terrarium heat cable

[T-n-T]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it. It has a 110v plug at one end and is about 8 feet
long. The end has a small knob which I assume is a resistor of some
sort. The actual heating part of the cable is about four feet long, the
rest is just to get to the outlet. Oh yeah it is 15 watts. I think for
someone who knows how this works should be a no brainer. I recently saw
an article somewhere that suggested using a toaster or aquarium heater
element, halved , coiled around a small wire and threaded into a
silicone tube. Any advice would be excellent, thank you.

BTW, i have seen some online for planted aquariums that use a long
length of wire, which is exactly what I need but seems to be really
long.
http://www.thekrib.com/Plants/Tech/

 

[Genome]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it. It has a 110v plug at one end and is about 8 feet
long. The end has a small knob which I assume is a resistor of some
sort. The actual heating part of the cable is about four feet long, the
rest is just to get to the outlet. Oh yeah it is 15 watts. I think for
someone who knows how this works should be a no brainer. I recently saw
an article somewhere that suggested using a toaster or aquarium heater
element, halved , coiled around a small wire and threaded into a
silicone tube. Any advice would be excellent, thank you.

BTW, i have seen some online for planted aquariums that use a long
length of wire, which is exactly what I need but seems to be really
long.
http://www.thekrib.com/Plants/Tech/

Hmmmmmm, well.... I can't speak for others in this newsgroup but I think
we're all rather busy doing Night Rider lights with 555 timers for our 2CVs.
Things are quite competitive so a lot of this stuff is kept secret. I mean,
don't believe everything they tell you.... BASTARDS!!!!!

Cough....

Errrr, Anyway.

This sounds like one of those things that makes a difference between cute
things and soup so.... I mean, hey... play the nice guy and dole up the
money for a proper one.

DNA

 

[JeffM]

was: terrarium heat cable

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium.

http://groups.google.com/groups/sea...ipv_pPHz7ft1RIZ6HvvJW0y4Pue0pYgAOJQ&scoring=d

The last half of this thread explains why MULTI-POSTING is a BAD idea:
http://groups.google.com/group/sci....ups+*-*-*-*-two-groups-*-*-aren't-*-different

 

[default]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it. It has a 110v plug at one end and is about 8 feet
long. The end has a small knob which I assume is a resistor of some
sort. The actual heating part of the cable is about four feet long, the
rest is just to get to the outlet. Oh yeah it is 15 watts. I think for
someone who knows how this works should be a no brainer. I recently saw
an article somewhere that suggested using a toaster or aquarium heater
element, halved , coiled around a small wire and threaded into a
silicone tube. Any advice would be excellent, thank you.

BTW, i have seen some online for planted aquariums that use a long
length of wire, which is exactly what I need but seems to be really
long.
http://www.thekrib.com/Plants/Tech/

A lamp dimmer and an el-cheapo heating pad from a drug store (thing to
take out muscle pains about a foot square and water proof) - place
under the terrarium and on top of a sheet of Styrofoam if you want to
just heat the plants/reptiles. Low setting is about 25 (25-50-75)
watts so you'd need a lamp dimmer or wire a diode in series with the
120V and get 15 watts.

A tape for preventing pipes from freezing might also be adapted.

The idea of resistance wire and silicone tubing sounds dangerous, time
consuming and iffy at best. Aquarium heaters start at about 75 watts
and cost as much or more than heating pads.

 

[Homer J Simpson]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it.

How will you get it UL certified? Without that your home insurance is void.

Can you sit it over a 15 watt light bulb?


