adding surge protectors in LB connector
- Thread starter mikefamig
- Start date
It's a long message thread to read and easy to miss but I mentioned in message #70 that I drove a stake into the earth to ground the device.westom said:
We also talked about grounding to an AC outlet or tapping into the existing bonding grid at the AC power load center in the building and exactly what constitutes a good ground or "earth". The NEC states that anything with less than 25 ohms resistance to earth is good enough for them and less than 5 ohms is ideal.
Mike.
After rereading earlier posts, confusion exists. First, many early on accurately defined better earthing. That NEC requirement for 25 ohms is only for human safety; does nothing for transistor safety; is irrelevant in this discussion.mikefamig said:
The Ditek, I had thought, was the 'whole house' protector for the subpanel's AC electric. Every wire that enters the garage (I believe that is what we are discussing) must connect low impedance to the garage's earth ground. Apparently your garage did not have an earth sub panel making surge damage easy. Because those AC wires (and any other wire) entering any structure must connect to that one structure's single point earth ground.
Ditek you were discussing was for Ethernet. That too must make a low impedance connection to earth. Apparently you did earth it. But every other incoming wire is not earthed to the same ground. That means surge damage.
As others noted earlier, a wall receptacle safety ground is completely irrelevant to surge protection. I did not see where others mentioned it, but any ground wire inside a metallic conduit is (for surges) also not an earth ground (for surge protection).
PeteC pictured a defective earth ground in post 14 at
http://cocoontech.com/forums/topic/28008-adding-surge-protectors-in-lb-connector/?p=229755 .
That ground wire was coiled meaning ground has been compromised. Coil created a high impedance. Or, based in a discussion in previous posts, that wire has sharp bends.
Generally sub- panels have four incoming AC wires from the main panel. Two hots, one neutral, and one safety ground. In that case, it gets more complicated. Your earth ground must remain separate from incoming neutral and safety ground wires. And be connected to those wires by a 'whole house' protector specially designed for those extra connections.
Yes,confusion since we were discussing different items. I thought your Ditel was an AC panel; different from one for the main panel. All eight Ethernet wires must connect via that other Ditek to the same single point earth ground that all four (or three) incoming AC wires also connect to. Apparently the garage did not have an earth ground until you provided it. Therefore every incoming wire to that garage must be rewired/rerouted to connect to that earth ground - either directly or via a protector.
Garage and main house are viewed as if two completely different structures - each requiring their own earthing and surge protection systems.
You misread my statement, and replied with inflammatory and downright abusive tone, assuming items that you are not privy to.westom said:
If you care to have a reasonable and respectful commentary, so be it, but frankly, you have no idea as to my background, knowledge, or what I do on a daily basis, let alone degrees, certifications and what have you. If you want to have a frank and open discussion, so be it, but your statements clearly show you did not understand my statement, what the intent was and what the background is.
Good day
westom said:
Your posts make me think that you are trying to create confusion.
westom said:
Wrong, a low impedance conductor to earth is needed to protect both life and equipment. The 25 ohm is in reference to using a water pipe or other existing ground in a building regardless of it's intended purpose.
westom said:
Wrong
westom said:
Wrong, that is not what we are discussing, this is what you keep discussing. The topic of this thread is protecting an RS-485 data bus specifically.
westom said:
Your assumption....wrong again, the garage has a properly earthed sub panel.
westom said:
Off topic
westom said:
Imaginary other incoming wires
westom said:
We're all aware of this.....
Your posts are full of inaccurate statements, wrong assumptions and you are mostly off topic and they just keep getting longer. If you insist on talking about AC power and proper bonding then why don't you start a new message thread for that. You're derailing this conversation with your posts.
Mike.
pete_c
Guru
+++ :rockon: SDA & Mikefamig & Del
@Mike - unrelated to OP here yesterday took a drive in almost oldest vehicle after having replaced drive belts, water pulley, a couple of sensors (difficult to get to) on a few local expressways (for a couple of hours). I did also bring a USB connection to the front dash and updated all of the interior lighting to LED (it is very bright now inside and lights are much cooler). I was scared for bit thinking and feeling insecure a bit relating to my DIY fixing. Well the car ran fine slow and fast in the rain (mostly rainy yesterday) and for more than a couple of hours and mostly just felt good. Like an old shoe in a way.
@Mike - unrelated to OP here yesterday took a drive in almost oldest vehicle after having replaced drive belts, water pulley, a couple of sensors (difficult to get to) on a few local expressways (for a couple of hours). I did also bring a USB connection to the front dash and updated all of the interior lighting to LED (it is very bright now inside and lights are much cooler). I was scared for bit thinking and feeling insecure a bit relating to my DIY fixing. Well the car ran fine slow and fast in the rain (mostly rainy yesterday) and for more than a couple of hours and mostly just felt good. Like an old shoe in a way.
pete_c said:
Very nice, are we talking about the old TR? I hope that I was an influence in your getting it running.
