Grounding to heat pump chassis: OK? [Archive]

Coffey77

10-09-07, 11:13 AM

Depending on what type of pipe is connected to your heat pump, copper or galvanized or PVC (I doubt it's PVC but I've seen it). Check the pipe that feeds your house as well and make sure that it is copper as well, if it is at all. Mostlikely, the pump motor is grounded through it's power supply and back to the panel which more than likely is also grounded to the casing of the Heat Pump. There is a chance of some signal distortion but if the correct size ground wire is used, there shouldn't be much issue. If you do have issues, that is definately a place to start looking. :)

davejacobson

10-09-07, 11:23 AM

while the chassis on the heat pump may be grounded it is not the proper place to ground your dish. The electrical box for the heat pump may be a good place but I am not so sure about that also. The ground should go back to main ground at your service enterance. There are very few exceptions. Chassis on a heat pump is not one of them.

joe diamond

10-09-07, 11:43 AM

I sat through an installer meeting on the subject. The national code says within ten feet of the entrance hole, bond to the main electric ground rod. I think the meeting devolved on the concept.." you explain to corporate why these jobs are not going in.....use the best ground available!" I am not sure the AC chassis is better than nothing. It will probably be fine unless your heat pump shorts out and blows your receiver.

Good question,

Joe

Coffey77

10-09-07, 11:49 AM

The problem I see with it is that what happens if the Heat Pump gets removed from the pipe for maintenance/whatever... Then you've lost your ground and can only rely on the installer when the new equipment goes in. It is a better idea that it is brought back to the panel or attatched directly to the copper water service pipe entering from outside.

mchaney

10-09-07, 11:50 AM

I could easily just pound another grounding rod into the ground there and connect it to that. Is that acceptable, or does it have to be the same grounding rod that feeds the ground to the house?

Edit: just measured the AC voltage between the heat pump chassis (while running) and the ground post of the 110 AC outlet right next to it. I got about 80 mV. I then put one lead on the ground post of the 110 outlet and stuck the other lead in the dirt right beneath it. 350 mV. Not sure what any of that means?

Mike

JeffBowser

10-09-07, 12:12 PM

What do you get when you measure from the neg probe of the meter to the pos probe ? It may mean nothing if your meter is not calibrated. If it reads zero, then my take is you have a ground loop, that your heat pump may not be bonded to the rest of the house. Along those lines, no, do not use a separate ground rod for your DirecTV system, unless you also bond said rod back to the house.

My DirecTV system is bonded to my pool heat pump. Plastic pipe or no, I watched it being wired, and the pump was bonded to the house ground, and the chassis, and all metal parts of that pump was also bonded to the house ground via jumpers. Exactly following NEC code is not always possible in situations like this, any ground bonded to the house ground is better than no ground, or a separate ground.

I could easily just pound another grounding rod into the ground there and connect it to that. Is that acceptable, or does it have to be the same grounding rod that feeds the ground to the house?

Edit: just measured the AC voltage between the heat pump chassis (while running) and the ground post of the 110 AC outlet right next to it. I got about 80 mV. I then put one lead on the ground post of the 110 outlet and stuck the other lead in the dirt right beneath it. 350 mV. Not sure what any of that means?

Mike

40-Dan

10-09-07, 12:24 PM

I could easily just pound another grounding rod into the ground there and connect it to that. Is that acceptable, or does it have to be the same grounding rod that feeds the ground to the house?

I'm not an electrician, but I THINK that you are supposed to then bond the new rod with the one your electrical service is attached to.

Can anyone back me up on that?

JeffBowser

10-09-07, 12:30 PM

Backed up in post #7 above

I'm not an electrician, but I THINK that you are supposed to then bond the new rod with the one your electrical service is attached to.

Can anyone back me up on that?

mchaney

10-09-07, 01:05 PM

After reading the responses, I think my best bet might be to buy a little longer length of grounding wire and feed it the extra 10 feet to the house's ground rod directly. It'll be a little less "perty" as I'll have to go up over a short (~3 foot tall) wall to get to it, but that might be the best and safest hookup.