--
++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Required crap appended to avoid restrictions imposed by brain +
+ damaged idiots.
+
+ Server Response: '441 Posting Failed (Rejected by POST filter)', +
+ Port: 119, Secure(SSL): No, Server Error: 441,
+
+ Error Number: 0x800CCCA9
+
++++++++++++++++++++++++++++++++++++++++++++++++++++

 

[mkaras]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it. It has a 110v plug at one end and is about 8 feet
long. The end has a small knob which I assume is a resistor of some
sort. The actual heating part of the cable is about four feet long, the
rest is just to get to the outlet. Oh yeah it is 15 watts. I think for
someone who knows how this works should be a no brainer. I recently saw
an article somewhere that suggested using a toaster or aquarium heater
element, halved , coiled around a small wire and threaded into a
silicone tube. Any advice would be excellent, thank you.

BTW, i have seen some online for planted aquariums that use a long
length of wire, which is exactly what I need but seems to be really
long.
http://www.thekrib.com/Plants/Tech/

They make heat pads that are not too expensive that you could put into
the bottom of a terrarium. A seedling heat mat (made very similar to a
water bed heat mat) can be had in a 9x20 inch size for about 23 USD.
See link:

http://www.qcsupply.com/Products/474.aspx

There are also separate thermostats available for these to regulate the
average temperature.

- mkaras

 

[John Popelish]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it. It has a 110v plug at one end and is about 8 feet
long. The end has a small knob which I assume is a resistor of some
sort.

Maybe something more like a lamp dimmer.

The actual heating part of the cable is about four feet long, the
rest is just to get to the outlet. Oh yeah it is 15 watts.

Since the formula that relates voltage wattage and
resistance is W=V^2/R, 15 watts at 120 volts requires a
resistance of about 960 ohms. That is a very long piece of
very thin nichrome.

I think for
someone who knows how this works should be a no brainer. I recently saw
an article somewhere that suggested using a toaster or aquarium heater
element, halved , coiled around a small wire and threaded into a
silicone tube. Any advice would be excellent, thank you.

I have a big roll of this sort of thing. I don't remember
the resistance per foot, but it is less than an eight inch
outside diameter. I think it is also covered in a woven
fiberglass sheath. If your address is inside the U.S., I
would be happy to send you some. I would probably cover it
with another plastic tube, if it was to be used in a wet
environment.

BTW, i have seen some online for planted aquariums that use a long
length of wire, which is exactly what I need but seems to be really
long.
http://www.thekrib.com/Plants/Tech/

You might also do a Google search for Tigertail or Beadalon,
which is stainless steel multi strand cable in a nylon
sheath, like tiny aircraft cable. It is intended for bead
stringing, but I have successfully used it as heating
element in motor cycle gloves. The nylon is not appropriate
for line voltage insulation, but you could use a step down
transformer or run it through larger tubing. I think the
smaller sizes are a few ohms per foot. I dipped the ends in
battery acid to digest the nylon cover, and crimped copper
leads onto it. Its main advantage is that it is tough and
flexible.

 

[Lostgallifreyan]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it. It has a 110v plug at one end and is about 8 feet
long. The end has a small knob which I assume is a resistor of some
sort. The actual heating part of the cable is about four feet long, the
rest is just to get to the outlet. Oh yeah it is 15 watts. I think for
someone who knows how this works should be a no brainer. I recently saw
an article somewhere that suggested using a toaster or aquarium heater
element, halved , coiled around a small wire and threaded into a
silicone tube. Any advice would be excellent, thank you.

BTW, i have seen some online for planted aquariums that use a long
length of wire, which is exactly what I need but seems to be really
long.
http://www.thekrib.com/Plants/Tech/

Go to a homebrew shop, get the kind of small heating belt used to heat a
single demi-john. (Demi-john is a gallon jar.) Domestic hardware stores
also probably have a variety of this sort of thing.

 

[Dave]

Maybe something more like a lamp dimmer.


Since the formula that relates voltage wattage and
resistance is W=V^2/R, 15 watts at 120 volts requires a
resistance of about 960 ohms. That is a very long piece of
very thin nichrome.


