I'm trying to replace the built-in mechanical thermostat on an old
Fasco Industries 8- foot, 240 volt electric baseboard heater with a
programmable line voltage thermostat, either a Honeywell CT1950 or an
Aube Technologies TH106. Problem is I'm supposed to choose between 2
programmable thermostats - the Honeywell CT1950A which is for 2 wires
or the Honeywell CT1950B which is for 4 wires, and I have no idea
which one I need.

Questions:

1. Is the CT1950A or B just one thermostat that can be wired in 2
different ways, or are we talking 2 different thermostats altogether?

2. In any case, how can I tell if I need a 2-wire thermostat or a
4-wire thermostat? I looked at the existing wiring and noticed that
there are only 2 wires coming out of the wall directly from the
breaker panel. Then there appears to be 4 wires, all of them colored
red, connected to the built-in thermostat mounted on the heater itself
- 2 red wires going in and 2 red wires coming out. I have not traced
where these wires going in and out of the existing thermostat are
coming from.

As you can tell, I am really electrically challenged, so please pardon
me if the question sounds stupid. But I really have a problem
understanding electrician's English - when they say 2-wire or 4-wire,
are they talking about the wires coming out of the wall or the wires
coming out of the thermostat?

Any help will again be appreciated. Thanks.

According to Filipo :
I'm trying to replace the built-in mechanical thermostat on an old
Fasco Industries 8- foot, 240 volt electric baseboard heater with a
programmable line voltage thermostat, either a Honeywell CT1950 or an
Aube Technologies TH106. Problem is I'm supposed to choose between 2
programmable thermostats - the Honeywell CT1950A which is for 2 wires
or the Honeywell CT1950B which is for 4 wires, and I have no idea
which one I need.

A bit of background: a line voltage thermostat is one that slips
in series with the power feed to the heater and controls the heater
by switching the power feed off and on. As contrasted with other
thermostats which activate a seperate relay to switch the power feed
to the heater.

The CT1950x thermostats are line thermostats, which means that they
take power in (via the Lx terminals) and switch the output power on the
Tx terminals.

The only difference between the CT1950A and B is that the CT1950A
switches only one wire (single pole switch), and the B model switches
two wires (double pole switch).

[Ie: electrically, the CT1950A simply connects/disconnects wire T1 from
L1. Electric simply connects/disconnects wire T1 from L1 and T2 from
L2.]

http://content.honeywell.com/yourhom.../CT1950faq.htm

You use single pole thermostats on 120V heaters, because there's only
one hot wire present (total of two: neutral plus one hot), and that's
the only one you need to switch.

240V has two hot wires (no neutral). Preferably and ideally you should
use two pole thermostats for 240V heaters, so that both hot wires are
simultaneously detached - otherwise, the element would be live even when
the thermostat has the heater turned off. However, most codes do not seem to
insist on that - which has always seemed very odd to me.

I always use 2 pole for 220V.

Questions:

1. Is the CT1950A or B just one thermostat that can be wired in 2
different ways, or are we talking 2 different thermostats altogether?

2. In any case, how can I tell if I need a 2-wire thermostat or a
4-wire thermostat? I looked at the existing wiring and noticed that
there are only 2 wires coming out of the wall directly from the
breaker panel. Then there appears to be 4 wires, all of them colored
red, connected to the built-in thermostat mounted on the heater itself
- 2 red wires going in and 2 red wires coming out. I have not traced
where these wires going in and out of the existing thermostat are
coming from.

It sounds as if the preexisting thermostat is 2 pole. You will need
to replicate how it interconnects.

As you can tell, I am really electrically challenged, so please pardon
me if the question sounds stupid. But I really have a problem
understanding electrician's English - when they say 2-wire or 4-wire,
are they talking about the wires coming out of the wall or the wires
coming out of the thermostat?

When they say "4 wire X", they really mean "4 wires connected to X".
What that actually means electrically depends on what X _is_.

Poor terminology.

The electrician should _really_ be saying "two pole" (CT1950B) versus
"single pole" (CT1950A).

Any help will again be appreciated. Thanks.


--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

(Chris Lewis) wrote in message ...:

240V has two hot wires (no neutral). Preferably and ideally you should
use two pole thermostats for 240V heaters, so that both hot wires are
simultaneously detached - otherwise, the element would be live even when
the thermostat has the heater turned off. However, most codes do not seem to
insist on that - which has always seemed very odd to me.

