Any issues with two power sources?

[Ira]

We broke ground last week on a new home. I'm trying to think ahead as much as possible, and I came up with this group of questions...
 
Here's the scenario... the new home is about 200' from an existing shop on the property. The shop will have its own electricity source (and meter), i.e., it is fed from a transformer that is on utility pole #1. The house will be fed from a transformer on utility pole #2. So I will have two transformers, two meters, two accounts with the POCO, etc. There won't be any high voltage wires running from the house to the shop or vice versa.
 
I do plan on running LAN cables, satellite dish cable (from house to shop), security/monitoring/automation low voltage wires (probably have a Elk hub or two in the shop connected to an M1G in the house), phone lines, etc. between the house and the shop. Although it probably doesn't matter, I will probably run a PVC water line from the house to the shop.
 
Will this cause any problems? For example, does it cause any problems if I have a LAN switch in the house connected to a LAN switch or wireless AP in the shop? Does it matter if the Elk hub and some M1G expansion cards in the shop are connected to a hub or the M1G in the house?
 
Any other potential issues/problems/showstoppers?
 
Thanks,
Ira

 

[kurtmccaslin]

I have a very similar set-up with network and HAI automation wiring between buildings.    For the automation wiring, the grounds need to be connected.   This is because the RS485 needs a common zero voltage to work.   
 
I had a lot of trouble with my system due to lightning damage.   I have replaced a bunch of automation and network equipment.   When lightning strikes near your home, you can experience a voltage difference between the two buildings that is big enough to fry your electronics.   I tried Ditek protectors on the LV wires and still had problems.   Probably due to inadequate earth ground.   Luckily I used 2 inch conduit between the buildings and was able to remove the wires and pull fiber.   I have had no problems since then.   
 
I live on a hill in the Texas hill country.   My problems may be more than most.   However, the fiber fixed my problems and was not too difficult to install for a novice.

I read somewhere on this board that the M1 does not work with fiber. It was years ago, and technology might have changed. Some of the other guys on this board might have experience with this.

 

[RAL]

I agree with @rockinarmadillo.  For your LAN, run fiber between the buildings.  That will help prevent lightning strikes from blowing up your network equipment.
 
Unfortunately, the Elk data bus doesn't work over fiber.   So if you're going to have the M1 cover both buildings, you'll need to run twisted pair for the data bus.  You'll need to put surge protection, such as a Ditek, at both ends.  I would recommend bringing the cable into both buildings at the same point as where your electrical panels are located so that you can have the shortest possible connection to the ground rods for the surge protectors.
 
In addition to the data bus surge protectors, put whole house surge protectors in both breaker panels.  The Eaton CHSPT2ULTRA is a good choice.
 
The separate AC drops from different transformers won't be a problem.  But you do need a common "ground" for the RS485 bus to work properly.  Note that this "ground" is not earth ground. It's the Elk DC NEG that needs to be common.  For the data bus, you only need 3 wires, Data A, Data B and NEG.  You don't need +12V since things will be on separate power supplies.   You could use a CatX cable for this, although you'd have a bunch of spare conductors (not a bad thing). 

 

[pete_c]

Relating to Satellite mount another dish on the outbuilding and use a autonomous receiver.

 

[LarrylLix]

I have to support the fibre optics cables or a dish WiFi system.
 
You don't want to have equipment electrically connected to equipment connected to both grounding systems. We have had farms and rural properties with many volts of differential flowing due to high voltage system neutrals grounded at both end of the county. When a high voltage system  fault  occurs (or lightning) on that system, your signal cable shields and common wires can evaporate as they try to keep two different earth ground potentials at the same voltage. The system will win and your equipment will lose. Cows have been killed by this phenomenon at times.
 
https://esgrounding.com/ground-potential-rise.html
 
Opto-isolator equipment can work for very small induced faults but can get expensive and technically difficult if high voltage isolation transformers and not employed to feed the isolation equipment. I wouldn't run any copper between buildings.

 

[Ira]

I plan on running at least a couple of 2" PVC pipes underground between the home and shop, along with a couple of water lines. That should allow me some flexibility. I agree with fiber for the LAN connection between the two buildings.
 