I have a big roll of this sort of thing. I don't remember
the resistance per foot, but it is less than an eight inch
outside diameter. I think it is also covered in a woven
fiberglass sheath. If your address is inside the U.S., I
would be happy to send you some. I would probably cover it
with another plastic tube, if it was to be used in a wet
environment.


You might also do a Google search for Tigertail or Beadalon,
which is stainless steel multi strand cable in a nylon
sheath, like tiny aircraft cable. It is intended for bead
stringing, but I have successfully used it as heating
element in motor cycle gloves. The nylon is not appropriate
for line voltage insulation, but you could use a step down
transformer or run it through larger tubing. I think the
smaller sizes are a few ohms per foot. I dipped the ends in
battery acid to digest the nylon cover, and crimped copper
leads onto it. Its main advantage is that it is tough and
flexible.

Another wire that works well for low temp heating elements is thermocouple
extension cable. This is basically NiChrome in (usually) a fairly robust
sheath. The pair of cables makes it convenient for an out and return circuit
....

 

[default]

Go to a homebrew shop, get the kind of small heating belt used to heat a
single demi-john. (Demi-john is a gallon jar.) Domestic hardware stores
also probably have a variety of this sort of thing.

I'm using drugstore heating pads to keep my 5 gallon carboy fermenters
up at 18 C when the weather is cold - much cheaper than the heat
belts they sell for the purpose - and it heats from the bottom so
there's no stratification. A couple of sweatshirts keep the light out
and heat in.

 

[John B]

I was wondering if anyone could help me with a design of a heat cable
for my new terrarium. I have on fairly expensive cable and would like
to duplicate it. It has a 110v plug at one end and is about 8 feet
long. The end has a small knob which I assume is a resistor of some
sort. The actual heating part of the cable is about four feet long,
the rest is just to get to the outlet. Oh yeah it is 15 watts. I
think for someone who knows how this works should be a no brainer. I
recently saw an article somewhere that suggested using a toaster or
aquarium heater element, halved , coiled around a small wire and
threaded into a silicone tube. Any advice would be excellent, thank
you.

BTW, i have seen some online for planted aquariums that use a long
length of wire, which is exactly what I need but seems to be really
long.
http://www.thekrib.com/Plants/Tech/

I should try this:

http://www.garden4less.co.uk/soil-warming-cable.asp

 

[JeffM]

[Ridiculously long blockqote]

TRIM YOUR BLOCKQUOTES.

Another wire that works well for low temp heating elements
is thermocouple extension cable.

"Extension cable" is the same as thermocouple wire.

This is basically NiChrome

Depends on WHAT KIND of thermocoupe wire you have.
**TYPE-K** thermocouples use Chromel.

 

[John Fields]

Dave wrote:
"Extension cable" is the same as thermocouple wire.

 

[JeffM]

Not really.
http://www.omega.com/prodinfo/ThermocoupleWire.html

Right. Electrically, *the conductors* are the same.

All other things being equal,
if you were to specify a cable to be used to *produce* heat,
I would think **fabric-covered** would be at the top of the list
(as opposed to *poly-plastic insulation*)
with *extension* vs *sensor* being perhaps an expansion of *that*.

 

[John Fields]

Right. Electrically, *the conductors* are the same.

---
No, they're not. That link:

"What is the difference between Thermocouple grade and Extension
grade wire?
Thermocouple grade wire is wire that is used to make the sensing
point (or probe part) of the thermocouple. Extension grade wire is
only used to extend a thermocouple signal from a probe back to the
instrument reading the signal. The extension grade wire typically
will have a lower ambient temperature limit in which the wire may be
used. Namely, it may pass a signal representing a higher temperature
as received from the probe, but the wire physically may not be
exposed to higher temperatures. Thermocouple wire may be used as
extension wire, but extension grade wire may not be used in the
sensing point (or probe part) of the thermocouple. Part numbers for
extension wire typically begin with an "EX" prefix."