I always use 2 pole for 220V.


Thanks, Chris, your explanation is crystal-clear and most
enlightening. Now I can actually visualize a circle where a single
pole circuit resembles a dented egg (only one side broken) while a
double pole circuit resembles a halved egg (both sides sliced through
and broken).

Now here's my problem - I'm stuck with 3 brand-new thermostats that I
have already purchased on-line based on my Internet research - a
2-wire Honeywell CT1950A, a 2-wire Ouellet OTH510, and a 2-wire Aube
Technologies TH106. It seems that in Canada (I'm actually in the US),
they don't make any distinction between single pole and double pole
switches for 240-volt baseboard heaters - they use 2-wire thermostats
intechangeably for both 2-wire and 4-wire applications.

So I'm focusing on your statement that "preferably and ideally ...use
2 pole thermostats... etc." They sound like permissive, not mandatory,
requirements, i.e., I should but I don't have to. I guess my question
is - is there a safety issue if 1 wire remains live in a 240-V
circuit? Since the 2nd wire is disconnected, is there any chance the
live wire could find a way to return to ground and form a complete
circuit? Does this constitute, God forbid, a fire hazard? Given the
new information that you so kindly provided, I'm thinking that maybe
when winter's gone, I'll just go to my breaker panel and turn off the
live feed to all baseboard circuits.

It makes me wonder why thermostat manufacturers continue to market
2-wire thermostats as suited for 240 volt applications, instead of
reserving 2-wire units only for 120 volts and 4-wire units for 240
volts.

Thanks for any additional input.

Filipo wrote:

(Chris Lewis) wrote in message ...:

240V has two hot wires (no neutral). Preferably and ideally you should
use two pole thermostats for 240V heaters, so that both hot wires are
simultaneously detached - otherwise, the element would be live even when
the thermostat has the heater turned off. However, most codes do not seem to
insist on that - which has always seemed very odd to me.

I always use 2 pole for 220V.


Thanks, Chris, your explanation is crystal-clear and most
enlightening. Now I can actually visualize a circle where a single
pole circuit resembles a dented egg (only one side broken) while a
double pole circuit resembles a halved egg (both sides sliced through
and broken).

Now here's my problem - I'm stuck with 3 brand-new thermostats that I
have already purchased on-line based on my Internet research - a
2-wire Honeywell CT1950A, a 2-wire Ouellet OTH510, and a 2-wire Aube
Technologies TH106. It seems that in Canada (I'm actually in the US),
they don't make any distinction between single pole and double pole
switches for 240-volt baseboard heaters - they use 2-wire thermostats
intechangeably for both 2-wire and 4-wire applications.

So I'm focusing on your statement that "preferably and ideally ...use
2 pole thermostats... etc." They sound like permissive, not mandatory,
requirements, i.e., I should but I don't have to. I guess my question
is - is there a safety issue if 1 wire remains live in a 240-V
circuit? Since the 2nd wire is disconnected, is there any chance the
live wire could find a way to return to ground and form a complete
circuit? Does this constitute, God forbid, a fire hazard? Given the
new information that you so kindly provided, I'm thinking that maybe
when winter's gone, I'll just go to my breaker panel and turn off the
live feed to all baseboard circuits.

It makes me wonder why thermostat manufacturers continue to market
2-wire thermostats as suited for 240 volt applications, instead of
reserving 2-wire units only for 120 volts and 4-wire units for 240
volts.

Thanks for any additional input.

It's covered in Art. 424-19 (NEC).

Basically, in a one-family house, you are permitted to use a
single-pole (2W) thermostat and then either the branch circuit
(breaker) or the service disconnect (main breaker) serves as
the disconnect for the heater.

So, if you were going to work on the heater, you should
remember to switch off the breaker first...

Jim

According to Speedy Jim :
Filipo wrote:
(Chris Lewis) wrote in message
...:
I always use 2 pole for 220V.

So I'm focusing on your statement that "preferably and ideally ...use
2 pole thermostats... etc." They sound like permissive, not mandatory,
requirements, i.e., I should but I don't have to. I guess my question
is - is there a safety issue if 1 wire remains live in a 240-V
circuit? Since the 2nd wire is disconnected, is there any chance the
live wire could find a way to return to ground and form a complete
circuit?

