Multi - meter

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If the plans call for 470 ohm and you have 24k, then either the plans are wrong or you have the wrong resistors.
I do not know a lot about alarms, etc., but for an EOL resistor 24k seems too high a value, while 470 ohm seems low.
If the line signalling voltage is 12V, then 470 ohms would dissipate about 1/3 watt, which is too much for a 1/4 watt resistor.
 
Fulthrotl said:
old style fire alarm systems with fusible links on duct dampers
need to be tested with extreme caution with older meters.

i watched a guy drop 60 zones in a hospital with a simpson analog once a long time ago.

the voltage across the meter from the internal battery when measuring ohms is
enough to trigger the fusible link.
Click to expand...

There must be more to the story.

I find it unlikely that the current used by a Simpson to read ohms is melting a Fusible link.
 
git2work said:
I have an EOL ( end of line device) that is a 24k resistor according to the color code. Left to right I have red, then yellow, then orange . Then a big space then silver.red is 2,yellow is 4.orange is the multiplier so 24k is my resistor.the silver band means it has a 5% tolerance. My question. Is this: the plan says "end of line device: 470ohm,1/4W resistor, p/n 140-820164. The resistors that were supplied are the 24k resistor. Why? Is 24k = 1/4W?
I guess I need to study ohms law some more. If anyone has any thoughts on this I'm all ears.

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What make and model fire panel?

Which fire circuit is it, horns or pulls?
 
Siemens is the equipment. Horn strobes are the circuit. NAC panels are called pad - 3's. I haven't seen the panel that controls the NAC panels yet. Literally this is the first fire alarm system of any type I've been involved with so I promise you I know very little if anything about how it works. Plan says put the mentioned resistors at the EOL. I've done that and when I test at the NAC panels I'm getting the reading I should get. 24k . I'm using 24k resistors. Just don't know why the plan calls for 470ohm 1/4 watt resistors? I'm thinking the fire alarm company who is drawing this stuff up is cutting and pasting info that is general into the legend on the plan.

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470Ω is not unusual for a EOL device on a conventional panel. 24KΩ makes me think it's for device on a addressable loop. The higher resistance for addressable devices lowers per device current and reduces the overall current required by the SLC.

Conventional – 24V / 470Ω = 0.05A
Addressable – 32V / 24000Ω = 0.0012A
 
I'll get back to you on that later today. I'm at a different job this morning. I appreciate the input.

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Can a person use 1/2" flex for fire alarm wiring? Someone is telling me that only 3/4" can be used.

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iwire said:
Yes, because non of us field guys would every ignore the safety rules and do things how we have always done them.:angel:

As much as we enjoy vilifying the 'safety guy' more often then not we can blame our own actions for these one size fits all rules.
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There are two sides to every issue. I remember a "safety guy" standing under a loaded trackhoe bucket, (he did have a hard hat on), counselling a couple guys because they were in a 3 foot ditch without a ladder.
 
git2work said:
I need a ohm meter capable of reading resistance that is found amongst fire alarm panels. one of our line voltage guys was spouting off about how is meter was the best. It was a fluke. Turns out that line voltage meters don't read resistance high enough. Any suggestions on a meter that works at higher ohms?

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Wow, talk about a thread getting off topic...

To answer your question, your options are wide open
. In the old days, we had voltage testers, most often a "Wiggy" that we carried in our pouches at all times to check for voltage. Mostly because they were not bulky. When you needed to troubleshoot, or check small DC voltages etc. You went and got your Triplett shown, or a Simpson, 260, if you were serious, or some half butt Radio Shack multimeter if you were on a budget. Then came, proximity "pen" testers, and a couple companies also started creating voltage testers that had both proximity sensing and/or continuity along with the voltage testing. Throw in also that in this same time frame, meters, both voltage and continuity were evolving, (or devolving if you wish) from analog (meter needle display) to digital. Nowadays it is common for a field electrician to carry a compact meter that that displays accurate voltage, amperage and resistance, but the versatility of each is limited to the desires of the person.


So, you can get a single meter to do a bunch of things or you can get different meters to do different things. If all you are looking for is a meter to read end of the line resistors, open, short, and ground fault, you can pick up a 10 dollar analog meter at Harbor Freight or Home Depot. I would not use the same on a live circuit, even though they have that function! But it will serve just fine for resistance troubleshooting.

I have a Fluke 117 that is digital and has the functions you are looking for, but I wouldn't carry it on day to day electrician stuff. I love my old Simpson 260 when I am trouble shooting real industrial style voltage. I would prefer my Fluke when I am doing newer PLC type troubleshooting. And then I always have to consider, CT's and how I am going to read both DC and AC current.

Bottom line, don't necessarily try to get one size fits all. There wouldn't be thousands of options out there for various combinations of electrical testing features if the demand wasn't there.
 
git2work said:
I have an EOL ( end of line device) that is a 24k resistor according to the color code. Left to right I have red, then yellow, then orange . Then a big space then silver.red is 2,yellow is 4.orange is the multiplier so 24k is my resistor.the silver band means it has a 5% tolerance. My question. Is this: the plan says "end of line device: 470ohm,1/4W resistor, p/n 140-820164. The resistors that were supplied are the 24k resistor. Why? Is 24k = 1/4W?
I guess I need to study ohms law some more. If anyone has any thoughts on this I'm all ears.

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Click to expand...

You have mixed the resistors supplied for the Siemens HTRI-S/D/R module with the ones for the ZIC-4A/ZIC-8B/PAD-3/4.
 
git2work said:
Can a person use 1/2" flex for fire alarm wiring? Someone is telling me that only 3/4" can be used.

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Click to expand...

Flex is fine, unless the specs or local requirements say otherwise.
 
git2work said:
Siemens is the equipment. Horn strobes are the circuit. NAC panels are called pad - 3's. I haven't seen the panel that controls the NAC panels yet. Literally this is the first fire alarm system of any type I've been involved with so I promise you I know very little if anything about how it works. Plan says put the mentioned resistors at the EOL. I've done that and when I test at the NAC panels I'm getting the reading I should get. 24k . I'm using 24k resistors. Just don't know why the plan calls for 470ohm 1/4 watt resistors? I'm thinking the fire alarm company who is drawing this stuff up is cutting and pasting info that is general into the legend on the plan.

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Use the 24K resistors.

The main panel could be an MXL/V, XLS/V, CerberusPRO, or even an ancient System 3.

I speculate you are correct regarding cutting and pasting on the drawing. It is also possible that the PAD-3 is being triggered by a TRI-R or an HTRI-R, in which case they may be using the monitoring input on the device to send a trouble status back to the MXL/V or XLS/V. Then the 470 ohm resistor goes across the trouble contact on the PAD-3.
 
Multi meter

Multi meter

You need a high resistance ohm meter which is usually called Meggar to measur high resistances. Fluke company also makes high resistance
insulation tester which measure high resistances. You can try that.

​
 
Shaun marsh said:
You need a high resistance ohm meter which is usually called Meggar to measur high resistances. Fluke company also makes high resistance
insulation tester which measure high resistances. You can try that.

​
Click to expand...
The difference between a good quality multimeter and a "megger" is the multimeter uses just a few volts (generally whatever the batter powering the meter is) for a test signal voltage, where a megger uses a high voltage. Most meggers have select-ability of test voltage as well usually have a low volt setting that is same thing as a multimeter then going up to 100, 250, 500 and 1000 DVC for test voltages.

The OP's application was for items that are supposed to measure in the kilo-ohm ranges - most multimeters can read those ranges fairly reliably, and many can read into the low meg-ohm ranges as well. The megger is really more for insulation testing then general resistance readings.
 
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