annodes

[Boomer gone soft]

How deep do you guys bury your sacrificial annodes when you install them?

We rarely use them, but had to install one today. One guy thought we needed to bury it the same depth as the ground rod. I handed him my shovel, then he changed his mind.

[pre_apprentice_ID]

[QUOTE=boomer..
I handed him my shovel, then he changed his mind.[/QUOTE]

Haha! Great idea until he had to shovel!

[Boomer gone soft]

heh, heh, heh...
What a GREAT job you got man! 37 years old. God Love ya.:cool:
http://en.wikipedia.org/wiki/Galvanic_anode

soooooooo........

In other words, you don't know.

Your link didn't say. Danny's boy probably deleted it......

btw, I'm 38 now. Happy birthday to me, asshole.:rolleyes:

[thrasher]

You didn't say what the anode was protecting, old bare concentric neutral cable, anchor near a railroad or pipeline, etc. When we were putting in anodes to protect old style bare concentric neutral cable we used a 5 foot galvomag with the bottom of the hole 10 foot deep. The Coop was doing so many of them we bought a small augur (about 12") for one of the oldest digger trucks and installed the anodes with the digger truck. Then used a trenching shovel to connect back to the line at a trans or cabinent. If we needed a full size bed then we brought the little trencher to tie everything together. To protect anchors we used a little short anode and just put the top about 18 inches deep but between the railrod and the anchor.

[Boomer gone soft]

You didn't say what the anode was protecting, old bare concentric neutral cable, anchor near a railroad or pipeline, etc. When we were putting in anodes to protect old style bare concentric neutral cable we used a 5 foot galvomag with the bottom of the hole 10 foot deep. The Coop was doing so many of them we bought a small augur (about 12") for one of the oldest digger trucks and installed the anodes with the digger truck. Then used a trenching shovel to connect back to the line at a trans or cabinent. If we needed a full size bed then we brought the little trencher to tie everything together. To protect anchors we used a little short anode and just put the top about 18 inches deep but between the railrod and the anchor.

We just had about a 1/2 mile of 3 phase cable bored in along a roadway immediately adjacent to a lake. In the middle there is a j box because our specs require a cable to be grounded every 1/4 mile (and the cable needed a splice). There are no elbows only splices and a ground rod in the j box; it is a 6' x 6' flush mount box on the shoulder of the road. The cable is standard jacketed 4/0. About 1' from the splices, we installed grounds on the cable. I had never used them before; 2" of jacket is removed and a kit bonds the #6 cu ground to the concentric and seals the jacket. All 3 grounds are then bonded to the ground rod. I am assuming the engineer is trying to protect the ground rod; the annode is bonded to the ground rod.

Like I said, I have never seen an annode used in this way and was just curious what you guys think; and more specifically if you think the annode needs to be at the same depth as the ground rod.

[thrasher]

In your application I would think the center of the annode should be roughly the same depth as the center of the rod and I would seperate the two by the length of the rod; but this is just a rule of thumb based on previous work around railroad beds. To be perfectly honest unless the cable is running through very different soils I wouldn't expect there to be that big a problem with corrosion of the ground rod. Normally you get max corrosion from one of the following (1) cable run thru soils of very different composition with water and oxygen available, (2) heavily fertilized fields, (3) exposure to DC signalling systems, (4) exposure to pipeline anode beds, or (5) exposure to large beds of emplaced metals especially if they are electrically connected back to the system neutral.

[Boomer gone soft]

In your application I would think the center of the annode should be roughly the same depth as the center of the rod and I would seperate the two by the length of the rod; but this is just a rule of thumb based on previous work around railroad beds. To be perfectly honest unless the cable is running through very different soils I wouldn't expect there to be that big a problem with corrosion of the ground rod. Normally you get max corrosion from one of the following (1) cable run thru soils of very different composition with water and oxygen available, (2) heavily fertilized fields, (3) exposure to DC signalling systems, (4) exposure to pipeline anode beds, or (5) exposure to large beds of emplaced metals especially if they are electrically connected back to the system neutral.