The only time I've used fiber was for relatively short lengths, and so I was able to buy fiber that had the appropriate connectors on each end already installed. Is installing connectors on bulk fiber a DIY thing? Does it require any expensive tooling? Several of my LAN switches have fiber ports, although I don't know what type of connector is used.
 
It looks like RS485-to-fiber converters are available, starting at $150 and going up from there. However, I guess these wouldn't work for the M1G connection to a remote hub because of the shared ground requirement... right? Sounds like there's no solution for the M1G connection that doesn't include at least a ground wire running between the two Elk endpoints.
 
I have a whole house surge protector that I bought for my previous home and never installed that I will use on the new home. I don't remember the manufacturer/model, but I remember it was very heavy and cost over $500. I will buy something for the shop.
 
Unfortunately, the home-side location for the conduit between the home and shop, is located on the opposite end of the home from where the the electrical service entrance is located, about 130' away. I will have a subpanel that's only about 25' from where the conduit will leave the home.
 
I haven't had DirecTV for a few years, so I don't know what all is available for transmitting signals. Maybe I can transmit from a DVR in the home to a receiver in the shop over the LAN fiber connection.
 
LarryLix... I remember reading/hearing about something similar to the problems you mention when two different grounding systems are connected, which is what led to me asking about this. However, I wonder if this issue includes a single wire running between the two buildings for the sole purpose of providing a common negative 12V ground between the two endpoints (M1G and remote hub). I understand that the endpoints are on two different grounding systems, but is that a problem for the single low voltage negative wire? See RAL's previous comment.
 
Thanks,
Ira

 

[LarrylLix]

<snipped>
LarryLix... I remember reading/hearing about something similar to the problems you mention when two different grounding systems are connected, which is what led to me asking about this. However, I wonder if this issue includes a single wire running between the two buildings for the sole purpose of providing a common negative 12V ground between the two endpoints (M1G and remote hub). I understand that the endpoints are on two different grounding systems, but is that a problem for the single low voltage negative wire? See RAL's previous comment.
 
Thanks,
Ira

I don't really understand your question here but it is a problem for any conductor between remote earth connections.
 
Maybe a worst case but here is the scenario.  The 500kV transmission line traveling across your county has a fault due to a plane crash or lightning or tower insulator failure. The live conductor goes to earth at the point. Now compared to the source that ground level is at about say half of the line voltage ...250 kV. Your property lies between these two points and shares some of the voltage drop...say 500 volts.
 
Now you have a wire connected to ground or to ground via a powers supply that brings that earth level of voltage down the wire to the equipment you are leaning against and your feet are at the earth voltage level for the outbuilding. Who ya gonna' call? Sensitive communication inputs don't like it either and you will never know what happened. Later you find your small gauge phone lines are burnt off and shields for coax cables are melted or evaporated.
 
This is all reduced by having very conductive soil, a perimeter ground grid of ground rods every ten feet, common earthing from the two transformer neutrals, lessor distance between buildings etc.
 
We found when properties in the rural made a Faraday cage around their properties to eliminate ground rise potential to save their cattle from getting pokes in the mouth and the farmer's wife from getting pokes in the shower, that the problem just moves to the next farm.
 
I was involved in a lot of fibre optic systems between cities, but the outdoor cable fibres,  and the indoor jumpers were expensive to glass weld together back then. I am not sure how it is done now but the media converters are quite cheap. There are many different fibre optic styles involved bidirectional single fibres and dual in/out glass fibres.
 
Gigabit media converters
https://www.amazon.ca/10Gtek-Bi-Directional-Single-Mode-1000Base-Tx-1000Base-LX/dp/B06XPZ3XQK/ref=sr_1_8?dchild=1&keywords=fiber+optic+media+converter&qid=1605300737&sr=8-8
 
Fast Ethernet media converters
https://www.amazon.ca/Hundred-Converter-Ethernet-Transceiver-110-240V/dp/B08HWPRH4M/ref=sr_1_3_sspa?dchild=1&keywords=fiber+optic+media+converter&qid=1605300577&sr=8-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExMEwzRFFKUzNRR0wmZW5jcnlwdGVkSWQ9QTA5Mjc0NjExMzNXSlpLMkpUTTRDJmVuY3J5cHRlZEFkSWQ9QTA2MzY2ODIyV0tTUkZJMFY2QzM0JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

[Ira]

LarryLix... I'm trying to reconcile your comments with RAL's previous post that said... "The separate AC drops from different transformers won't be a problem.  But you do need a common "ground" for the RS485 bus to work properly.  Note that this "ground" is not earth ground. It's the Elk DC NEG that needs to be common."
 
