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I’m switching to Sattelite and would like the installers to mount the dish to my chimney. Right now there is an aerial antennae (no longer used) that has the cable going straight through the roof just down-hill of the chimney. As a side note, the previous owners, in their infinite wisdom somehow managed to loop this cable around the chimney on it’s way the basement…make it it pretty much impossible to snake a new cable through.
Right now the chimney has a metal flue that’s being used to exhaust the gas furnace and water heater.
The dish installers said that their biggest issue in terms of location is getting a ground to the electrical panel, so they’d like to install it right on the edge of the roof near the electical in.
I’d rather not do this as it’s rather ugly right there, and it involves attaching more things to the roof (which I will eventually be re-roofing in standing seem metal).
I was wondering if it is a good/bad idea just to run the coax and ground down the chimney? This would solve a few problems (would get rid of the hole(s) in the roof and would be super-easy to snake a wire down such a large open ‘chase’ to the basement.
Anyone want to say if this is a smart idea or a total idiotic idea?
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First of all, why mount it up high???
At times, LNBs and connections do fail, and they are MUCH easier to replace when the dish is mounted on the ground.
I don't know the NEC, don't know grounding, don't know much. But it has been argued to me (quite logically too) that a grounded dish up high will act as a lightning attractor. (Think lightning rods on old barns)
Some guys argue for grounding, because the NEC says so. Others argue against it for valid reasons. I have yet to hear anyone argue for it for a reason that makes sense to me. (so if anyone else is reading, I would like to hear it, just for personal knowledge)
I say mount the dish low (on a metal pole)- the dish is actually designed to mount on a run of the mill chain link fence post.
THe ONLY reason I can justify mounting a dish high is to clear some obstacle (trees, for instance).
Help much? I didn't think so.
I'll be interested in following this to see what people that know more about grounding have to say . . .
*I'd be interested in hearing more about the grounding issue too. It sounds like if I want them to install it (to get the free installation) they NEED to ground it to the electrical panel. As for mounting it on a pole, that's really just an aesthetic reason. We have a small-ish urban yard and the pole would have to be rather high to clear some of the trees out front and it'd have to be quite close to the front of the house to clear the neighbor's. Plus there's always kids in the yard and the pole would just invite trouble. ;o)I was thinking that the chimney would be an easy install, as there already is a pole strapped to the chimney for the aerial. That said, you have a good point about needing to access it if the coax goes bad.One solution may be to have them mount it on the garage. There is a panel in the garage that they can ground, and I don't care as much about the garage roof. The only catch there is that I'll have a cable running between the two structures until I get around to burying the line.
*Mine is grounded to a grounding rod which they installed directly under the dish. Whats the difference in the existing panel ground or just installing a new rod?
*Darrel1-I understand your aesthetics concerns. Where do you live?? The signal actually comes in pretty high above where the dish "points" (22 degrees higher actually). Due to the offset of the LNB arm, the dish sort of points "below" where the signal is coming from. Just FYI- maybe that tall pole isn't really needed. But I haven't seen your house or know anything about the location. If you're in a middle lattitude of the US though, the signal actually comes from pretty high up. And you're probably right about the free install requiring that ground. But if you're handy and it's a single slot dish, the install is a breeze. (If it's a multi slot dish, a little harder but not much)Geoff-The requirement for the ground to the main service panel is due to a requirement in the NEC (I think). Code dictates that all grounds must be bonded together somehow so as not to create an imbalance in ground potential. It is my understanding that imbalances in the ground potential can cause some nasty consequences under certain circumstances. And imbalanced grounds can also cause ground loops. They cause funny wavy lines in the sat picture and can distort picture and sound in other ways.Bear in mind, I'm not a pro electrician and this is all based on my somewhat primitive understanding of electricity and the NEC. So take this advice for what it's worth. And consider what it cost you . . . . . I'm anxiously awaiting someone else to chime in and offer some real advice. . . . .
*In the building I oversee, I've probably got three dozen satalite antennas, a new one gets installed every month, all from different companies.Some are real hyper about finding a ground and want to wire into the ground wires of the in-room heaters that sit under the windows (I say no)Some drive a ground rod right outside the room and others just say screw it and hook it up without any ground. One guy "grounded" the thing by screwing a wire to the metal window frame.All work exactly the same.
