Surge Protection

[gcimmino]

Forking this off to a new thread so it will be more easily found by others looking for surge protection info in the future.

As always, don't forget about surge when running wires underground between buildings.

What type of surge would one use on the RS485 bus? As we get closer to making this happen, I'm now seeing at least 3 runs of Cat5e in the 25' conduit between buildings:

1) M1 RS485 data bus connecting a DBH in each building
2) Thermostat RS485 data bus connecting RCS stats in each building to an XSP
3) Ethernet between buildings

How would one properly put surge protection on these lines?

Thanks

 

[gcimmino]

Any EEs that could speak to this?

I've found various surge products, all are for either Ethernet or RS422 connections. They all seem to be very similar in that they take RJ45 connectors and protect all 8 lines.

The one thing that I'm noticing is differences in "clamp voltage". Looks like the Ethernet stuff starts at 16V and goes up depending on whether there are higher POE voltages in the cable. However the 422 stuff is either 7.5V or 15V. Since the Elk's bus power is 12V, I'm guessing the 7.5V 422 protectors are for 5V data levels and not applicable.

All this aside, would an 8 conductor RJ45 protector with 15-16V clamping be the right thing to use for the Elk Data Bus and/or a RCS thermostat 485 bus?

Also, I'm guessing one would want one protector at the entrance in each building.

Here's some of what I've been finding:

ITW Linx
Tripp Lite

Thanks

 

[Digger]

Any EEs that could speak to this?

I've found various surge products, all are for either Ethernet or RS422 connections. They all seem to be very similar in that they take RJ45 connectors and protect all 8 lines.

The one thing that I'm noticing is differences in "clamp voltage". Looks like the Ethernet stuff starts at 16V and goes up depending on whether there are higher POE voltages in the cable. However the 422 stuff is either 7.5V or 15V. Since the Elk's bus power is 12V, I'm guessing the 7.5V 422 protectors are for 5V data levels and not applicable.

All this aside, would an 8 conductor RJ45 protector with 15-16V clamping be the right thing to use for the Elk Data Bus and/or a RCS thermostat 485 bus?

Also, I'm guessing one would want one protector at the entrance in each building.

Here's some of what I've been finding:

ITW Linx
Tripp Lite

Thanks

My opinion is to be very careful. A 15-16 V clamping could have a 10 or 20% +/- tolerance. The Elk bus is really about 13.5 Vdc. In theory you could clamp at the 13.5 and the product would not operate and it would take the bus down.

If it was strictly data line then these would be fine. POSSIBLY run your common and your data out. Use a supplemental supply in the outbuilding for the power. I would check with ELK tech support on this.

 

[gcimmino]

Well, got off the phone with tech support at ITW Linx. They say their clamping tolerance is +/- 5%, which would put the various Cat5 products with 16V clamping in the ball park.

http://www.itwlinx.com/products/subcategor...;subcategory=49

I'll get a couple and try them out and let folks know.

Unless Spanky suggests something else!

 

[Digger]

Well, got off the phone with tech support at ITW Linx. They say their clamping tolerance is +/- 5%, which would put the various Cat5 products with 16V clamping in the ball park.

http://www.itwlinx.com/products/subcategor...;subcategory=49

I'll get a couple and try them out and let folks know.

Unless Spanky suggests something else!

I was actually playing with MOV's at work today. I put 25 Vdc across a 18 V MOV with a 10% tolerance. After about 20 seconds the smoke started pouring out of it as it conducted. So at just 5 vdc over the high end tolerence it heated up enough to char itself and create a lot of smoke. Emptied the lab out a few minutes early for lunch

If you use an supplemental power supply make sure you do not adjust it (if it is adjustable) to high to compensate for the length of the cable. Once the magic smoke is out things never work right

 

[huggy59]

This unit is a 7.5V, but there are similar units with higher clamping voltages available at other sources... I'm just Googling - I've never used this stuff. This one has gas discharge for possible lightning strikes. $$$

http://www.telebyteusa.com/catalog/products/22nx.htm

 

[gcimmino]

Spanky, I posted this on the Elk forum back in April but haven't received a response, so I'm bumping this thread here.

I was reading the instruction manual for the Elk-950 and came across this note (my emphasis added):

NOTE: The POWER terminals may alternately be used for surge protecting data transmission wires such as a
keypad or zone expansion bus, as long as any measurable voltage on the two data wires is less than 24 volts.
Connect the data wires to the IN and OUT terminals while observing polarity using the A & B markings.

Can I take this to mean that putting a 950 on each end of my data bus run in each building is a good/approved way to get the required surge protection?

Thanks

 

[gatchel]

This company has surge protection for any type, any voltage, alarm, CCTV, 120V, etc. product you could ever need. .

http://www.ditekcorp.com/


There are several voltages available in many different configurations. Two wire, 4 wire, wiegand card reader, cctv coax and power, whole house, etc.