Mike

n3ntj

10-09-07, 03:04 PM

I noticed that the installer grounded my dish with a screw to the side of the heat pump. Is this OK? Might this cause interference or signal loss when the heat pump turns on/off, or is that an OK ground spot?

Thanks,
Mike

Absolutely NOT PERMITTED per National Electric Code! Call D* or the installer directly and have it corrected immediately to meet your local codes (which probably is the NEC).

The dish and block should be grounded to the electrical system's ground rod using a separate grounding terminal clamp. Each wire connection to a ground rod must have its own dedicated grounding terminal clamp. IF the dish is not near (more than 6 meters or approx. 22') the electrical system's ground rod, a 2nd ground rod (8') can be installed and must be fully inserted to obtain 8' of continuous ground contact. If the 2nd ground rod is used, this new ground rod must be bonded to the electrical system's ground rod using at least 6 AWG copper.

The NEC is very clear about what is required by code (in most areas) for satellite dish installations.

techrep

10-09-07, 04:31 PM

What should be done: One #6 bare copper ground wire from dish to grounding block to it's own ground clamp on the house ground rod.
What may be done: One #6 bare copper ground wire from dish to grounding block to it's own ground clamp on a copper or steel cold water pipe.
Anything else is a compromise.

Phlakey

10-09-07, 04:38 PM

The heat pump housing is grounded via the ground wire for that circuit. The main reason for grounding the housing is to transfer fault current back to the breaker. (Picture a bare wire in the unit that might come into contact with the housing.) Without the equipment ground in place, the housing could become energized, and if touched by a person, could use that person for a ground path, resulting in a nasty shock. The equipment ground should only ground the equipment the circuit is connected to.

By grounding your dish thru the heat pump, you could subject your receiver to damage if there is fault current in the heat pump. (Here in Texas, fire ants make the contactors blow up all the time.) Plus it is a violation of the National Electric Code. If the situation reverses, say lightning hits your dish, your heat pump (and who knows what other electrical in your house,) would likely be fried.

I believe the main reason for grounding the dish is to protect against lightning. A new ground rod, or a copper water pipe are good clean locations for grounding. Whatever your electrical panel is grounded to is preferred, but not always possible. The intent is to provide a direct path to ground without the current running through any expensive equipment.

And remember, if you get struck by lightning, it's going to take the path of least resistance. This is impossible to predict, and usually results in damage to something in the house.

Meglos

10-09-07, 05:55 PM

(Here in Texas, fire ants make the contactors blow up all the time.)The first time I read that, I read "contactors" as "contractors" and was wondering if I could mail-order some fire ants. :)

mchaney

10-09-07, 06:13 PM

The first time I read that, I read "contactors" as "contractors" and was wondering if I could mail-order some fire ants. :)

If you need any, just let me know. I've got a yard full of 'em here. :rolleyes:

Mike

NR4P

10-09-07, 06:29 PM

The reason for grounding is to provide lightning or other high voltages the shortest possible path to ground.

By going to another device first, you are creating a path to ground through the heat pump chassis. So now if lightning should hit, not only does it take out the dish, it takes out the heat pump too. (Alternatively the heat pump develops a problem, now your dish is part of the problem such as 220v floating around it).

While all items could have a common ground point, they should have the absolute shortest, direct distance to the point.

bwaldron

10-09-07, 06:37 PM

If you need any, just let me know. I've got a yard full of 'em here.

Yeah, I've got "extras" as well ;)

K4SMX

10-09-07, 06:40 PM

I could easily just pound another grounding rod into the ground there and connect it to that. Is that acceptable, or does it have to be the same grounding rod that feeds the ground to the house?..........

Mike
Much better idea. Run a piece of #4 solid copper straight down to that new ground rod. Then run a piece of #6 from the new ground rod to the nearest point which is definitely bonded to your service ground, preferably at the service ground itself.