Nothing brings out the kid in me like taking a ride in the old convertible or the old bike. When I'm sitting on the couch in front of the tv at night I feel all of my 61 years but when I'm riding the old motorcycle I shed at least half of them. Each year that goes by now it gets harder to work on the cars but still each spring I find myself out in the garage getting everything in shape for another season.
I guess that I'm just an old gear-head at heart.
Mike.
pete_c
Guru
Not yet but your posts have motivated me to get it running and using it in the next few weeks. I have charged up the battery for the Triumph so far and I am hoping that I can get it started without too much effort (well now after about 5-6 years of it sitting). Last time I looked at it was 2012; but I didn't start it.
I did a bunch of stuff over the winter on the bimmer really only drove it a bit in the last few months.
I did a bunch of stuff over the winter on the bimmer really only drove it a bit in the last few months.
pete_c said:Not yet but your posts have motivated me to get it running and using it in the next few weeks. I have charged up the battery for the Triumph so far and I am hoping that I can get it started without too much effort (well now after about 5-6 years of it sitting). Last time I looked at it was 2012; but I didn't start it.
I did a bunch of stuff over the winter on the bimmer really only drove it a bit in the last few months.
What year is the Bimmer?
pete_c
Guru
2001
The car's belts were old (2001) but not really worn (35K). I decided to DIY replacing both and in the process shattered the plastic water pulley during the early part of the year.
Well to I had a sticky cam shaft sensor; tried a cheap Ebay replacement which turned out to be junk and went to a BMW one which is now working well.
It will still do 140 MPH in just a few seconds and it feels solid when doing it.. (very quickly).
When I started to use it and it got warm here the hedgehog (FSR) went out.
That was a PITA to get too as it behind the glove compartment, vent, vent relay and above of the fuses and you have to kind of remove it blindly.
The Triumph is way easier to work on and I could almost do it blind folded as the 1960's one I had I learned about cars with (the 64 Grand Prix was almost new so there was nothing to do with it).
The car's belts were old (2001) but not really worn (35K). I decided to DIY replacing both and in the process shattered the plastic water pulley during the early part of the year.
Well to I had a sticky cam shaft sensor; tried a cheap Ebay replacement which turned out to be junk and went to a BMW one which is now working well.
It will still do 140 MPH in just a few seconds and it feels solid when doing it.. (very quickly).
When I started to use it and it got warm here the hedgehog (FSR) went out.
That was a PITA to get too as it behind the glove compartment, vent, vent relay and above of the fuses and you have to kind of remove it blindly.
The Triumph is way easier to work on and I could almost do it blind folded as the 1960's one I had I learned about cars with (the 64 Grand Prix was almost new so there was nothing to do with it).
pete_c said:Not yet but your posts have motivated me to get it running and using it in the next few weeks. I have charged up the battery for the Triumph so far and I am hoping that I can get it started without too much effort (well now after about 5-6 years of it sitting). Last time I looked at it was 2012; but I didn't start it.
I did a bunch of stuff over the winter on the bimmer really only drove it a bit in the last few months.
Let me know if I can be of any help, I was a professional mechanic in a previous life and with cars of that vintage. I haven't kept up with technology but am pretty good with point type ignitions and carburetors. I just recently bought an OBD II reader and diagnosed a bad O2 sensor on my 2003 Nissan so I'm just getting my feet wet with modern electronics in cars.
Mike.
mikefamig said:
25 ohms resistance does not define low impedance, does not define appliance protection, and does not define sufficient grounding. A less than 25 ohm reistance can also a high impedance. Relative distance always was the issue - not resistance and conductiviiy. Outlet safety ground also was irrelevant - contrary to your assumptions.
Protection not on incoming AC means an RS-495 bus protector may even make RS-485 device damage easier. Protection involves every wire entering a structure - especially every incoming AC wire. That 'whole house' protector in the house is essential for RS-485 protection - unfortunatley not on the garage side. Even an NEC properly grounded sub-panels can compromise protection; as explained previously.
Newly installed ground rods must be part of an existing AC elecriic ground. 14 or 16 AWG wire is irrelevant. Length of wire from each protector to garage or house AC electric grounds are ciritical. Separation between protector and Elk should be as much as possible (ie tens of feet).
Water pipe grounds (per NEC) are insufficient even for human protection. Furthermore, a water pipe ground can be high impedance due to solder welds and other factors.. RS-485 protector makes device damage easier IF AC electric (and that water pipe) is not integrated into a protection 'system'.
I am sorry this stuff makes you angry. NEC requirements do not define any device protection. You assumed 25 ohms resistance defines impedance - and other errors. Question was about interconnecting an RS-485 wire between two structures. Protection of an RS-485 bus between two structures must be integrated with protection on AC mains with earthing that exceeds NEC requirements. Both house and garage need 'whole house' protectors to protect the Elk and that RS-485 bus.
These well proven concepts do not change because popular myths are contradicted. Either you have technical questions or need not reply. 25 ohms says nothing about impedance or about RS-485 protection. AC electric (whole house) protection must be properly earthed in both structures to have RS-485 protection.