I think you are saying that even though a common 12VDC negative "ground" running between the M1G (in the home) and a hub (in the shop) isn't an earth ground, it's still risky because ultimately that ground is connected to two different power supplies, one in the home and the other in the shop, that are on different transformers, thus different earth grounds, which makes the wiring susceptible to the type of catastrophic failure you described. Is that correct?
 
I wonder if there is a way that I can logically create a zone in the shop that can trigger something in the home via the fiber LAN connection that the M1G would ultimately think is a zone violation. For example, have a RIB relay in the home that is set up like a regular door sensor across the relay contacts. Have something in the shop that can detect a relay closure (i.e., a door sensor) in the shop, and send a command over the LAN to tell the relay in the home to close. In other words, some type of "mirror relay over LAN" setup so that the relay in the home reflects the status of the relay in the shop. I remember there was a company that had all kinds of relay boards for doing similar functions, but don't recall their name.
 
Found it... https://ncd.io/ National Control Devices. I'm guessing one of their mirror relay boards over LAN or wireless will work. Note that mostly what I'm interested in are door/window sensors, and maybe some leak sensors. Smoke, motion, etc., would be good if something similar can be done using their stuff, but it isn't a requirement at this point.
 
Thanks,
Ira

 

[LarrylLix]

LarryLix... I'm trying to reconcile your comments with RAL's previous post that said... "The separate AC drops from different transformers won't be a problem.  But you do need a common "ground" for the RS485 bus to work properly.  Note that this "ground" is not earth ground. It's the Elk DC NEG that needs to be common."
 
I think you are saying that even though a common 12VDC negative "ground" running between the M1G (in the home) and a hub (in the shop) isn't an earth ground, it's still risky because ultimately that ground is connected to two different power supplies, one in the home and the other in the shop, that are on different transformers, thus different earth grounds, which makes the wiring susceptible to the type of catastrophic failure you described. Is that correct?
 
I wonder if there is a way that I can logically create a zone in the shop that can trigger something in the home via the fiber LAN connection that the M1G would ultimately think is a zone violation. For example, have a RIB relay in the home that is set up like a regular door sensor across the relay contacts. Have something in the shop that can detect a relay closure (i.e., a door sensor) in the shop, and send a command over the LAN to tell the relay in the home to close. In other words, some type of "mirror relay over LAN" setup so that the relay in the home reflects the status of the relay in the shop. I remember there was a company that had all kinds of relay boards for doing similar functions, but don't recall their name.
 
Thanks,
Ira

That sounds correct. It can even be a shock hazard to humans depending on a lot of circumstances and Ifs.
 
Why not run your own power in the same cable to the sensing device and the contacts back. I don't use any commercial security systems but I am thinking of a MS for example where the plastic insulated case is high on a wall, and the remote building supplies the power and gets a contact back...absolutely no connection between grounds, and insulated by no metal case, and not reachable by humans or other devices.
 
You could even run your own 120vac inside the conduit to run a select and isolated bunch of equipment. Provide a remote ground for the involved equipment but ground the touchable outer metal case of the equipment to the local ground for human touch and insulate all circuits inside from the case. Not likely you would ever get more than a few hundred volts, even during a lightning strike at either end with proper standard  lightning distractions. (arc gaps, and grounding). With some thinking there are ways around small voltage islands that can be created in another building.
 
There are Ethernet to contact and vice versa boxes out there.

