| Author | Message | ||
| nvnenzel (65.54.97.198)
Rating: N/A |
I want to start by saying ARRRGGGG ( I think I spelled that right.) While installing a sprinkler system it dawned on me that while I had the trencher this would be a great time to run a trench and install an electical service for the rolling house at the RV pad. Not gonna lie, bus nut sans bus, but someday. I've found over the years this is the place to be for advice, thanks Ian and all of you who write to the board. Anyway, while at the mega-go-low-home-jimmy-johnson-shops-here-mart I inquired to the very aware 17 something year old that I wanted to run wires for a 50 amp plug for the rolling house. I figured 50 amps since eventually when I grow up and join the big bus crowd I could wire the coach for 50 amp. After all, I figured it was better to over build than to under build. "That's a 115 service, right?" he asked. I know my 30 amp was 115 and that I could plug into a 50 amp with an adaptor no problem, so I assumed that yes, it was a 50 amp 115 service. "No problem," said the wanna be mr. Johnson, "just run three 6 gage wires, white, black and green through conduit to the fuse box and buy this 50 amp. RV panel." I know the fuse box can handle the load, the previous owner of the house ran a furniture business and had several large 230v saws, planers etc and the shop is rated for small industry. What the heck I thought, so I bought the 50 feet of white black and green wire, ran it through conduit buried the required depth according to the local codes web site and got ready to call the professional to hook up the whole darn thing, but a funny thing happened on the way to the forum. I noticed the the diagram in the plug (RV box) said I needed two lines, one ground and one common, or four wires, to make the thing work. I guess my question is, am I up Jarbidge Creek without a paddle. (you would have to be from far rural Nevada to understand that reference.)Is the 50 amp service available in most new RV parks really a 230V? Do I need to run a fourth wire? Can I run a 30amp if this doesn't work? I'm asking so I don't have to explain to the professional electrition that I took advice from from a kid, buried the lines and... well, I just wanna look like I know SOMETHING, which of corse I don't. Thanks in advace for your answers. | ||
| John that newguy (199.232.244.27) Rating: N/A |
There's a wealth of information here: http://users3.ev1.net/~crossstitch/ | ||
| harold mckeown (152.163.252.199)
Rating: N/A |
You do need the 4th wire, it can be a bare copper ground wire buried beside the conduict if the conduict is too full to add another wire.Yes it is 220 volt and yes you can use what you have for a 30 amp. plug | ||
| Jerry Liebler (165.121.36.5)
Rating: N/A |
Just get a red # 6 of the same length, pull out the three with a rope tied to them, then pull the 4 in. This is even to code if your conduit is 1& 1/4" or larger. But if you've got 1" it'll fit but it is over the code allowable fill. Since the code only allows 270 degrees of bend it'll pull just use lots of lubricant. Yes the 50 amp rv service is 240/120 and needs 4 wires. And yes you could run a 30 amp with out changing the wires. I recently pulled 3 ea 1/0 and 1 #2 thru 200 feet of 1&1/2 " conduit with 3 90 degree bends. It took 3 young guys pulling and 1 old fart lubing and pushing. Regards Jerry 4107 1120 | ||
| Darryl (68.184.123.198) Rating: N/A |
Harold is right on all accounts. If possible, you might consider trying to pull a new wire through it with the old one though. This could work if there is enough room in the conduit. | ||
| John that newguy (199.232.244.27) Rating: N/A |
If you run that fourth wire and do this job yourself, make sure you also pound a 5' ground rod (or two) at that far end and bond it to the ground of that outlet box and that ground wire. You'll want to insure that there's a balance of all common grounds. You'll want to do that anyway, even with a 110v 30amp service. The 50amp service is 220v; 110 per leg, neutral and ground = 4 wire. | ||
| TWO DOGS (65.179.201.194) Rating: N/A |
the conduit can be the ground | ||
| nvnenzel (65.54.98.166)
Rating: N/A |
Thank you, thank you, thank you and darn! It didn't dawn on me to check with the busnuts first. I'm gonna go back since the ground is still soft and re-dig the ditch, lay a solid copper, ala what harold said and then call the pros. The conduit is 3/4 pvc and I had a heck of a time pulling the three, I don't think four will go, ain't gonna try, but thanks for the thought Jerry. I'll pound the ground rod as well, but John, do you mean at the RV end? Not at the fuse box I would assume. A note the to world. I could have gone to the pro's and saved a lot of time, but I went to the big box shops. There's nothing wrong with the Home Depot's or Lowe's, but you had better know what you are doing BEFORE you go in. | ||
| Phil Dumpster (24.16.243.37) Rating: N/A |
