Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations Chriss Miller on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
What is the standard for underground cable and fuse boxes? 6
- Thread starter Snapper
- Start date
-
1
- #2
- Thread starter
- #3
-
1
- #4
-
1
- #5
franklin97355
Technical User
Because they don't break the circuit when tripped but will shunt large spikes to ground thus protecting the equipment beyond them.
-
1
- #6
-
1
- #8
AvayaNovice
Vendor
Protectors on each end are a must. The cable you're using should have a metal layer on the outside too which needs to be grounded. The best way to do that is to cut the cable along its length in about six spots for 2" so that it looks like a bananna peel. From there, you can take a grounding strap around the grounding/protection layer and take it out of one of the parts you've peeled back, then tape the floppy ends back around the pairs so that it's tight again.
Protectors are what you see at MPOEs from the Telco, or most any underground/aerial situation. Avaya makes decent protectors that are more usable for customer plant.
Whoever said to get protectors designed for digital phone switches was right. MPOE protectors may not support the voltage and differences in signalling like a specially designed protector would.
Executone -- grounding unused pairs is kind of overkill. Remember that electricity chooses the path of least resistance to ground, a pair isn't going to help you there. The metal sheath will work just fine, and also if you ground those unused pairs you may be susceptable to interference if anything hits your ground circuit.
Bottom line, play it safe -- get the right equipment, make sure to clean the sheath with goo gone or some other industrial cleaner so that you get a good connection.
Protectors are what you see at MPOEs from the Telco, or most any underground/aerial situation. Avaya makes decent protectors that are more usable for customer plant.
Whoever said to get protectors designed for digital phone switches was right. MPOE protectors may not support the voltage and differences in signalling like a specially designed protector would.
Executone -- grounding unused pairs is kind of overkill. Remember that electricity chooses the path of least resistance to ground, a pair isn't going to help you there. The metal sheath will work just fine, and also if you ground those unused pairs you may be susceptable to interference if anything hits your ground circuit.
Bottom line, play it safe -- get the right equipment, make sure to clean the sheath with goo gone or some other industrial cleaner so that you get a good connection.
-
1
- #9
daronwilson
Vendor
I prefer to protect at both ends, but just to play the other side, suppose you have a 200 foot cable bonded to ground at one end. Now if it takes a lightning hit in the middle, where do you think the electricity is going to go? Least path of resistance to ground, so it is going to the protector to find a ground.
There are two kinds of protection, primary and secondary. Remember you first need to protect for life safety, you don't want anyone to get electrocuted (primary protection). Also, you dont want to hurt the equipment (secondary protection). It is always prudent to protect both ends by bonding the shield to ground and installing protectors.
There is no reason to split the jacket for 12" as previous stated. To properly install a ground stud on 100 pair, you should not have to split the jacket and shield more than about 4". Here is the drill:
Carefully slit the jacket 3-4". Take your trusty electrical tape and make 10-20 wraps around the wires where they come out of the jacket. The trick here is to wrap the tape with the sticky side out and not overly tight. Make this 10-20 wraps spread out over about 2". So now we have a 4" split in the jacket, and a black tape sleeve around the wires with the sticky side out. Pull the wires away from the metallic shield and punch a hole in the shield. Install the stud clamp so that the teeth bite solidly into the bonding shield and tighten the nut down on the outside clamp. Now, slide the black tape down on the wires so that the inside of the grounding clamp rests on the black tape pad (protects the wires). Carefully pull the 4" of outer jacket back around the wires and carefully tape it up.
Regarding protectors, the MPOE protectors WILL support the reduced voltages on digital sets. However, they will not provide adaquate protection to the set or circuit card. The other choice is lower voltage protectors that are designed for digital circuits (often red). They clamp down on lower voltages than the standard black protectors. Just remember if you move jumpers around that you may need to change protectors. An analog phone on a digital protector will work, but it won't ring since the protector will clamp down at a voltage lower than the ring voltage.
I'm sure you realize it, but the protector housing should be grounded to the building ground with #6 copper wire and this run should be as short as possible.
Good Luck!
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
There are two kinds of protection, primary and secondary. Remember you first need to protect for life safety, you don't want anyone to get electrocuted (primary protection). Also, you dont want to hurt the equipment (secondary protection). It is always prudent to protect both ends by bonding the shield to ground and installing protectors.