I didn't really see the need for one either, but then again......I'm not the engineer. The soil is sedimentary typical swamp shit and it is quite wet.....perhaps that was his reasoning.

Thanks for the discussion. It's nice to have a civil discourse about something....:D

[thrasher]

Thanks for the discussion. It's nice to have a civil discourse about something....

I agree. BTW do you guys use annodes routinely or was this a one-of-a-kind job?

[duckhunter]

Is that the reason for the annodes? We do not install them here. We have never had neutrals disappear like other utilities across the country. I remember when we went to jacketed cable, we wondered why were doing it. The old concentric created a better grounding system in those areas. As we replace old conductor we are forced to ground differently to achieve the same results.

[Boomer gone soft]

Duck, all of our concentric is jacketed. I have seen concentric corrode away at other utilities but only on unjacketed. Are you saying your jacketed concentric disappears? Like I said, I assumed engineering was trying to protect the ground rod.....but all of it is bonded together.

This is the first time I have seen our engineering use an annode (other than on gas installations), but this is also the longest continuous run of cable we have installed....and it was installed in very swampy soil (perhaps high pH?)99% of our installations are still OH.

[duckhunter]

All of our UG is jacketed now and has been for several years. All the co-ops had to go to jacketed concentric several years ago because some places across this great land the concentrics were disappearing. We nevr had that problem. But because years ago we borrowed RUS money we had to follow their standards. When we went to jacketed concentric we were forced to drive multiple rods to reach a desired Ohm reading.

When I worked in the oil field here in Michigan we had sacrificial annodes.

[thrasher]

My first job in the industry from 78 to 91 was in Northern Virginia where there are tremendous variations in the soil. Across one good sized UG subdivision you could be in red clay, blue clay, solid stone (so you lined the ditch with sand), alluvial deposits and everything else. The Coop had first started burying bare concentric primary in the mid 60's and there were lots of places where the neutral was disappearing, or if still there was severly pitted and very brittle.I remember one section where it got so bad we couldn't reliably "thump" cable because there wasn't enough neutral for a return path. So starting about 81 anodes were retrofitted to hundreds of sites to try to protect the old cable. And soon after we went to jacketed cable for all new work.
The Coop I'm at now (Southeast Virginia) has very uniform soil (even if very wet) and the places we have dug up cable for one reason or another the neutral has been in good shape. This Coop also went to jacketed cable in the mid 80's so we do only a rare annode.

[climbsomemore]

Buried a few zinc bars cast in plaster as anodes... to keep the lead on lead sheathed cable.

In that system... the neutral (a seperate copper wire in the duct bank) would be grounded to a low impedence copper ground rod (spec to 10-25 ohms or less than 10 if we could get it). The sacrificial zinc was bonded to the lead sheath of the cable... and that got buried outside the vault- opposite of the end we drove the ground rod at.

When you do sacrificial anodes... you have to isolate the lead from the grounded cabinets or whatever equipment it terminates in. Old paper and lead potheads bolt with a flange... we had to add a isolator between the flange and the grounded cabinets, and slip bushing around the bolts to break their contact to the grounded metal too. Or we could cut a ring out the the lead sheath to break it's continuty to the ground.

If the annode was not isolated from the grounded neutral ... circulating current would eat up the lead and defeat the annode... the annode is supposed to sacrifice it's free electrons easier than the lead (or gas line or copper neutral or ships hull --- this idea is used in many applications) so the protected object lasts longer.

[climbsomemore]

just a thought... does your gas company in the area use an anode corrosion protection to it's pipeline?
Sometimes that is the cause of the circulating current that's eating your bare neutral up... and that effect can be worsened by soil conditions.

Consumers over in Michigan has to put johnny balls in its ungrounded guy wires... when they grounded the guys years ago.. that current would eat the galvizing (zinc) off the anchors and guys and they would rust and fail.

They have a lot of ate up old buried neutrals too.... but I dont think the UG engineer ever made the connection (pun) to the cause.

The same company (consumers) has gas in most of it's electric area... and the gas lines have cathodic anodes.