You would have been much farther ahead of the game if instead of using conduit and single conductors, to just buy direct burial cable. Type UF, has a sheath that is impervious to lots of things (except heat). Looks like Romex but usually a dark grey instead of white or black. For a 50 amp service, the 6 gage four conductor cable has green, white, black and red conductors. The red conductor is used for the second leg, the black for the first, the white is the neutral and the green is ground. Some UF cable has a bare ground conductor instead. I've used it on a number of projects and it works well and is so easy to work with. Hammering in a ground spike wouldn't hurt but I wouldn't bother with it. | ||
| Tom Connolly (Tomconnolly) (64.58.196.218)
Rating: N/A |
First the service is 50a / 220v, the preferred wire size with copper is 2@ #6 THHN (black), 1@ #6 THHN (white) and 1@ #8 (green). Although 8/8/8/10 THHN is code for a short run @65a. I would personally use 6/6/6/8 for 50 – 150 feet Second it is against the NEC to add a ground rod at a remote point in the circuit, it causes a difference of potential hazard. There is however one exception where a 2nd ground rod can be used to reestablish a ground and this is not it. If you want to increase your ground you can add additional rods at the main service entrance space them a few feet apart and bond them to the same point. Also the ground and neutral are kept separate at the RV panel and bonded at the service panel. Tom C | ||
| John that newguy (199.232.244.219) Rating: N/A |
Since us old phone guys never did "NEC" stuff, we just did what we were taught; We bonded our ground circuits to the electrical ground and always put a ground rod at the far end of a run and bonded it all together. While NEC "rules" would declare that it is absolutely necessary to have errant energy travel back to the fuse panel via that ground lead to insure tripping the breaker/fuse, lightning follows no such rules. Adding a breaker to the RV socket at the far end and using separate ground rods, all bonded to the rest of the system, is by far the better choice. "NEC" or no "NEC". http://www.electrician.com/electa1/bond.html | ||
| John that newguy (199.232.244.219) Rating: N/A |
Of NEC interest: http://www.imsasafety.org/journal/janfeb/article1.htm Please notice the word "required". | ||
| Just an opinion (199.64.0.252) Rating: N/A |
Well, maybe it's just me, but I don't think what Harold said is the best way to go... You've already run black, white and green through the conduit. Correct? So you already have your ground wire in there (the green one). You can't change the color. Green is for ground. You can't run a hot leg on a green wire. It could get someone critically killed. I don't believe there are any exceptions to this. You need another hot wire, and you can't just run it alongside the conduit. You should either pull up the 3/4 conduit and replace it with 1 1/2" conduit, and add a red wire to the other three, or you should remove the three wires completely, run 3 conductor with ground UL direct burial along side, and then use the 3/4" conduit for running phone and cable wire out to the power post. just my opinion. | ||
| John that newguy (199.232.244.219) Rating: N/A |
Damn good opinion. If one's going to worry about "code", they oughta' worry about "color code" as well. | ||
| Jim Ashworth (Jimnh) (172.169.27.139)
Rating: N/A |
Easiest thing to do now is to replace the wires with four 10 gauge and run a two pole 30 amp breaker. This will at least give you some 240 volt and enough to run 2 a/c's and more if you want. Four #10 wires would be a piece of cake to pull thru the 3/4" conduit. OR try to get four #8's in there (that's max for the conduit so it might be a little tough) and run a 40 amp breaker. Either way you'll have plenty of electricity. Jim | ||
| Tom Connolly (Tomconnolly) (64.58.196.218)
Rating: N/A |
You can change the color of the existing wires by using color code tape or heat shrink. Simply tape or heat shrink the correct identification colors on the last 6 inches of each end of the wires. (both are available at the local home center)All the wires need to be in the same conduit. Having lived in the lightning capital of the world since 1967 and having spent all but the past 3 years here as an electronics repair technician, I strongly recommend against reestablishing a earth ground for a residential application. Additional ground rods at separate circuit locations are the #1 cause for lightning damaged electronics, and as stated earlier it creates a difference of potential hazard, and is against NEC code. An especially bad idea in dry or sandy soils where the electrodes are not deep enough to be in the moist soil 100% of the time. The 4th wire is for safety; the circuit will have 2 wires at the same potential the green ground and the white neutral wires are bonded at the service panel. This is the method approved for the RV panel and sub-panels. I’m done, now go do it your way. Tom | ||
