Ground Mount Brace Opinions ?

[Syberdog]

Well for better or worse I brushed the in-conc portion with a coat of roof adhesive asphalt up to a taped line... now they will just rot off at the bottom of the block.
Will check out Alodine to see if that will be in my budget, otherwise paint is fine or maybe even clear coat would work.

I have both regular anti-seize and copper based - would the copper work just as well for this application as the nickle based?

[kb58]

Alodine's pretty affordable considering, http://www.aircraftspruce.com/catalo...clickkey=11999

Brush on, wait a few minutes, and hose off.

[kb58]

I don't have a problem with stripping bolts, but I keep forgetting that most haven't had 7 decades of
experience to get their wrench arm accurately calibrated. I have doubts about lock washers. What
alloy are they made of, is it compatible with exposure and the other metals? If the materials in the
stack up held together by a bolt can move at all under stress or shrink slightly, the lock washer will
loose its tension. Putting a second nut against the first will never come loose, even if its rattling
around in the hole. This can be a problem with electrical connections involving insulation in the
stackup.

Extra nuts also protect any exposed threads: I'm the only guy I know that can reuse
muffler clamps several times. Bruce Roe

You can always use Nyloc-nuts

[Edit] Though since the rails and frames are usually intended to be electrically grounded through the hardware, you're stuck with internal or external lock washers because they dig into the material and ensure a good electrical connection.

[J.P.M.]

Thanks for reminding me JPM, I planed on using anti-seize (learned a long time ago the hard way). I don't know if it will do any good but in addition to the flat & lock washers, I have a external-star washer for the head side, to help with the bonding issues. I thought the Torque recommendations found in the various OEM install manuals tended to look pretty low for 3/8" & 1/2" (20 & 30 Ft.Lbs) but if that's all it takes..... thread locker or another nut might be a good idea.

So kb58 are you suggesting paint or ??? the exposed alum.?
hmmm... flake purple or green spiderweb....

I did a lot of pressure vessel design back in the day. Bolted flange design for vessel nozzles and closures, and also piping was usually a very important subset of that. If stainless bolting was specified by the design, I'd usually try to avoid the need for KY type antiseize lubes, etc. and use 400 series martensitic stainless for the bolting if I could. That usually avoided the galling issue, and was often less expensive than 300 series austenitic studs and aluminum bronze nuts to avoid galling, particularly for higher pressure applications where the lower allowable design stress of the nuts made the design a PITA or unworkable. FWIW, the antiseize lubes, if used had to be renewed if the flange was ever opened, and they tended to catch dirt more easily than a dry set of threads. It was a crap shoot if a maint. person would take the time to do the possible/likely extra cleaning necessary to a stud before running the nut up and causing problems from the extra dirt. Things my mother never told me. I never had a lot of faith in being able to avoid galling with antiseize lubes anyway, so I designed around them as much as possible, whenever possible. They seemed more of ointment on a wound than avoiding the wound occurrence by design.

[bcroe]

You can always use Nyloc-nuts

[Edit] Though since the rails and frames are usually intended to be electrically grounded through the hardware, you're stuck with internal or external lock washers because they dig into the material and ensure a good electrical connection.

There might be a conduction guaranteed "washer" in the mounting, but it doesn't depend on
spring tension to work, and isn't directly exposed. These may still be a bit of a liability, but they
are only required on a few of the total joints.

I don't use elastic nuts on a solar array because 1. I don't know how well the nylon will hold up
over years of exposure; and 2. They don't cover the extra threads. Bruce Roe

[Mike90250]

Before you pour, you have to put some rebar or mesh in those holes. Big chunks of concrete without rebar, become little chunks in a short time.
Hardware should be SS steel nuts, bolts and washers, and I simply use the same tube of no-ox for connections, as anti-size in the threads and it works fine. Adding another metal like copper or zinc, is sketchy.

[Syberdog]

I admit, I've made choices based on one criteria and not another, made a few oversights and mistakes and avoided a few "down the road" problems, because of your advice. I want to thank all of you, especially J PM, bcroe and kb58, for your helpful information and discourse. You really have made a positive difference in my project.

I have thought some more on NEOHs suggestion of bracing the Mid-table span instead of the cantilever. It seems to be the better choice between vibration dampening at the top end or supporting the longer flex area. Ideally I may do both.
To support the upper end I end up with an long and awkward angle
To support the middle span, I have to cut the 2"x 5" angle and will end up with about 1.5' scrap.
If I jiggle it a bit, I might be able to use the drop to short-brace the upper portion.