And how about your coax? Where does it go? It shouldn't provide a separate lightning path, but should also come straight down to your new ground rod location, and then through a grounding block, which is bonded to everything else there. Then you can send the coax wherever it needs to go.

mchaney

10-10-07, 06:27 AM

Much better idea. Run a piece of #4 solid copper straight down to that new ground rod. Then run a piece of #6 from the new ground rod to the nearest point which is definitely bonded to your service ground, preferably at the service ground itself.

Does the wire really have to be that thick? I've always used something on the order of 10 gauge in the past. Sounds like that might not be thick enough?

Mike

JeffBowser

10-10-07, 06:37 AM

My take on this is you have high value, high risk, and/or commercial systems that need as good of protection as available for various reasons (legal, safety, reliability). This is where Stew is coming from, I believe. On the other hand, we have here a large number of do-it-yourselfers who are trying to put something together that was either left undone by DirecTV installers, or screwed up by them, and often adhering to the NEC is either impractical, or cost prohibitive. We're (in my opinion) mostly concerned with bleeding static build-up and protection from system shorts. #10 wire will do this. I use #6. I've found #4 to be too much for me, and I have no illusions that my grounding system is gonna ever be able to handle a large current sink - my wallet is gonna have to handle that one :lol:

Does the wire really have to be that thick? I've always used something on the order of 10 gauge in the past. Sounds like that might not be thick enough?

Mike

bt-rtp

10-10-07, 06:55 AM

Grounding to the heat pump chassis is not OK. No way. The link below has the information on proper grounding.

http://www.dbstalk.com/showthread.php?p=941620#post941620

Learn it, know it, believe it.

JeffBowser

10-10-07, 07:01 AM

You are absolutely, technically correct. However, this kind of one way, and one way only thinking results in many installers and homeowners just giving up, and not grounding at all. Not good. If I were to directly follow the NEC at my house for my dish, my dish would have to be moved, to where I have no LOS. I have no cold water pipe accessible within 100 yards. There is ideal, code, and real-life. It's nice when they all come together, but they can't always.

Grounding to the heat pump chassis is not OK. No way. The link below has the information on proper grounding.

http://www.dbstalk.com/showthread.php?p=941620#post941620

Learn it, know it, believe it.

mchaney

10-10-07, 07:12 AM

Last night I disconnected the heat pump connection and ran #10 copper straight from the dish to the grounding pole by the utility box. Total run length was about 15 feet. I do think grounding it to the heat pump might have been causing some signal blips. With it attached to the heat pump, I'd get pixelization/freezes once in a while in perfect weather even though my signal strength is mid to upper 90's on all (valid) transponders, even the 103 bird. One of the reasons I moved it is that I thought that the blips might be happening when the heat pump turned on/off. The motors in those things draw a LOT of juice and if you ever watch them with the relay panel open at night, you'll see what a spark those things make: it's like an EMP. :) Anyway, I thought that with the dish connected to the chassis of the heat pump, there could be some electrical or EM noise pops when the thing cuts on/off. Now with it grounded to the grounding block of the house, I watched my first hour or so of live TV without any of those pixelization/freezes last night. It think grounding it properly might have helped. Or... it's just my imagination.

Mike

JeffBowser

10-10-07, 07:20 AM

That's terrific. Actually sounds to me as if the heat pump itself may not be properly grounded. Its current draw on startup should have no impact on ground. Anyway, you now have a more technically correct ground, and that's always a good thing when possible.

K4SMX

10-10-07, 07:44 AM

Does the wire really have to be that thick? I've always used something on the order of 10 gauge in the past. Sounds like that might not be thick enough?

Mike
Don't scrimp on the #4 from the dish to the ground. Actually, copper strap is better, but much harder to find. You can easily obtain #4 in 25' boxed lengths at Lowe's/HD, etc. or any electrical supply house, along with the special, split-U fittings to join one piece to another. They also have 8' copper-clad steel ground rods with fittings for #4. Ground rods are cheap, and if your soil is not too rocky, adding more ground rods is an excellent idea. If you can only get 4' into the ground, two 8' rods cut in half, with all 4 lengths driven in the ground in a ~2' box pattern, are better than giving up.