*the outside unit is low voltage dc power, so the nec ground rule does not apply, the grounding is for lightin strike. So a ground rod will work.
*On a different front: mounting stuff to chimnies often isn't that great an idea; usually when I see chimney mounted equipment the chimney needs repointing and other repairs. Antennae and dishes and whatnot can put undue strain on the chimney structure.Masonry repairs don't come cheap these days!
*Well, right now, we have an ungrounded aerial on the top of our house, which I'm sure is more 'iffy' than an ungrounded dish. I'm not sure on what the benefit of a grounding rod would be if the dish is on the house...I'd still need to run a wire from the dish down the roof to the ground.Bob...valid point on the chimney. That said, the last (and ONLY) time I attempted to venture out onto my roof ridge, the chimney looked to be in good condition. The current aerial is strapped to the chimney and appears to be solid. (that said, I'm assuming these dishes aren't that heavy...I may be wrong.)At this point, I guess I'm just wondering if I should even be considering dropping the coax and ground down the chimney. The 5" flue gets uncomfortably hot going into the chimney in the basement, but I can't imagine it is hot enough to potentially melt the coax or anything.Chris: I'm up north in the Twin Cities, MN, so the dishes here are pointing rather low. Most are screwed directly into a window frame on the front of the house. REALLY tacky, IMHO. The problem is we have a bushy maple in front of our house, and the yard next to us has apple and pear trees, so we need to be at least 10' to clear everything, at which point a pole becomes rather awkward.At this point, I'm thinking that I'll just have them put it on the edge of the roof where the installer wants it a worry about moving it when I get around to redoing the roof.
*If it is somewhere where it might get hit or a near miss by lightning, the ground rod is good, but there are a few things to look out for. Lightning tries to take the lowest resistance path to ground, if that's through your set top box, too bad. You need to have a lightning arrester on the coax, preferably before it enters the house. (You are trying to keep the lightning energy out of the house where it can get into power and phone wiring.) The ground wire from the arrester needs to be run directly to the ground system. Note that if the electrical route through your power service ground is better than the arrester ground, the energy will tend to go through the house power wiring, creating havoc. With the dishes, usually they are mounted lower than other electrical conductors, so the chance of a direct hit is small. However, a long run of cable can pick up a pretty good voltage by induction from a near miss. I currently have my dishes lag bolted low on the gable end of the house. As a ham, I have a lot of other more attractive conductors in the air around the house.Erich
*OK...now I'm taking this a bit further off topic...How important IS it to have a grounded 'lightning rod' on the house? Right now, the high point on the house is an aerial antennae not connected to anything. (when we bought the house, it was connected to the cable system...I felt that was worse than not connected to anything). There are a few trees and houses withing 100 feet that are taller.
*I tried to avoild this, but I don't see anybody offering any real information so I will add to the confusion.First I would never allow anything in an active flue, neither the ground wire or the signal cable. Just too much corrosive gases to be good for anything. And that includes the dish. If you can mount it on the side of the chimney or on a pole so that it is several feet above the top. As far a ground it serves several purposes. First you can have large static buildup due to the charges in the clouds. IF you have a good ground through all of cable and equipment then it can bled off to ground. But with many items not having a ground power connections then there is a good chance that the build up will discharge through your TV equipment. However, that build up could be safely handled by a ground within the house.Another purpose is to handle direct lighting strikes. It doesn't matter. Nothing of this type will handle those.Next you have induces spikes from near by lighting. That can induce currents that are are too big to safely carry through the house wiring and a direct external ground run is best. But is this a "real problem". It depends on your location.
