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JTRockville
Data Ho
Premium Member
join:2002-01-28
Rockville, MD

JTRockville to GRIZZMEISTER

Premium Member

to GRIZZMEISTER

Re: FIOS Installation is a go in Montgomery County

Wow, is that possible? Can the ONT be powered with the copper line?

I realize a lot of folks wouldn't want/need it - look at how many folks have already ditched copper altogether. But I'd pay extra for it!

GRIZZMEISTER
join:2005-02-10
Wake Forest, NC

GRIZZMEISTER

Member

said by JTRockville:

Wow, is that possible? Can the ONT be powered with the copper line?
I'm not sure but I used to design T-1 lines and the mid-span repeaters used for those were CO powered. Granted they only needed 48V DC. What type of power requirements do the ONT's have? By that I mean, what is the standard power rectified to? Man... I really need to check out the Fios setup for myself as I have so many questions. I'd probably just spend all my time playing XBOX-LIVE games with it though.;)

nycdave
MVM
join:1999-11-16
Melville, NY

nycdave to JTRockville

MVM

to JTRockville
Nope. The ONT requires way too much more power than a POTS line can provide. Anyway, the whole point of FTTP is to move away from the copper-based OSP. The copper maintenance costs are very high today trying to provide basic dial tone and DSL - forget about trying to redesign the OSP to provide backup power.

So FTTP and copper for power backup isn't the plan.
BarneyBadAss
Badasses Fight For Freedom
Premium Member
join:2004-05-07
00001

BarneyBadAss to JTRockville

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to JTRockville
JT,

Just get another provider on your copper; like MCI / AT&T / SBC or another carrier besides VZ on your copper.

They will be hard pressed by Federal Law to "Disconnect" another carriers service.
Robert Morrisson
join:2000-03-31
Silver Spring, MD

Robert Morrisson to nycdave

Member

to nycdave
It is not a case of the ONT requiring too much power. It is a case of a cable that moves light, not electricity.

The fiber transmits light from the central office to the ONT at your home. It also transmits light from the ONT to the central office. That is all it is - light.

This light is generated by powered equipment at each end of the fiber. That means that the central office and your ONT must have power to product this light. Once the fiber is lit it can stretch for many miles.

This is quite unlike copper, on which the signal strength diminishes rapidly over distance. That is why DSL does not work when the line is more than 15,000 feet long.

The bundler of fiber does not contain any copper, except possibly to provide a signal path for sniffing out buried lines.

The signal over a copper cable drops with the length of the line, which is one reason a DSL connection is limited to 15,000 or so feet. If you did mix copper and fiber in the same bundle you certainly could not provide enough power to operate one ONT, let alone every ONT on the line.

So, if you want the benefits of fiber you will have to suffer the risk of losing the service after 4-8 hours. You could buy an add-on battery pack from Verizon and modify it to run from a deep-charge marine battery. Or you could run the battery backup unit from a large UPS.

sdgthy
@optonline.net

sdgthy

Anon

While the point about the fiber only carrying light, I agree with. Fiber can't transfer power without great loss. I might have to question the "too much power" comment.

From various pictures of the BBU, the battery is 7.2AH, that means a good battery should be capable of 7.2 amps for an hour, or 1 amp for 7.2 hours. Another comment where the BBU P/S was miswired suggested it lasted about 8 hours before killing the battery. That would seem to indicate that the ONT draws a bit under an amp (anyone who already had an install and has an ammeter, feel free to enlighten me).

Hmm, I just thought of something, now I have to ask a question in that thread...

The POTS system was designed to supply no more than a few mA, the ring current being the greatest demand. That's why there's RE numbers. In fact, for those who remember them, Princess phones used to require an independent AC line transformer for it's lamps and used the second pair of CAT3 for that. The Trimline introduced LED's.
Robert Morrisson
join:2000-03-31
Silver Spring, MD

Robert Morrisson

Member

Fiber cannot carry any current. It only passes a beam of light generated at one end of the fiber to a photo-sensitive transistor at the other end of the fiber.

