puddle right where the batt pack is sitting, etc, etc, etc.
I know for a fact pressure treated wood will get conductive when it gets wet 'cause I've been zapped by a welder while kneeling on a soggy PT board. I simply assume all wet non-treated wood will become conductive because who knows what species it is, what minerals are dissolved in the wood fibers, or what chemicals it may have been treated with..
I know for a fact pressure treated wood will get conductive when it gets wet 'cause I've been zapped by a welder while kneeling on a soggy PT board. I simply assume all wet non-treated wood will become conductive because who knows what species it is, what minerals are dissolved in the wood fibers, or what chemicals it may have been treated with..
I mount any heat generating equipment on Lynn superwool fireproof sheet on top of plywood. The Lynn stuff only adds 1/8 inch and good to 2100F.
For using AC bus bars for DC just use one of the calculators online to compute the current capacity yourself. Make sure to factor in the material and the true minimum cross section if it's Swiss-cheesed full of wire holes.
A rough rule of thumb is for each 1mm^2 of copper you can carry 1.2A. For aluminum that is 0.7A.
If going cheap a piece of copper water pipe that you flatten in a vice/hammer/etc makes great bus bars for dirt cheap.
For using AC bus bars for DC just use one of the calculators online to compute the current capacity yourself. Make sure to factor in the material and the true minimum cross section if it's Swiss-cheesed full of wire holes.
A rough rule of thumb is for each 1mm^2 of copper you can carry 1.2A. For aluminum that is 0.7A.
If going cheap a piece of copper water pipe that you flatten in a vice/hammer/etc makes great bus bars for dirt cheap.
The Hardyboard is really the best way to go!
Not for internal use. The silica dust it emits is a huge HSF issue as if breathed in you will have long term repository issues. For outdoor use it's fine as wind/etc blows any dusting away. For cutting the use of a proper respirator is important.
Of course, it's in the shed. After the pieces were cut then sealed with Kilz primer we were good to go, works excellent. I will also use the 1/4 Hardie board for the bottom, back and top of my battery bank.
Hmm , try that PVC. / Plastic / composite wood . It worked good for me , using bus / ground bars . This is my interior power / mechanical closet.
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teotwawki.je
New Member
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Mounting bus bars on wood & making battery boxes out of wood are 2 separate things.
I've mounted bus bars directly onto wooden electrical panel board (flame retardant) and added a "flying bridge" over the top so that if a metal spade fell onto it, there would be no contact with the bus bars. This seems to be to be perfectly fine (as long as the wood doesn't get wet/damp/mouldy). But this wood panel is a chip-board so quite brittle & not that strong so you would need to ensure that heavy cables are not pulling on bolts that might tear the wood. If the wood broke then there's a danger the bus bars could touch each other or anything else.
In the case of battery boxes, I'd first ensure mechanical strength, then consider coating with a flame-retardant if you feel the need. And certainly put a cover over it so that it is safe from dropped things. Probably some Kapton tape over each contact too.
I've mounted bus bars directly onto wooden electrical panel board (flame retardant) and added a "flying bridge" over the top so that if a metal spade fell onto it, there would be no contact with the bus bars. This seems to be to be perfectly fine (as long as the wood doesn't get wet/damp/mouldy). But this wood panel is a chip-board so quite brittle & not that strong so you would need to ensure that heavy cables are not pulling on bolts that might tear the wood. If the wood broke then there's a danger the bus bars could touch each other or anything else.
In the case of battery boxes, I'd first ensure mechanical strength, then consider coating with a flame-retardant if you feel the need. And certainly put a cover over it so that it is safe from dropped things. Probably some Kapton tape over each contact too.
I'm in the middle of my first build and just picked up a bunch of scrap steel stock from my local scrapyard for 25 cents/lb. Enough steel to do the whole rack for a battery bank that is close in physical size to what you've got cost me ~35$. On my way out, I also noticed that my yard sells copper and aluminum by the pound, and some yards will buy and sell bus bars (I called and found mine does stock them), so if you're on a budget . . . The cost of copper right now for me would be $5/pound, which is pretty good for electrical grade copper bus. The way you would size this is to make sure that the cross-sectional area of whatever bar you find matches the cross-sectional area for your required conductor, using an AWG chart for reference. The key is having sufficient cross-sectional area in your bar for the amps you will draw from the battery.
In terms of insulating materials, I also noticed that the scrap yard has old electrical panels with the insulating fiber glass sheets behind the bus bars. The material is something like this: https://www.mcmaster.com/8549K44/ I'm planning another trip soon to harvest these things. Scrap yards differ by location - some let you wander about, some do not. Still, if you can find what you need there or at the dump, you'll be doing your wallet a favour.
Another idea I've had for insulating the bus bar is to use a ceramic tile - you can get a sample at your local big box store, drill some holes (with the appropriate bit), and mount using rubber washers so as not to crack the tile. Not yet sure exactly what I'm going with, but am playing with that option, too.
In terms of insulating materials, I also noticed that the scrap yard has old electrical panels with the insulating fiber glass sheets behind the bus bars. The material is something like this: https://www.mcmaster.com/8549K44/ I'm planning another trip soon to harvest these things. Scrap yards differ by location - some let you wander about, some do not. Still, if you can find what you need there or at the dump, you'll be doing your wallet a favour.
Another idea I've had for insulating the bus bar is to use a ceramic tile - you can get a sample at your local big box store, drill some holes (with the appropriate bit), and mount using rubber washers so as not to crack the tile. Not yet sure exactly what I'm going with, but am playing with that option, too.
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Hardie board is not intended for structural uses. It will not support heavy objects where there is vibration — the screws will fail. I suppose it could be used as an intermediate, non-flammable layer with plywood below, but it wouldn’t be the best for that purpose because it does transmit significant heat.
Another option is FRP (Fiber Reinforced Plastic). I used a sheet of that on the bathroom ceiling in my RV. The standard FRP purchased at Home Depot is considered general purpose and is NOT fire retardant. However, there is a version of that brand that is fire retardant. I don't see it on the HD website unfortunately.
Menards carries the Nudo brand of FRP that has a Class A fire rating.
I bring up FRP because it's very easy to work with.
Menards carries the Nudo brand of FRP that has a Class A fire rating.
I bring up FRP because it's very easy to work with.
I really think the danger here is that wood is combustible NOT that wood is conductive. Take a look at Lichtenberg wood-burning on you tube and you get an idea of how hard it is get wet (with minerals in the water) wood to conduct. It is far from easy. I would look at some of the fire retardant paints on Amazon and call it a day.
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