Here is another mockup to get an idea of what it would look like...




Also thanks to Mike 90250 for pointing out the ground rod in another thread- I guess I was assuming I could make a ground rod the old way from back up in the hills... I found copper coated ground rods at the bigbox -now to pound in all 8' or find out if burying in/thru conc. is allowed. I also had planned on a couple sticks of rebar in the bottom of the ballast but after additional consideration I have added a 6' WWF in the top and around each I have 4 #3.


I still have questions on the Anti-Seize, No-Ox-ID, Bonderite subjects..., should I continue this thread or start new ones for each question?
Thanks for your help guys
sd

[foo1bar]

-now to pound in all 8'

The pictures make me think it's a rural area where you probably have a fence-post driver already.
If the soil isn't too bad you can get a rod pounded in pretty quick with a driver - and the last few feet don't take too long with a small sledge. (really depends on the soil of course)

or find out if burying in/thru conc. is allowed.

You could do a ground rod that basically is entirely in your concrete - Search "Concrete Encased Electrode requirements".
Just an 8' ground rod wouldn't qualify as one..
Nor would wire mesh like you have.
Maybe you could do 20' of copper wire (#4) - looks like you have enough space that basically around the entire perimiter ~6" in from the edge would get you to >20'
Or my understanding is 20' of 1/2" (#4) rebar, tied together with metal tie wire.

[Mike90250]

Concrete encased conductor requires minimum 20 feet length of un-spliced half inch rebar. 6 inches can protrude above the concrete as the connection. Other metal (rebar, mesh) must be electrically bonded to the initial 20' rebar. I don't remember the minimum size of slab foundation that is required, something like 900 sf of slab full of interconnected metal,

[DanS26]

A simple and less exhausting method to sink a ground rod is to dig a small depression in the ground and fill with water. Then take the rod and using piston action, move the rod into the ground. Add water as necessary to keep the hole lubrcated. If you hit a rock, remove rod and move over six inches.

With this method you can sink a rod in less time than you can get the stepladder and sledge out of the shed.

[sensij]

A simple and less exhausting method to sink a ground rod is to dig a small depression in the ground and fill with water. Then take the rod and using piston action, move the rod into the ground. Add water as necessary to keep the hole lubrcated. If you hit a rock, remove rod and move over six inches.

With this method you can sink a rod in less time than you can get the stepladder and sledge out of the shed.

+1 on this method. I've quickly sunk a few rods in soil with clay layers that require a pick axe to dig through, would have been there all day if I tried to just brute force it with a sledgehammer.

[Syberdog]

heh...heh... The entire trench, ballast block hols and post holes had to be dug that way- 6" at a time. When my ground is dry, they call it calichie!
Fortunately NO rocks in the soil but... it just so happened the site I picked had 2" of old gravel driveway along the full length.... All Dug by hand... in 90 degree heat... uphill both ways !

[tyab]

If you want a description of the compliant ground electrodes, take a look at 250.52 and 250.53 on the installation requirements.

[Syberdog]

If you want a description of the compliant ground electrodes, take a look at 250.52 and 250.53 on the installation requirements.

Where would I find that information? (the "installation requirements).

[foo1bar]

Concrete encased conductor requires minimum 20 feet length of un-spliced half inch rebar.

Unless there's additional requirements from the local AHJ it can be multiple pieces tied together with steel tie wire.

NEC 250.52(A)(3)(1)
"installed in one continuous 6.0m (20 ft) length or if in multiple pieces connected together by the usual steel tie wires exothermic welding, welding or other effective means to create a 6.0 m or greater length."

Other metal (rebar, mesh) must be electrically bonded to the initial 20' rebar.

What is the code citation for that?
I'ld say it's a good idea, and I'd even say it really should be done.
But I don't think it "must" be done since I don't know of any code requirement. (But please correct me with the section of code that says that)

Since the OP has some nasty soil conditions, if it were me I'd grab some 4AWG bare copper and do a CEE. (20' in the slab and whatever is needed above ground to get it to where it's to be connected... Looks like at HD it'd be $46 for 50' of 4AWG. Probably can get cheaper than that at an electrical distributor house.