 

[JeffM]

No, they're not. That link:
"...The extension grade wire typically will have
a lower ambient temperature limit..."

They keep saying "wire" where *cable assembly* or *insulation*
would better reflect what they were trying to say.
The metal alloy is specified by the thermocouple type
and the range of deviation allowed is narrow.

 

[Spehro Pefhany]

---
No, they're not. That link:

"What is the difference between Thermocouple grade and Extension
grade wire?
Thermocouple grade wire is wire that is used to make the sensing
point (or probe part) of the thermocouple. Extension grade wire is
only used to extend a thermocouple signal from a probe back to the
instrument reading the signal. The extension grade wire typically
will have a lower ambient temperature limit in which the wire may be
used. Namely, it may pass a signal representing a higher temperature
as received from the probe, but the wire physically may not be
exposed to higher temperatures. Thermocouple wire may be used as
extension wire, but extension grade wire may not be used in the
sensing point (or probe part) of the thermocouple. Part numbers for
extension wire typically begin with an "EX" prefix."

They *may* be the same except for insulation. They certainly are not
the same for precious-metal thermocouples. They are not guaranteed to
be the same. For temperatures that lizards can survive at, it's
unlikely to make a lick of difference.


Best regards,
Spehro Pefhany

 

[Arlet]

They *may* be the same except for insulation. They certainly are not
the same for precious-metal thermocouples. They are not guaranteed to
be the same. For temperatures that lizards can survive at, it's
unlikely to make a lick of difference.

Right. Thermocouple extension wire needs to have a similar Seebeck
coefficient as the thermocouple wire in the sensor itself, otherwise a
temperature gradient along the extension wire could affect the measured
voltage. It may be exactly the same material, but does not need to be,
as long as the Seebeck coefficient is close enough for the expected
(lower) temperature gradient (and absolute temperature) of the
extension wire. If a manufacturer uses different material, the
replacement is probably cheaper and/or has lower resistance allowing it
to be longer without causing unacceptable voltage drop.

For the purpose of making a heater cable, there's no guarantee that
arbitrary thermocouple extension wire is suitable. Some extension wires
even use copper! On the other hand, some extension wire *may* be
suitable, but you'll need to check which alloys are used, and what
their properties are.

 

[Dave]

Right. Thermocouple extension wire needs to have a similar Seebeck
coefficient as the thermocouple wire in the sensor itself, otherwise a
temperature gradient along the extension wire could affect the
measured voltage. It may be exactly the same material, but does not
need to be, as long as the Seebeck coefficient is close enough for
the expected (lower) temperature gradient (and absolute temperature)
of the extension wire. If a manufacturer uses different material, the
replacement is probably cheaper and/or has lower resistance allowing
it to be longer without causing unacceptable voltage drop.

For the purpose of making a heater cable, there's no guarantee that
arbitrary thermocouple extension wire is suitable. Some extension
wires even use copper! On the other hand, some extension wire *may* be
suitable, but you'll need to check which alloys are used, and what
their properties are.

You are all correct, of course. This illustrates the difficulty of knowing
at what level of detail to pitch a reply ! The reason I went down the
'thermocouple extension' route was because I found it difficult to buy
nichrome wire in reasonable quantities, and then you still have the problem
of a suitably rugged sheath. Anyway, I made a successful series of telescope
anti-dew heaters from type K extension wire (RS 151-209), running about 15w.
I should probably have mentioned that this is strictly a low voltage (12v)
solution.

Dave

 

[Ban]

They *may* be the same except for insulation. They certainly are not
the same for precious-metal thermocouples. They are not guaranteed to
be the same. For temperatures that lizards can survive at, it's
unlikely to make a lick of difference.


Best regards,
Spehro Pefhany

Measurement wire is used only for a few cm where the heat gradient is the
highest. Its alloy is accurately controlled to produce the exact seebeck
coefficient. Extension wire can be of much poorer quality, since there is
very little voltage produced across it.