There is no reason to split the jacket for 12" as previous stated. To properly install a ground stud on 100 pair, you should not have to split the jacket and shield more than about 4". Here is the drill:
Carefully slit the jacket 3-4". Take your trusty electrical tape and make 10-20 wraps around the wires where they come out of the jacket. The trick here is to wrap the tape with the sticky side out and not overly tight. Make this 10-20 wraps spread out over about 2". So now we have a 4" split in the jacket, and a black tape sleeve around the wires with the sticky side out. Pull the wires away from the metallic shield and punch a hole in the shield. Install the stud clamp so that the teeth bite solidly into the bonding shield and tighten the nut down on the outside clamp. Now, slide the black tape down on the wires so that the inside of the grounding clamp rests on the black tape pad (protects the wires). Carefully pull the 4" of outer jacket back around the wires and carefully tape it up.
Regarding protectors, the MPOE protectors WILL support the reduced voltages on digital sets. However, they will not provide adaquate protection to the set or circuit card. The other choice is lower voltage protectors that are designed for digital circuits (often red). They clamp down on lower voltages than the standard black protectors. Just remember if you move jumpers around that you may need to change protectors. An analog phone on a digital protector will work, but it won't ring since the protector will clamp down at a voltage lower than the ring voltage.
I'm sure you realize it, but the protector housing should be grounded to the building ground with #6 copper wire and this run should be as short as possible.
Good Luck!
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
AvayaNovice
Vendor
As I stated above, 2" was the amount needed to be stripped back. 3-4 will work as well, but 2 is fine.
When talking about "reduced" voltages on digital sets, this is not the case in all phone systems. Some phone systems are different and I've seen digital sets not work at all as a result of this, and after checking the protector -- that's where the problem was.
Indeed, protector needs to be grounded... otherwise what's the point.
As far as the method for installing the grounding strap, you could do it that way I guess. I like doing the bannana peel method more because you can get it accurately and fully enganged, and then you seal the cable sheath back over after you're done. In most ARMY and Telco installations, this is how it's done. But to each his own...
And rather than using your "trusty" electrical tape on the post wrap job, I'd reccomend an electrical PVC tape. I can't remember what the brand name is, but there are a few brands that will provide outstanding weather protection, and they'll also stick through any icky pick or cable insulating gel.
Depending on how you're doing your splice, many different applications may be correct.
When talking about "reduced" voltages on digital sets, this is not the case in all phone systems. Some phone systems are different and I've seen digital sets not work at all as a result of this, and after checking the protector -- that's where the problem was.
Indeed, protector needs to be grounded... otherwise what's the point.
As far as the method for installing the grounding strap, you could do it that way I guess. I like doing the bannana peel method more because you can get it accurately and fully enganged, and then you seal the cable sheath back over after you're done. In most ARMY and Telco installations, this is how it's done. But to each his own...
And rather than using your "trusty" electrical tape on the post wrap job, I'd reccomend an electrical PVC tape. I can't remember what the brand name is, but there are a few brands that will provide outstanding weather protection, and they'll also stick through any icky pick or cable insulating gel.
Depending on how you're doing your splice, many different applications may be correct.
mikeydidit
IS-IT--Management
Something that I didn’t see mentioned is that I would install a PE type cable. It has the metal sheath that you will need to ground and bond your cable and a jelly type material inside to protect your cabling from moisture. I live in Louisiana and if it’s in the ground here, it will get wet. Even in conduit. One more thing I would like to add. I started in telecomm about 16 years ago. Apparently someone did not do their homework on grounding and bonding. I had an old Dimension 2000 that had taken a lightening hit. If you like overtime, and a lot of sleepless nights. Don’t protect that cable. That will do it. When I did get a new switch I run some #6 to a corner of the building and drove a 6’ grounding rod in, as well as the building grounds that I had. May have been an over kill but I have not taken a hit on this system.
If you find any mistakes, please consider that they are there for a purpose. And everyone needs a purpose.
Mikey
If you find any mistakes, please consider that they are there for a purpose. And everyone needs a purpose.
Mikey
- Thread starter
- #12
daronwilson
Vendor
Perhaps I misread your instructions, but it sounded like you wanted to cut the cable in six locations for about 2". I added those six cuts up and thought that was an awful lot of cable to expose. Now if I understand you correctly, you want to do this around the circumference of the wire. Perhaps we are talking different types of grounding attachments. We normally use a 2 piece clamp with a stud attached to it. A hole is made in the shield and the stud pushed through from the inside, then the teeth of the clamp bite into the shield from the inside. Once you get a hole and get that stud pushed through there, I see no other benefit to disturbing the shield anywhere else. I'll look up which part we use and try to get some photos, maybe that makes sense. Certainly there are many ways to complete the task. My experience with OSP cable like this is from sitting on a splicers box in the hole putting it together. I've learned from many telco guys, it may not be the best method, but it is widely used and solid.