| John that newguy (199.232.244.219) Rating: N/A |
Tom... Being "not required" and being "against" existing NEC rules are two very different things. I've been on enough lightning damage investigations to know the benefits of grounding/bonding the far end of remote locations. While the NEC may -not require- added ground rod(s), it is more than prudent to add one at the end of a long run to the remote location, especially if in a high lightning area. | ||
| Jerry Liebler (165.121.32.104)
Rating: N/A |
In most places there are permits and inspections to deal with in addition to the liability issues and insurance company's looking for an excuse to avoid paying. Few if any inspectors will allow a green conductor carrying current. The 3/4" conduit is only allowed to carry ONE # 6. The only way to rescue this mess is to replace the conduit with 1 & 1/4" or larger and add either a black or red # 6 to the 3 removed from the way overstuffed conduit. I doubt that you'll find an electrician willing to hook it up as is and hope there is no inspector that'll pass it and KNOW that no insurance company will ever pay a claim due to anything electrical when they find it. I hope you had a locate service find all burried stuff before digging, trenching thru a gas line could spoil your day. Happy digging Regards Jerry 4107 1120 | ||
| Cliff (Floridacracker) (65.33.16.84)
Rating: N/A |
You can put in all the ground rods you want as long as they are connected back to the ground at the main point of entry of your commercial power service. The danger comes when you don't run the ground wire and just drive a ground round at a remote location. Telco or Cable used to put in there own ground rods if they entered away from your power meter, now they can still do that but they must bond there ground to the power ground. The truth is the only real ground is usually at the closet pole or transformer to your house. The power company ohm's out there ground to protect them from stray voltage and lightning, the ground rod at most homes is a safety at best. Checking your ground at the power meter ground on a yearly basis is a good idea, you would not believe how many I find loose or non existant. Cliff | ||
| John that newguy (199.232.244.219) Rating: N/A |
Yup! - Called "ground bonding" among us old tele fools, Cliff. But the far end rod also serves as a "fail safe" ground. Should the ground ever fail between that house-end panel and the far-end fused outlit, the added ground rod will serve the need intended. I once inspected a phone booth lacking the ground rod at it's location at the edge of a parking lot. The power line's ground lead feeding the booth's lights went faulty at the power panel (inside the building), leaving the booth "hot". I found first-hand, that if you go to enough RV parks, you'll find more have deficient electrical hookups than those that have "safe" hookups. Many are "hot" due to reversed wiring someplace between the panel and remote locations. Code - schmode, I don't like to get fried. | ||
| Stan (68.150.152.113) Rating: N/A |
How do you determine the resistance to ground? I know that power companies usually have a counterpoise ground in the bottom of the cooling pond at the gererating station but how do you get a reference to that ground? Is there some way to figure the resistance of the power companies ground wire all the way back to the generator? | ||
| Cliff (Floridacracker) (65.33.16.84)
Rating: N/A |
They use a Megger. Heres a link to explain it better than I could. http://www.tpub.com/neets/book16/68f.htm | ||
| Stan (68.150.152.113) Rating: N/A |
Cliff: I know how to mesure resistance, but if you go to your service entrance, what do you use for a reference point for ground? How do you know that the power companies ground rod is at the same potential as the ground at the generating station? In fact, how does the power company keep all their ground rods in an area at the same resistance to ground? These questions have bugged me for years. When I was using sensitive electronic equipment, the neutral wire always showed a voltage to the ground wire and this created measurement errors. The inspection authority would not allow me to connect them together at the bench and their standard reply was that the voltage appearing on the neutral was not lethal. | ||
| Cliff (Floridacracker) (65.33.16.84)
Rating: N/A |
Stan, Here's the deal as I understand it. The Megger allows you to measure the resistance to ground by attaching one lead to the power ground wire and one to the ground rod being installed. The Power boys are looking for around 25 ohms or less. This is considered the same ground potential as at the generator. I'm sure their is some scientific rule or formula, but I don't know them. I have seen 10-15 8' ground rods driven to get this. Sometimes they never get it (sandy soil etc...) Here's my point, At your meter they only put 1 or 2 rods 10' apart, Their is no requirement to ohm them out so basically they are their as a safety backup. If the power ground is lost because of a loose or missing connection, tree took down the neutral, you still have some sort of ground. As long as your bonded to the power ground you can put as many as you like. I like the extra safety factor. And on voltage on the neutral, remember if you have an unbalanced load (L1/L2)the neutral is technically returning the unused portion back to source. | ||
