Solar Electric Project

[hayden]

Since you guys have so many good ideas, any thoughts on how to best pull a additional wire through the conduit? I need to add an additional safety ground. I pulled a string through in anticipation of this, but managed to drop it down the conduit. I'm also worried about it being wrapped all around the existing wires and binding up when I pull the extra ground.

Maybe I can blow it out with a shop vac?

 

[charlz]

Just pull the string out, tie a baggy on the end and suck it back through with the shop vac. Be careful though the string can go screaming through there so either don't touch the string or wear gloves or both. Once you see how effective this is you won't touch a fishtape for conduit pulls again

 

[Defective]

So many good ideas. As soon as I get good at this, I'll be done with my life-time quota on conduit wire pulls.

Easy solution: Get a job with an industrial electrician. If you end up wiring airports and you're low man on the totem pole you get to empty the mice & gophers out of the shopvac at the end of the day...

Just pull the string out, tie a baggy on the end and suck it back through with the shop vac. Be careful though the string can go screaming through there so either don't touch the string or wear gloves or both. Once you see how effective this is you won't touch a fishtape for conduit pulls again

Bad news...You'll probably have to play with the string as it'll be twisted around the existing wires. I'd try pulling a light rope through first.

The only two times I recall a wire missing when I did this stuff as a kid, (Oh man...I feel old...I was in my twentys at the time...) we ended up pulling the wires back out & starting over.

 

[SPIKER]

seems like once you get the wires in they powers that be change their minds on me dang it anyhow.

one question you have std 2x4 conduit support are you planning on replacing that one with something better i hope?

mark

 

[woodlandfarms]

Once wires are in the conduit and you've lost your string you are a bit boned. You can try the shop vac and see if it will pull the string up (I have seen it tried, never seen it work). You can try and pull a new string with baggy at the end with the shop vac (seen it work twice, but both times in a big pipe with heavy cable laying at the bottom) Or you can pull one of your wires out with a two strings attached. One string will pull back the old wire with the new wire, and the other string is left for future work.

It is really important to use lube (there is special stuff at HD that works good, although I know a lot of guys who just use dish washing soap). Also, important on these later pulls to make sure your string is strong (overkill can be good) and that you use the best methods you have available to connect the string to the wire...

I pulled miles of AV wire for a friend of mine who was putting in 67 TV sets in this billionaires home. Just to make you cry, this was 7 years ago, and the guy spent 40 mil on the house, and 40 mil on restoration... another 100 mil on art. All in cash. We figured his monthly nut to operate the house was around 150K.... We asked him and he said that he put some money in the bank and the interest he was earning was enough to cover the nut...

 

[hayden]

seems like once you get the wires in they powers that be change their minds on me dang it anyhow.

one question you have std 2x4 conduit support are you planning on replacing that one with something better i hope?

mark

Are you refering to the 2x4's that are holding the conduit to the poles? Yes, those will go away and I'll secure the boxes to the poles some better way - haven't figured out exactly how yet - need to visit the supply store to see what's available.

 

[hayden]

Thanks for the suggestions. The string is still accessible at one end of the conduit so unless it's totally wrapped around the wires I should be able to get it out.

Now that I have something through the conduit repulling the wires wouldn't be the end of the world, mostly because I could pull them down hill.

I think I'll try to remove the old string first, then try to blow a new string/rope through to pull the new wire. If that doesn't work then I'll pull them out and do it again.

 

[mjncad]

Darn! Where were you yesterday?

Drinking beer!

All of you guys suggest using a Shop-Vac to suck the string and/or baggie through the conduit; what size Shop-Vac are you using, and on how big of conduit, and for how long?

I recall when I was at NREL, we were working with the IT department on stringing lots of fiber optics cable on campus, and one of the methods to be used involved a light weight umbrella (baggie) in the pipe attached to a string and compressed air to blow the pull-rope down the pipe. At the head end was a special plug attachment that allowed the pull-rope to slide through the plug with minimal air loss. The plug also had a connection for the compressed air hose. I seem to recall they were using a trailer mounted compressor as some of the conduit was 4" - 5" in size.

 

[Defective]

Last time I used the shop vac trick, I was pulling through 300' sections of 2", 4" & 6" conduit. Some was rigid pipe & some was poly flex. It was pretty much a standard shop vac. (Commercial model, but nothing special) We pulled string through with a big lump of rag soaked in Yellow-77. Then we hand pulled a 1/4" rope with the string. Most of the runs (totaling around 4 miles of conduit) we then hand pulled either 2 #2 sheilded or 6 #8 wired. There were a couple we used the truck for, but you'd be surprised what you can do with a strong back & about a thousand gallons of Yellow-77...

I've never liked the compressed air method. It's a pain in the butt when things get tangled (& they will...). With the vacuum method, you can often just suck the tangled line through.

 

[SPIKER]

I have used a WOOD SHOP DUST COLLECTOR that I bought from harbor freight 3 or 4 times now. it works quite nice it cost like 79 bucks years ago and is still available for similar price on-sale... I pulled 200 amp "U.S.E." cable through 4" corrugated pipe under ground several times. even added one string to my primary run to the pole barn after the 2#2 and 1#3 al cable was in there this way used a plastic wallymart type bag tied to the string (kite type string only heavier and also used bailing twine the good poly type not the older hemp type) then pulled in the rope and used rope to pull wire. also I did this for a living for 5+ years working with a guy who is now building the nat gas pipe line across canada to anchorage prudo bay project. he is setting & building the stations. we once pulled about 14 miles of wire into 3" conduit run that was some where about 400' long when we rebuilt one of the factory's Kilns & brought it up to NEW spec. only engineer messed up and we had 2 times wire we actually needed.. his response was oh well we can call those 150 wires all spares!

Mark