POTS Line Amperage

[adit1]

I have 4 POTS lines coming into a building. Measuring with my digital buttset I get 51V on all 4, 30ma on line 1, and 50ma on 2,3, and 4.

The measurements were made at the Demarc with inside wire disconnected.

Should all 4 amperage measurements be the same? Are the ma measuments within spec?

Before the breakout there is a Western Electric splice (?). The building was built in the 40's, and assume the cable was dropped in maybe during the 60's or 70's.

The reason I ask is because we keep losing Line1 on the CID Line Card of a CICS. This is the 3rd card that lost Line1 since August. I searched around the net and couldn't find anything on bad card runs failing lines.

Thanks!!!

 

[GHTROUT]

If it were me, I'd report it to Telco - give a good description of "a problem" that will force them to actually do work... such as "you hear other conversations alot" or "the line doesn't ring when it rains" or you could just tell them the truth I guess.

~~~
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[pbxn]

GH is right, and even if you use the good suggestions of a "problem" you may have to demand dispatch. Don't be alarmed when they tell you charges may apply if it is isolated to your iw, that is standard op proceedure for their first line dispatchers.
Fluctuations in voltage can mean a cross in the outside plant.

 

[adit1]

VZ came out, I was not there. The VZ tech came out and said all was OK. All lines tested out to 50ma.

I think he was full of BS and told the customer what he wanted to hear.

I plan to go back out there later this week to take measurements again.

When I measured last week it was 30ma on several tests over a few hour period.

It's not the inside wire, as I was testing at the demarc with all IW disconnected.

Thanks for the comments!!!

 

[crumthwacket]

Hmmm... 50ma sounds hot. I'm inclined to think your readings should be between 25ma and 30ma. It's definitely a telco problem; make sure your on site when the tech arrives to prove it to him.

 

[skip555]

nothing wrong with 50ma from the telco perspective , I believe there upper limit is something like 125ma

80 - 90 is not unusual around here

use some regulators to bring it down to 25

 

[allisland]

Are you terminating a call from the demarc through you MA meter? ( meter in series with butt set)if so bare minimum has to be 16MA (if my old memory is correct)so 20 to 30 would be good to hold up CO equipt, and on a non terminated line straight across the demarc 50 is about right.

 

[skip555]

Are you terminating a call from the demarc through you MA meter? ( meter in series with butt set)if so bare minimum has to be 16MA (if my old memory is correct)so 20 to 30 would be good to hold up CO equipt, and on a non terminated line straight across the demarc 50 is about right.

your thinking of DC voltage in which case your right 50vdc is about right for a on hook condtion

MA min is I believe 23ma , ideal is 23 -30 anything above or below can be problematic

16ma is very low and you can get the telco to bring it up in that case

I believe they have to supply 23ma min but max is around 125ma

50ma is high and can cause issues but the telco isn't going to do anything for you , you need to address it yourself

(I'm not sure how the OP is measuring but my Harris ts25d displays both line voltage and MA on the display in the corner )

 

[adit1]

Testing w/

http://www.jdsu.com/products/communications-test-measurement/products/a-z-product-list/lb-pro.html

Should be 5-15ma Off-Hook

 

[skip555]

Should be 5-15ma Off-Hook

5-15 VDC off hook yes 5-15MA way to low

 

[adit1]

yes, typo.

 

[allisland]

No I was referring to milli amps not volts, and the 16Ma I was referring to was what was needed to active and hold up CO relays on a terminated call, anything less and they would drop, so 16 Ma was bare minimum on the verge of not working!
Anything above 20 should be fine.
And I keep saying terminated call, where your measuring Ma while CO equipt is up, not in an idle state across the pair.

 

[adit1]

Idle, the test sets can't measure amperagewhile off hook, only voltage.

I have 3 lines at 50ma idle, and 1 at 30ma. The one at 30ma keeps blowing its line on the line card.

I'm more concerned about the difference in amps between the lines rather than the actual measurement. In other words, where are the other 20ma being drawn off. I'm about 4.5 line miles from the CO.

I moved up lines (last time) 1,2,3 to 2,3,4 on the line card and line 2 eventually blew. This is how I know this is something on line 1. (Been through a few cards).

 

[skip555]

I'm more concerned about the difference in amps between the lines rather than the actual measurement. In other words, where are the other 20ma being drawn off. I'm about 4.5 line miles from the CO.

I moved up lines (last time) 1,2,3 to 2,3,4 on the line card and line 2 eventually blew. This is how I know this is something on line 1.

your looking at it wrong

50 is to high and not a norm

30 is about right

you don't have "20ma being drawn off "

the problem doesn't seem to be loop current related , you need to look at the primary and secondary protection and the grounding on the 30ma line

in addition to the protection I would install regulators and bring all lines down to 25MA

 

[macphoneguy]

I would have to agree with skip555, 20-30 ma is the "norm" anything higher and whatever is connected to it can intermently Go bad, hung up anything between 48 & 52 volts DC, off hook 5-15 volts is normal for regular loop start lines I would hightly recommend getting a loop current regulator to bring them down, from a outfit like sandman.com the Carrier may or may not do anything about it

 

[jerryreeve]

Mike sandman has some very good tutorials on loop current and other analog testing you can do

http://www.sandman.com/loop.html

and about 1 or 2 pages down the screen there is a list of bulletens for troubleshooting.

----------------------------
Hill?? What hill??
I didn't see any $%@#(*$ Hill!!
----------------------------
JerryReeve
Communication Systems Int'l
com-sys.com

 

[LkEErie]

I think most of you better review Ohms law. Idle voltage in telco is 48-52 volts and there is a tolerance. Loop current, measured with a telephone and meter set to mA in series is probably good between 20-32. Anything higher will kill CID detection equipment (I know that for a fact) and at 125 mA there better be some sort of loop extender on premise because you just wired to the wrong end of it.

We have good success (and competitive pricing) with the ITC-4001.

http://www.independenttech.com/ITC-4001.htm

LkEErie

 

[skip555]

Ive used the one with dip switch's but I like the Regulator Mike sells it will put out 25ma even if the loop current changes

with the dip switch's if the current form the telco changes you need to reset it

 

[rconn]

Hi,

I have had many problems like the one outlined with Norstars and line cards.

1)There was a problem with certain versions of CLID cards. They did not even like 30 ma for long. I believe the newer cards are more durable but don't quote me. The older CLID cards (they were raised from the surface when mounted) are certainly better cards and I have had much success with these cards.

2) The reason (I believe) line one is burning out even with higher line currents on the other lines, is that more calls are handled on line one so it is off-hook more often and for longer periods.

3) My most common solution is to put resistors in line prior to the Norstar. Start with 100 ohm 1/4 watt and move to 300 ohm until the current is somewhere near 25 ma. I have never replaced a card again after putting in the resistors (a few customers had been through many cards). You need to put one resistor in line on both the Tip & Ring to keep it balanced.

I test with a pair check meter and the telco test circuits. Any terminated call will work.

It has worked for me.

Rob