| Stan (68.150.152.113) Rating: N/A |
Cliff: I kind of guessed that they used their ground wire as a reference even though it may be hundreds of miles from the generator. That piece of cable with all the splices and corrosion sure has low resistance! In the discussions I mentioned in the previous post the inspector told me that I was not measuring voltage to ground but that the voltage was on the ground. He explained how an inbalance in the system of a distribution transformer would cause ground currents to flow between the ground rods at different buildings. That really made me wonder how you measure the resistance on a ground rod that has a voltage on it. | ||
| nvnenzel (65.54.98.108)
Rating: N/A |
Once again, this goes to prove, Measure once, cut twice... or is it the other way around. I broke down and went to a "professional" electrical supply shop. After the techs finished laughing at what I'd done and from whom I had aquired my information they came away with this, considering what I had already done. Dig it all up, 1-1/2 conduit and 4ea. 6 gauge wires. Although I don't need an inspection to do what I'm doing one of the techs commented that if there was ever a problem related to the electrical and the inspector saw that bare copper wire running from the plug and or the box I would be the one suffering the shock. They also wondered why I hadn't done what Phil mentioned above, direct burial? I actually asked about this at the box store and the response was, they don't make direct burial that big. In the end and since I'm outta time, vacation is almost over, I'm going to mount the 30amp RV plug and if in the future I need to expand I'll run a trence a few feet from the existing ditch, wire a PROPER 50 amp service and just leave the 30 amp installed. I can't imagine any case where I would use both services at one time. Also, as Jerry mentioned, I did have the power company come out and mark the wires, etc. Since I'm on twelve acres, no gas, water well located on the other side of the property I almost blew off the utilities marking. Glad I did't. I had assumed the power for the garage came from the main box located on the house and the buried cable would be a straight line to the shop panel, WRONG! The wires went to another shed, turned a 90 degree and cut across the RV pad parking area only about three feet from the trench went for the RV power and completely on the other side I had assumed. I guess the previous owner figured he would eventually supply power to the shed and he could just dig down and tap into the main line in the future. Even though I would have missed the main supply, the thought I had no idea where the power was scared the tar out of me. Thanks again folks for the whole thing. Enjoy your summer. | ||
| H3Jim (68.107.62.94) Rating: N/A |
Coaches are getting cheaper by the month. What coach do you want to get? | ||
| Richard Bell (Richardkan) (152.163.252.199)
Rating: N/A |
One thing that you didn't tell us was the distance that you are running your new RV service. Our local big box store sells #6 THHN wire by the foot and I am assuming that is what they sold you. According to the 2004 NEC, you should be able to get 4 #6 THHN conductors legally into a 3/4" PVC conduit. That being said, if the run is of any length at all, you WILL find it very difficult to pull all four into the pvc conduit without the use of wire pulling lube. Also,the NEC also allows the installer to "change the color" of the cable by marking (usually by colored tape) the length of exposed cable. As for your grounding conductor, the NEC has a chart showing the minimum size grounding conductor required for a electrical feeder. (Table 250.122 for those of you with da book). It pretty much shows that for a 50 amp feeder, you would need #10 copper ground. This can be bare or green insulated. No matter what, you MUST have a ground wire in your pvc conduit run, no exceptions. So here would be my solution. Go back to the DIY and get one length of #10 copper, Bare or green, a roll of red marking tape and a quart jug of wire lube. Pull out the three you got in so far. Put the red tape on the green #6 that will be sticking out of the conduit and put all four wires back in. Do not skimp on the lube when you do. Voice of many experiences, especially on the lube part!  As far as the D-I-Y's go, just how much liability are they accepting by having any of their associates give out free electrical advice? |