The transmitters and receivers at each end require power. A battery rated at 12 volts and 7.2 amp hours would furnish around .6 amperes. The load from 32 ONTs would be 19.2 amps, for just one local cable.

that kind of current would require a #12 cable for a very short run or a #8 or #10 cable for a long run (standard household wiring is #14).

If you went to a higher voltage such as 110 volts the load would reduced to 2 amps, requiring a much smaller wire. The problem is, you would need to house the power conversion equipment somewhere.

That 2 amps would only supply 32 ONTs. One trunk from the central office can handle far more ONTs than that so that wire would have to be huge.

An alternative would be to drop power from a power company pole. That is just duplicating the problem, while keeping it out of your control.

It is a fact of life that fiber to the door requires local power at both ends of the fiber.

sdgthy
@optonline.net

sdgthy

Anon

That didn't come out quite right.

A photodiode generates current from light, so it is possible to transfer power. In fact most any modern switching power supply uses this. Applied current bias to reduce noise is a whole 'nother subject. The problem is that the apparent power required by the ONT would not be practical to transfer over fiber.
Robert Morrisson
join:2000-03-31
Silver Spring, MD

Robert Morrisson

Member

Well, close.

A transistor passes a large current from its emitter to its collector when a small voltage (bias) is impressed between its base and emitter.

A photo-transistor has a photo-sensitive diode as its base element. Light shining on the diode generates a voltage that causes the transistor to conduct, thus switching the power between the emitter and the collector.

The power source for the light does not pass through the fiber. That power generates light, which controls the photo-transistor on the other end of the fiber. The power for the photo-transistor must be supplied locally.

You cannot put voltage on the fiber and draw current through it. So, while the power source at the central office does control the photo-transistor at your home, that current does not pass through the fiber.

So, there is no current passed down the fiber. For current to flow you need a path for electrons. Glass fiber, being an insulator, does not provide such a path. So, if you take a lightning strike on the fiber bundle feeding your house your ONT will not be affected.

Well, it might be affected if the fiber melts or breaks, but that is another story. At least the photo-diodes / opto-isolators will have done their job.
Photo-transistors are often used in a device called an opto-isolator, which is designed to isolate two power sources. A voltage from one signal source feeds an LED, which is intimiately coupled to the base of a photo-transistor. Light from the LED causes the transistor to switch on and off in response to the voltage on the LED. The two power sources are totally isolated; a high voltage surge will not cross the opto-isolator.

vzguy
@verizon.net

vzguy to JTRockville

Anon

to JTRockville
im sure its possible (as long as a conductor that small can handle enough power to do that) but i work for vz and i dont ever see that happening. buy yourself a generator people, judging from the size and price of the houses of where weve been installing this stuff, no doubt you can afford one.
vzguy

vzguy to nycdave

Anon

to nycdave
i disagree, again its possible. i know for fact a vz tech was killed in a co a few years ago by power backfed on a pots line while working on the frame. personally i think its too dangerous and highly unlikely. as i said before i work for vz, i havent heard any discussion of this. i believe the idea is to completely jettison copper once the penetration of fios gets to a certain point.

JTRockville
Data Ho
Premium Member
join:2002-01-28
Rockville, MD

JTRockville to BarneyBadAss

Premium Member

to BarneyBadAss
said by BarneyBadAss:

JT,

Just get another provider on your copper; like MCI / AT&T / SBC or another carrier besides VZ on your copper.

They will be hard pressed by Federal Law to "Disconnect" another carriers service.
It just occured to me - I already have another provider's service: MidAtlanticBroadband T-1. The T-1 uses a separate NID, but it has a connection to my VZ POTS NID.

VZ won't touch the T-1 NID during a FiOS install, will they?

If VZ tries to replace the POTS NID for FiOS, what will happen to my T-1?