Yes, PE-89 or PE-39 cable should do fine.
I'm not sure I understand your take on protectors, maybe you can explain that a bit more. I think the ones we get in loaded building terminals are 240V modules. We replace those with a lower voltage (75v) module when we send digital sets out there since the digital set is generally at 24 or 48 volts and does not carry a 90-100 volt ring voltage. What are you seeing for digital sets that won't work on a 240V protector?
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
Yes, PE-89 or PE-39 cable should do fine.
I'm not sure I understand your take on protectors, maybe you can explain that a bit more. I think the ones we get in loaded building terminals are 240V modules. We replace those with a lower voltage (75v) module when we send digital sets out there since the digital set is generally at 24 or 48 volts and does not carry a 90-100 volt ring voltage. What are you seeing for digital sets that won't work on a 240V protector?
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
AvayaNovice
Vendor
It's not the voltage actually going through the protector that's the problem. Obviously to comply with low voltage licensing and what not, you're never going to get near 240V. I kind of explained that improperly, I meant that the telco protectors sometimes do screwy things with signal transmission... as to why that happens, I'm not sure.
As far as the grounding strap...
We use what looks like an ohm icon almost. You bananna peel strip the cable in six places, get that strap around it and clamp it shut at the bottom, and then you run the jacket back over the strap to where the jacket ended previously, and tape it off.
I'll have to take a picture of one of our splices to better explain it. This is more of the ARMY way of doing it, although all of SBC's underground installations that I've seen are like this too.
My experience is from splicing underground and aerially... although I haven't been doing it very long. I've seen quite a bit though in my day becausae our infastructure here is a huge army base, so many different things going on.
Bottom line, for PBX or phone switch type installations, I'd go with the Avaya protectors. They're small, they work well, and they're easy to install.
And indeed... I'm here to learn as well.
As far as the grounding strap...
We use what looks like an ohm icon almost. You bananna peel strip the cable in six places, get that strap around it and clamp it shut at the bottom, and then you run the jacket back over the strap to where the jacket ended previously, and tape it off.
I'll have to take a picture of one of our splices to better explain it. This is more of the ARMY way of doing it, although all of SBC's underground installations that I've seen are like this too.
My experience is from splicing underground and aerially... although I haven't been doing it very long. I've seen quite a bit though in my day becausae our infastructure here is a huge army base, so many different things going on.
Bottom line, for PBX or phone switch type installations, I'd go with the Avaya protectors. They're small, they work well, and they're easy to install.
And indeed... I'm here to learn as well.
daronwilson
Vendor
Well a picture would help, perhaps if you give us the brand and/or model of what you are using we could find it online and check it out. The ground clamps we use are 3M I believe, I'll look tomorrow and try to get you a reference so it makes more sense too.
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com
Ive found that bonding both ends is a must, as well as protectors on both ends...
I have had success in my broadcast days with carefully cutting the insulation off, leaving the bare foil shield, then wrapping it with a braid, held tight with a cable clamp, then cover it with tape. NOT the prettiest thing, but it worked. I would never do it outside, the ground braid acts like a wick and sucks up water! Inside in dry locations, it worked....
As for protectors, I use alot of the PICO type, and plug onto a 66 block really nice. Ive also used the Polyphaser stuff, all good, just the PICO is easier and neater for a full 66 block.
Its my experience the most expensive and important equipment always attracts the lightning......leaving the cheap stuff alone....
Randy
I have had success in my broadcast days with carefully cutting the insulation off, leaving the bare foil shield, then wrapping it with a braid, held tight with a cable clamp, then cover it with tape. NOT the prettiest thing, but it worked. I would never do it outside, the ground braid acts like a wick and sucks up water! Inside in dry locations, it worked....
As for protectors, I use alot of the PICO type, and plug onto a 66 block really nice. Ive also used the Polyphaser stuff, all good, just the PICO is easier and neater for a full 66 block.
Its my experience the most expensive and important equipment always attracts the lightning......leaving the cheap stuff alone....
Randy
- Status
Similar threads
- Locked
- Question