 

[BraveSirRobbin]

I've used the RLH products at work in the past for relay control over fibers.  Used this in a situation (quick fix) where I needed to have a 'hard wired' interlock solution independent of any software in a remote location.  You can even get bi-directional devices.  Not cheap.  I think I would come up with a home brewed solution before spending this kind of money just to monitor one relay.
 
https://www.fiberopticlink.com/products/fiber-optic-converters/
 
I also found another vendor, but still not cheap.
 
https://datainterfaces.com/content/frm220-ccf-datasheet.pdf

 

[LarrylLix]

There are many Ethernet to I/O module on amazon.ca but a WC8 board at each end may do the trick. You would have to fabricate a power supply at each end and a box to house them.
 
This is assuming you go with fibre to get Ethernet at the remote end which I would lean towards due to later ideas that pop up.

 

[kurtmccaslin]

I don't have a M1G but I have read on this board that there is a problem with communication over fiber.   The problem is related to incompatibility with the RS485 converters.   The OmniPro does not have this problem.
 
You don't need a common wire between the buildings if you use fiber, but you do if you use copper.  The RS485 converter will provide the appropriate reference ground voltage on each side.
 
If you go with fiber in conduit, you will need to use burial grade fiber.   Not the inexpensive patch cable type.   I went with pre-terminated fiber complete with a pulling eye.   You can search for pre-terminated fiber on the internet.   There were videos on how to lubricate the conduit, carefully pull it through conduit and how to cut the pulling eye off without cutting the fiber.
 
The fiber bundle comes in various shapes and sizes.   I can tell you how I configured mine if you would like.   I spent quite a few hours researching the options and it worked the first time.

 

[tmbrown97]

Hope I'm not too late here... haven't been around in a while.
1) For LAN, definitely use Fiber.  Your typical relatively-short distance solution would be multimode fiber, and your existing switches usually use mini-gbics so you buy the gbic that fits your need - in this case a gigabit multimode module.  If you don't want to muck with terminating the fiber, you can buy pre-terminated fiber in the right length and they have pull-heads that protect the actual termination.  Your connector types I think are usually SC. 
2) Skip the coax.  If you're using satellite, as Pete said above - you can just get a second dish at the barn - the company will never know or care that they're not totally interconnected and if they need to talk to one another, they'll do it over the fiber LAN.  OR - most of the newer receivers really only have one of them talking to teh satellites - the rest just talk to each other over the LAN - so either way you shouldn't need that.
3) For the Elk, it does have the ability to split the power from the data - you could put an Elk P212S at the remote location hooked to the local power supply - that'll have its own battery and inject power to everything downstream.  This is where it gets theoretical as I've never personally tried it - but I'd experiment with RS485 opto-isolator.  That would take care of your physical separation so you don't blow things up.  Obviously make sure you're doing the branch to the barn as a one-way branch with termination at the end and not a loop.  This may take some trial and error - or maybe reaching out to Elk to see if they have any guidance.
 
Just my $.02.  I may be trying this soon too - I'm in escrow for a house on some property with a barn some distance away - so maybe I'll be experimenting soon too!  Until I get conduit in place, I'm going to do 60Ghz microwave to the gate and barn, and the barn already has its own power pole just as you describe above.

 

[RAL]

3) For the Elk, it does have the ability to split the power from the data - you could put an Elk P212S at the remote location hooked to the local power supply - that'll have its own battery and inject power to everything downstream.  This is where it gets theoretical as I've never personally tried it - but I'd experiment with RS485 opto-isolator.  That would take care of your physical separation so you don't blow things up.  Obviously make sure you're doing the branch to the barn as a one-way branch with termination at the end and not a loop.  This may take some trial and error - or maybe reaching out to Elk to see if they have any guidance.

 
Over the years, I recall a number of people have experimented with RS485 fiber extenders on the M1.  I don't recall that any of them got it to work.  Spanky from Elk flat out said they wouldn't work.  The issue seems to be with the latency that the extenders introduce when switching the bus from transmit mode to receive mode. 

 

[Ira]

I think I overthought this. I was basing all of it on what I had done over 10 years ago at a previous home/shop combination (both were on the same utility power source). Given some of the suggestions here, I'm pretty sure I can do everything I want with a fiber LAN connection, a pair of fiber relay boards, and something like eKeypad on my iPhone to control everything when I'm at my shop. CQC will also give me some additional options. I don't think a hub or remote M1G expansion boards are necessary.

Thanks for all the suggestions.
 
Ira