The #6 bonds your antenna's grounding system to the utility service ground. The purpose of this is to prevent equipment-damaging transient voltage differences between two or more points in your home wiring generated by nearby lightning strikes from damaging your equipment. These current flows could be quite large on an instantaneous basis, hence the NEC requirement for #6. Since this is not strictly part of your direct lightning strike dissipation system, use of smaller size wire, while not "up to code", would be effective to a point.

It is always preferable to disconnect completely any equipment you really want to protect, but this can be problematic considering the numerous interconnecting cables between connected devices. TV's and computer systems are usually the easiest, and a little planning can make rapid separation from connected wiring not too onerous.

Please also see this thread, Do You Think Your Dish Is Immune to Lightning? Think Again... (http://www.dbstalk.com/showthread.php?t=103685), and post #58.

Jagg

10-10-07, 01:17 PM

My installer apparently didn't even ground my dish (i had no idea at the time what it was) and used my old old cable wires from almost 20 years ago. I can't imagine why i'm having 771 errors...

svcguy

10-10-07, 06:04 PM

The thought that grounding protects against lightning strikes is a common misconception. Lightning protection is an extremely difficult buisness, and should handled only by those specifically trained for it.

The bottom line is if your dish takes a direct lightning strike it really doesn't matter if it's #10, #4 or #000, you're gonna need new wire and a new dish afterwards :D . The main purpose for proper grounding and bonding is to keep any of those stray voltages/currents away from your equipment and out of your house, dissapate static buildup and prevent ground loops.

That being said, adhere to your local codes and use the best materials that you can afford. If you've got the dough for bigger wire, it certianly can't hurt :p . If in doubt, consult a pro.

K4SMX

10-10-07, 06:34 PM

The thought that grounding protects against lightning strikes is a common misconception. Lightning protection is an extremely difficult buisness, and should handled only by those specifically trained for it.....
If it is a "common misconception," it is one firmly held by "those specially trained for it." No one expects "protection" in the sense that nothing bad can happen. Rather we're talking about mitigation of damage.

ActiveHDdave

10-10-07, 06:34 PM

The first time I read that, I read "contactors" as "contractors" and was wondering if I could mail-order some fire ants. :)

Earwigs are bad on contactors, as are mouse nests. I have seen both.:eek2: :eek2:
Get a 10' ground rod and #4 solid copper that should be good and make sure your heat pump is properly grounded and for ****s and giggles check to see if your electrical service is properly grounded.
100amp service needs #6 solid copper from your panel to to 10' ground rod and to water pipe (BOTH) if it's copper coming into your house. Also water meter needs same copper wire on either side of meter to provide ground all the way to street. Some places require 2 ground rods or newer codes.
200amp services require #4 wire in the above locations.

Don't forget to disconnect the ground dish wire from your heat pump. but make sure your haet pump is grounded so when I come out to give you so nice cool AC so you can sit back and watch your D# in HD I won't get the shock of my life:new_Eyecr :hair:

gulfwarvet

10-10-07, 06:39 PM

correct me if i'm wrong, but grounding to an electrical appliance (which a heat pump is considered to be) isn't a very idea for when it's operational would that cause signal interference?

bt-rtp

10-10-07, 07:33 PM

Congratulations. Glad to hear that it's improved system performance as well.

gulfwarvet

10-10-07, 08:00 PM

Congratulations. Glad to hear that it's improved system performance as well.

huh?? :confused: to whom are your referring this post to? :)

svcguy

10-11-07, 06:59 AM

If it is a "common misconception," it is one firmly held by "those specially trained for it." No one expects "protection" in the sense that nothing bad can happen. Rather we're talking about mitigation of damage.