*Eric did a good job of describing what I was trying to say in my explanation of imbalanced ground potential. I wouldn't run through the flue. I also wouldn't ground the dish. Nothing you do will protect against lightning. And static buildup is better protected against with a high quality surge suppressor at the set top box. A good one is several hundred clams, and be sure to get one that protects coax, ac voltage, AND telephone as your box will more than likely be connected to the phone system also. Twin cities incidence angle is pretty low, you're right. Now I understand the need to get the dish high to clear the trees. You're also right that the dish is lightweight, re: mounting to the chimney. I don't think the problem is so much the weight of the dish, but also the wind loads. One of those things will load up pretty good in a stiff breeze. That's hard on mortar joints. And they load up more than an antennae due to their solid construction.One more thing I forgot to mention, and it's irrelavant to your question, but you need to be able to reach the dish with a broom or something in the winter time. Snow buildup on the dish will block the signal. And if you get a wet and heavy snow, it doesn't take much of the sticky stuff. Light powder snow isn't much of a problem. But those late winter storms that drop a couple inches of wet snow can block the signal. For running the coax- do you have vinyl siding?? The RG-6 can be tucked into the corner piece of siding for your vertical run to the ground. Pretty good hiding spot, and solves the chimney problem. Maybe. FWIW. Good luck.
*I'd just trust the professionals that write the National Electric Code.They say that "Masts and metal structures supporting antennas shall be grounded...." Paraphrasing: the grounding conductor shall be connected to: the nearest accessible location on the building grounding electrode system,the water piping system w/in 5' of where it enters the building,a metallic service conduit, or the service equipment enclosure.The grounding conductor from the dish has to be at least #10 copper and if you use a separate grounding electrode for the dish,you're supposed to have at least a #6 copper jumper from it to the building grounding electrode system.This is part of what the engineers that study lightning protection require,but of course, people come up with reasons everyday why the NEC doesn't apply to them.Darrell, I agree with Bill that the flue route probably isn't a good idea.And on the edge of the roof,with Minnnesota snows? Not much better.Are the installers just looking for the shortest, easiest path?I tucked mine right up under the gable end eave.I was worried about the neighbor's trees but I was suprised how easy it was to get a good signal.
*i Are the installers just looking for the shortest, easiest path?That's my guess. Well, Chris's point is perhaps the most persuasive...I need to be able to knock snow out of it in the winter...so I'm throwing out the chimney idea.I wouldn't MIND it on the side of the house, but we have stucco siding, and I'm not sure if I trust the guys to mess with that (maybe I'm just paranoid...)I'm thinking I may have them throw it on the garage roof and just run the cable to the house. There's a panel in the garage they can ground it to and we already have cable going from the alley to the house, so what's one more? BTW, here's a picture of the house...
*Contrary to what has been said here, electronic equipment can survive direct lightning strikes. It just takes some serious protective measures. Out west here, mountaintop radio sites get multiple lightning hits each summer. To prevent having to reinstall (and pay for) the equipment, tough measures are used to prevent damage. All conductors entering the building are routed through what is called a grounding window. This is usually a copper plate mounted on the building near ground level. This is bonded to the main ground. All power, phone and coax cable lines go through this plate via a lightning protection devices (see http://www.polyphaser.com). This prevents the lightning energy from entering the building and frying the electronics inside. This prevents the expensive electronics from having to be replaced, however, often the cables outside have to be replaced. Hope this helps.
*I think phone lines are can lead to more lightning problems than things sticking out of your roof.I have a solar electric house/totally off the grid here in WV.Came home late in Dec. after a wierd winter thunderstorm and smelled that unmistakeable burnt electronics smell.No lites no phone no AC.Turns out ligtning hit in woods near my phone line(2700' which I have to maintain since Im 1000 ft off state road) about 2000 feet from house.Ran up phone line to house leaving about 6 spots where it looked like you tied an M-80 to it. The juice went into the back of my fax machine[via phone line) and out the AC line and down to my Trace inverter frying it($1000)!I agve up on answering machine here for the same reason and have Verizon do it for me.But othewr than that if storms are even predicted 40 miles away I physically pull the plug.Interesting aside to this...my girl friends house got hit by a near strike and besides all the electrical damage on wall one it drove every drywall nail back out of the studs so that the whole wall looked like a pin cushion??!!
*Treetalk has an interesting point. You need to put lightning protection on every conductor that enters the house, power, phone, cable, etc. A strike can come in on anything. Watch out for metallic clotheslines!