electrical opinion

[JOB]

I am putting a couple of electrical temperature sensors into supply and return pipes. The manufacture of the sensors rec omen 18 AWG stranded wire. On Amazon I found 18 AWG with 34 strands and another with 150 strands, both with tinned copper wire. The 150 strand wire was high temp. 200* C. The outside appearance looked the same, color of the insulation. Would it really matter which wire was used. The 35 strand wire was rated for 12 volts DC, I am using it for 24 Volts AC. 18 AWG is thermostat, or door bell wire which is usually a solid wire. any thought or suggestions?

 

[Bob]

Since you are (presumably) not dealing with extremely high frequencies ANY number of strands should work.

The wire with the high strand count will likely withstand continuous flexing the best, but that probably sin't an issue, either?

 

[David G]

Agree, either should be fine, the more strands the better it handles flexing, but any strands are better than solid.

 

[Mule Meat]

Electrical current does not travel through wire, but rather along the outside if it.

More wires equal less resistance. Less resistance equals higher voltage and a higher heat range.

With your choice either will work just fine. The 34 strand will be easier to make a good connection. 150 strand will have very thin wire (thinner than a human hair) and the insulation would have to be removed very carefully in order to keep from breaking a lot of strands removing it.

 

[circus]

When in doubt, overkill. Heavier wire with higher voltage rating than nominal.

 

[Dusty MI]

Because you are using 24 volt AC, I would not use the 12 volt DC wire.

Dusty

 

[Fred Werring]

Maybe buy a 16ga extension cord and cut the ends off?

It's a heavier gauge wire, insulation is rated for at least 120v, would give you a spare wire if needed (assuming you only need 2 wires for the sensors) and may be cheaper than buying wire.

FWIW

Fred

 

[JOB]

I was sort of wondering what that application would be for more or less strand's or if there is different applications. Other than more strand's make the wire more flexible. I am kind leaning towards the 150 strand wire I am thinking about putting a dab of solder on the end of the wire where it is connected. The wire that is connected to the sensor wire I might use a wire nut the other end I need to push it into a tight connector so I will need to use something to stiffen up the wire so that wire I will put the dab of solder on.

 

[JOB]

My runs are about 40 feet. That 24 volt ac transformer is used on my hot water boiler and 18 wire is used to go to the TT terminals at the boiler control. I am using a separate transformer for the Hot water temperature sensors. The sensors require two wires each and I need two more wires to get the 24 volts to the Liquid crystal display.
Thanks for the offer on wire, I have some wire and will get other wire if required.

 

[JOB]

The maker of this Digital temperature gauge recommended stranded wire to get a reliable reading. The wires will be fastened to the wall so there will not be any flexing.

 

[JOB]

Yes Bob the wires will be connected and then fastened to the wall. I wish I could bury them in the wall but this is a re-do after 30 years of a different heating design. So no flexing of the wires.

 

[Brokenboltz]

Blah blah blah. Voltage is pressure. Voltage does not make heat. Current makes heat, amps. If your worried about voltage drop use a 14 awg THHN available at Lowes. Solid wire of the same gage is smaller then stranded. Stranded is made to be more flexible- period.

 

[Dusty MI]

Wire is measured by size, makes no difference how many strands as far as capacity.
American Wire Gauge/AWG

Dusty

 

[JOB]

Not worried about heat generated from voltage, The wire will be 18" from a 300* or maybe 400* flue pipe The sensors will be 12" or so from the flue pipe at hottest point of the flue pipe. This little device does not draw a lot of electricity 14 awg wire is way over kill.

 

[JOB]

The seller of that 18 AWG wire that said is was rated for 12 Volts was promoting it for automotive use. The seller of the other 18 AWG wire just stated what the wire
would carry. !2 volts DC or 24 Volts AC should not matter. This little device will not consume a lot of electricity.

 

[Texasmark1]

It does flow through the entire conductor at dc and lower freqauencies. As frequencies increase it prefers the path of least resistance which is
the surface. By the time you get to microwaves, it is oscillating so fast that you can control it with air conditioning ducts for the least amount of
attenuation.

Multi stranded wires are made for flexing. What flexes more than a welding cable" Check out 0 or 00 welding cable's strands cxapable of
carrying a couple hundred amps and the same solid copper 00, capable of the same couple hundred amps that is feeding power to your house.

60 Hz AC-DC {Mox-Nix). Most anything will carry door bell current 40 feet. At those voltages, most any insulation will carry the voltage which
is isolated from house power, via the 24V stepdown transformer, and the source is high impedance meaning you aren't going to get much bite if
you get across it. If running DC it's batteries or a DC power supply fed off such isolation transformer. DC makes no sense unless it's from a
battery or an internal rectifier/power converter in the using equipment.

Reference for one: Mc Graw-Hill, Electrical Engineering Handbook!

 

[Texasmark1]

Amps per circular mil is the rating for either a 2% voltage drop like in power distribution to residential customers or heat rise in certain
applications where insulation temperature tolerance is a concern. A good general purpose number is a minimum of 400 circular mils per
continuous amp, (mil defined as 0.001").

In applications where weight is a serious concern, double or triple that load with specialty high temperature insulation requirements....aka
certain airborne devices.

 

[buickanddeere]

RTD’s or thermocouples ?

 

[tlock0331]

(quoted from post at 14:12:38 01/09/19) RTD’s or thermocouples ?

based on application and 2 wire, i would guess thermocouple

 

[JOB]

I did not recognize you comment as a question. I don't know what RTD’s or thermocouples are. Copy and paste this to your address bar, this is what I am installing.



https://www.azeltec.com/images/brochure.pdf

 

[buickanddeere]

(quoted from post at 05:40:20 01/10/19) I did not recognize you comment as a question. I don't know what RTD’s or thermocouples are. Copy and paste this to your address bar, this is what I am installing.



https://www.azeltec.com/images/brochure.pdf

A RTD varies it’s internal resistance linerally with temperature . They are shipped from the factory with dedicated lead wire . Loop the excess length up instead of cutting short and re-terminating.
Thermocouples are dissimilar metal in contact with each other . Heat will cause a difference in voltage and a small amount of current . Used in old time has burner safety controls . They are also the power conversion method on some space craft . To convert heat to electricity .
When extending the lead
on thermocouples . The wrong connections will bias the desired detection joint with the extension connection joints and bias results .

 

[JOB]

That is way over my head. If you pasted that web address in your address bar you saw what I am doing. I don't do things too complicated.

 

[buickanddeere]

(quoted from post at 17:59:00 01/10/19) That is way over my head. If you pasted that web address in your address bar you saw what I am doing. I don't do things too complicated.

I am on my phone and the link is not handy to cut and past . As tlock posted we didn’t even get into three wire thermocouples.

 

[tlock0331]

Is this it?

 

[buickanddeere]

(quoted from post at 17:59:00 01/10/19) That is way over my head. If you pasted that web address in your address bar you saw what I am doing. I don't do things too complicated.

If it is a 10K ohm thermistor/RTD. Even a couple hundred feet of #14 copper wire as extensions to reach the temperature indicator. The bias effect on the temperature won't be enough to notice in that application.
I am used to measuring processes that require a high degree of accuracy.

 

[David G]

A thermocouple should use the appropriate thermocouple wire.

A three wire RTD eliminates all wire drop issues.

 

[JOB]

Yes that is the sensor.