Multi - meter

[git2work]

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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[luckylerado]

Hands down Triplett 310

 

[Barbqranch]

Wow, I haven't seen one of those Triplet meters in 40 + years. My dad used to have one, not as pretty and sharp looking, though.

Different Fluke meters have different resistance scales. We have a clamp on ammeter that measures up to 40 k ohms, while my 117 measures to 6 M ohms.

 

[GrayHair]

For an analog meter I would recommend one with a resolution/sensitivity of at least 20,000 ohms per volt. This refers to the meter movement; i.e. If the meter is set to 1 Volt, the resistance of the movement is 20K Ohms. As the voltage setting is increased, the movement resistance increases in proportion.

Digital meters typically have a sensitivity of 10Meg Ohms or greater on all settings, making them more accurate.

 

[luckylerado]

For fire alarm troubleshooting it is less about the ohm range on the meter and more about the voltage of the test battery.

Look for a meter with a 12V test battery and you will be amazed how well you find grounds faults that are invisible to your typical multi meter.

 

[iwire]

Hands down Triplett 310

View attachment 13787

Not CAT III rated, that can't be used for those of us under safety programs.

 

[luckylerado]

Not CAT III rated, that can't be used for those of us under safety programs.

On a 48V system?? I work under EM-385 and have never had a problem. It is really a specialty meter IMO and I would not pull it out for much other than FA troubleshooting.

 

[GrayHair]

Some facilities will not allow test equipment below a certain rating on their premises.

Not long before I retired, I arrived at a service call and was directed to the Safety Dept where I expected to be checked for steel-toed footwear, etc. What they wanted was to see all the electrical test equipment I was taking in and wouldn't let my old "just-in-case" analog back-up meter in because it wasn't CAT III. They wouldn't let me leave the meter in the van; had to leave it in their office and pick it up on my way out. They even waffled on my butt-set, but did let it through. At one or two other places I had to agree not to use a meter that wasn't CAT III.

 

[git2work]

I've read that the voltage output of the meter is of particular concern due to the fact the fire panel reads resistance based on more volts than a 9 volt meter produces. What amount of voltage does a Triplett provide? I was told a Klein MM 100 or 1000 was good for fire alarm but after reading everyone's comments I'm rethinking my choice.


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[luckylerado]

...What amount of voltage does a Triplett provide?...

It has both a 1.5V and 12V battery. It bums me out to learn that it may not pass muster with some safety departments. As long as you are using it IAW the instructions and on systems within its rating it seems silly to tell a tech that he cannot use it within its intended design. Triplett has been making test equipment for over 100 years.

 

[kwired]

It has both a 1.5V and 12V battery. It bums me out to learn that it may not pass muster with some safety departments. As long as you are using it IAW the instructions and on systems within its rating it seems silly to tell a tech that he cannot use it within its intended design. Triplett has been making test equipment for over 100 years.

View attachment 13791

Some department heads or safety officers just don't want to take the chance of a technician actually knowing what he is doing:happyyes:

There is nothing wrong with using it if used on low level power circuits below it's max rating.

Chances are the safety officer doesn't even know exactly what this is all about - just knows they want CAT III equipment and if yours isn't it is not allowed.

 

[iwire]

Some department heads or safety officers just don't want to take the chance of a technician actually knowing what he is doing:happyyes:

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.

 

[GrayHair]

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.

Amen!

 

[kwired]

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.

Not saying all safety guys are right or wrong, but get into a plant with many other hazards present, if the safety guy knows little about electricity, rules for electrical safety will be same for plant maintenance and electricians as it is for the office staff.

Bottom line is the tool in question is still safe if used within it's limitations - and a true qualified person will know what those limitations are, the safety guy may not be qualified to know this though and doesn't fully understand.

Now that said OP, appears to be working on limited power systems - that could possibly be a game changer over someone that works on those plus non limited power systems.

 

[meternerd]

Why can't you use a megger? Most have ranges starting at 100V. Shouldn't harm a low voltage fire alarm system. I worked the 48V fire alarm system at a nuclear plant during initial startup and that's what we used.

 

[GrayHair]

Not saying all safety guys are right or wrong, but get into a plant with many other hazards present, if the safety guy knows little about electricity, rules for electrical safety will be same for plant maintenance and electricians as it is for the office staff. ...

I guess they had an incident that brought on new rules or enforcement of existing rules. Maybe the incident was at another plant.

The call was for a Comm Fail to the central station so response was required (UL fire account). 9 times out of 10 the signal was missed somehow and I just made the panel communicate to central station.

 

[Fulthrotl]

For fire alarm troubleshooting it is less about the ohm range on the meter and more about the voltage of the test battery.

Look for a meter with a 12V test battery and you will be amazed how well you find grounds faults that are invisible to your typical multi meter.

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.

 

[GoldDigger]

More to the point the current from the Simpson on the lowest resistance range was enough to trigger the fusible links.
The issue is the size of the series resistor used to limit the test current, not the supply voltage of the test circuit.
I recall having a meter that used one or two D cells to allow a high current low ohm range.
The resistance reading at mid scale is essentially the series resistance value for that range.

 

[git2work]

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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[gar]

151116-2012 EST

git2work:

A 1/4 W or a 10 W or a 5000 W resistor defines how much power the physical size of the resistor can dissipate and provide long time reliable operation.

If I apply 120 V to a 100 ohm 1/4 W resistor it will pop like a fuse. For a short time this is 144 W being dissipated in the minute little 1/4 W resistor.

Roughly I need a resistor with 500 times the surface area of the 1/4 W resistor to dissipate this amount of power on a steady state basis. It is probably save to say that the 1/4 W resistor could dissipate without much damage this amount of power for 1 microsecond.

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