Chance? Yes, but extremely remote (assumes for example, circuit is otherwise
miswired, heater malfunctions). Significant enough to pay a bit extra?
That's something only you can answer.

Does this constitute, God forbid, a fire hazard? Given the
new information that you so kindly provided, I'm thinking that maybe
when winter's gone, I'll just go to my breaker panel and turn off the
live feed to all baseboard circuits.

I kill the breakers to all the heaters regardless. Saves money if
a T-stat gets accidentally fiddled or fails on. Makes winter startup
a distinct process of cleaning them, turning them on, and
checking them all at once.

It makes me wonder why thermostat manufacturers continue to market
2-wire thermostats as suited for 240 volt applications, instead of
reserving 2-wire units only for 120 volts and 4-wire units for 240
volts.

It's covered in Art. 424-19 (NEC).

Basically, in a one-family house, you are permitted to use a
single-pole (2W) thermostat and then either the branch circuit
(breaker) or the service disconnect (main breaker) serves as
the disconnect for the heater.

Notice how that's "one family"? It's one of those exemptions specifically
intended to lower the cost of wiring in the least risky environment.
[Even tho in many cases it makes no difference to the cost of the device,
and only a slight difference in labour.]

Notice how that doesn't apply to commercial, industrial, or multi-person
dwellings. There's a strong hint there.

Obviously, the NEC has made a tradeoff judgement here. The question is, do you
agree with their judgement for _your_ specific circumstances?

So, if you were going to work on the heater, you should
remember to switch off the breaker first...

Aye, there's the rub ... some people don't. It really shouldn't
be hinted that _not_ turning off the breaker before working on a
circuit is acceptable practise.

I personally prefer exceeding code as far as is practical. So
if I stupidly forget to switch off the breaker, or something else
like the thermostat contacts sticking, then I don't find out the hard way.

When the cost difference is minor (or non-existant), as there would be
with, say, just one T-stat to buy, there's no contest - 2 pole it is.

If I already had a single-pole T-stat, I likely would decide to use
2 pole. But if I had three? Probably not.

If I was wiring whole subdivisions, I almost certainly wouldn't bother with
two pole.

Etc.

I've read all the replies and am still looking for wiring diagrams, which would provide more clarity than volumes of words and terminology. We all like to talk but a wiring diagram communicates explicitly. Is displaying a wiring diagram not possible on these websites?

--
For full context, visit https://www.homeownershub.com/mainte...re-481838-.htm

"Wirenut" wrote in message
roupdirect.com...
I've read all the replies and am still looking for wiring diagrams, which
would provide more clarity than volumes of words and terminology. We all
like to talk but a wiring diagram communicates explicitly. Is displaying
a wiring diagram not possible on these websites?

Easy to post a link to a wiring diagram on drop box etc or various other
sites

Tad unlikely that anything will show up 17 years later now tho.

--
For full context, visit
https://www.homeownershub.com/mainte...re-481838-.htm

On 1/30/21 2:45 PM, Wirenut wrote:
I've read all the replies and am still looking for wiring diagrams,
which would provide more clarity than volumes of words and terminology.
We all like to talk but a wiring diagram communicates explicitly.Â* Is
displaying a wiring diagram not possible on these websites?


Images on Usenet or HomeMoanersHub are not supported. However URL links
to images are. Look here and see if anything answers your problem.

https://www.google.com/search?hl=en&...wiring+diagram

or https://tinyurl.com/y6dbzsg8

On Sun, 31 Jan 2021 07:13:14 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the trolling senile asshole's latest troll**** unread

--
Website (from 2007) dedicated to the 86-year-old trolling senile
cretin from Oz:
https://www.pcreview.co.uk/threads/r...d-faq.2973853/

On Sat, 30 Jan 2021 19:45:02 +0000, Wirenut posted for all of us to digest...


I've read all the replies and am still looking for wiring diagrams, which would provide more clarity than volumes of words and terminology. We all like to talk but a wiring diagram communicates explicitly. Is displaying a wiring diagram not possible on these websites?

For what specifically? Make model horsepower?

--
Tekkie

Thank you.
Ductless heat pumps run harder as the temperature differential increases, slower as it decreases and maintain a more consistent temperature than with the off- on surges common to baseboards. I think Ive seen wall heaters which incorporate that technology. Is that technology available for baseboards?

--
For full context, visit https://www.homeownershub.com/mainte...re-481838-.htm