If your inferring that I'm a preaching lightning protection expert, I'm not :p . I just know that protecting from damage against lightning is a fairly specialized industry, and based on your location you probably well know. Lightning is gonna do what it wants if you take a direct strike. If it wants to cook all your equipment, it will. If it wants to raid your fridge and eat last nights pizza leftovers, it will. :D To protect against it, or mitigate it's damages, is serious buisness.

K4SMX

10-11-07, 10:06 AM

If it is a "common misconception" ("...that grounding protects against lightning strikes"), it is one firmly held by "those specially trained for it."......

If your inferring that I'm a preaching lightning protection expert, I'm not :p . I just know that protecting from damage against lightning is a fairly specialized industry, and based on your location you probably well know. Lightning is gonna do what it wants if you take a direct strike. If it wants to cook all your equipment, it will. If it wants to raid your fridge and eat last nights pizza leftovers, it will. :D To protect against it, or mitigate it's damages, is serious buisness.
That was, of course, not my inference. It is beyond question that people in the lightning protection industry believe that proper grounding of antenna systems to protect against lightning is essential. That is, in fact, their primary task with respect to any structure. There is an extensive literature on how they can more effectively create a lightning dissipation grounding system, to include special methods when dealing with solid rock substrate, chemical treatment of the soil, etc.

It's very dangerous to promulgate the idea, which I see all too frequently, that "grounding doesn't matter for lightning protection," or that no matter what you do, you're toast anyway if you get a direct hit, so don't bother doing anything. This is simply untrue and to post comments to the contrary is irresponsible. Grounding your satellite dish is not something to be complacent about, and this is a great time of the year for all dish owners to review their individual situations and make needed improvements.

JeffBowser

10-11-07, 10:30 AM

Surely you aren't equating private dish installs to commercial protection schemes ? There is no way the average Joe Dish-user is going to feasibly and economically achieve any real degree of lightning protection as defined by those who are tasked with protecting tall commercial communication structures. We're talking about some area in the middle here between outrageous faraday cage type grounding schemes, and physically and monetarily feasible grounding schemes for the average Joe.....

That was, of course, not my inference. It is beyond question that people in the lightning protection industry believe that proper grounding of antenna systems to protect against lightning is essential. That is, in fact, their primary task with respect to any structure. There is an extensive literature on how they can more effectively create a lightning dissipation grounding system, to include special methods when dealing with solid rock substrate, chemical treatment of the soil, etc.

It's very dangerous to promulgate the idea, which I see all too frequently, that "grounding doesn't matter for lightning protection," or that no matter what you do, you're toast anyway if you get a direct hit, so don't bother doing anything. This is simply untrue and to post comments to the contrary is irresponsible. Grounding your satellite dish is not something to be complacent about, and this is a great time of the year for all dish owners to review their individual situations and make needed improvements.

K4SMX

10-11-07, 10:54 AM

davejacobson

10-11-07, 04:44 PM

Last night I disconnected the heat pump connection and ran #10 copper straight from the dish to the grounding pole by the utility box. Total run length was about 15 feet.
Mike

Total distance to a proper ground was only 15ft! Wow I dont know what to say about your installer but it isnt good. Thanks for having (or getting) the knowledge your installer should have known and the brains to correct it. good job:)

svcguy

10-11-07, 06:30 PM

Surely not. What I am saying is that the standard NEC requirements, which are "feasible grounding schemes for the average Joe," are greatly preferable in mitigating lightning damage to sticking one's head in the sand and crossing one's fingers, and further, that even these minimal requirements can be easily and relatively inexpensively improved upon by the "average Joe," should he so desire.

+1, to that. I do however have to agree with Bowser that the NEC requirements have little to do with equipment protection, and more to do with fire protection and personal saftey (they are, afterall, published by the National Fire and Protection Agency). That's the main point I'm trying to get across. I'm not saying don't do anything at all, that's extremely dangerous. I'm saying that one simple ground wire won't protect your equipment from damage.

There is no lightning protection, mitigation, or whatever without proper grounding (energy must go somewhere). Don't confuse proper equipment protection with fire and safety protection, though. That's the difference between the NEC and IEEE Emerald Book and commercial systems.