New and interesting information about Wheelock electromechanical horns

Another thing I’m interested in finding out is whether or not the terminal versions of the 30-series horns just by themselves (e.g. 32PT, 34T, 36T) came out the same time as their pigtail counterparts. I know it was the case with the 7000 series. But here’s the thing. The 30 series horns came out around the late 1960s/early 1970s; and I’m not sure if there were any fire alarm notification appliances that had screw terminals for connection during the '60s and '70s. Back then, most NA’s used pigtails; I think terminals became more common in the '80s, particularly once Wheelock discontinued offering notification appliances with pigtails.

Also, I highly doubt the 32P and 32PT were in production when the grille was redesigned. But I could be wrong. Here is my thinking why this is probably the case. When I got my Wheelock 7002T last year (it was new-in-box and manufactured in March of 1990), the pamphlet that came with the device only listed the series 7001T, V7001T, 7002T, 34T, 34T-WS, and 36T. And when I saw another Wheelock ad from c. 1986, same thing.

I just came across an old instruction manual somewhere, and here’s how Wheelock specifies polarization of its devices.

Non-polarized: the horn leads are all black and strobe leads are blue
Polarized: for horn leads, red is positive and black is negative; for strobe leads, blue is positive while white is negative. The 7000 series horn/strobes only use black and red wires due to the horn and strobe being wired in series.

And this brings me to something I may have just discovered. The 32 series horns were probably the only Wheelock electromechanical horns to be offered in non-polarized and polarized versions. And that’s why it has “P” in the model number. The 34, 7001, and 7002 horns on the other hand were only offered in polarized versions, hence, there’s no “P” moniker.

However, when it comes to the pigtail and terminal versions, Wheelock kept the “T” moniker, even after pigtail connectors were discontinued at the end of 1985.

That does make the most sense, P meaning power makes no sense given that the different model numbers are the powers difference.

  • 32-24 operates at .125 amps DC
  • 34-24 operates at .063 amps DC
  • 33-24 probably somewhere in between, possibly .094 amps
  • 34-12 at .125 amps
  • 32-12 would logically operate at .25 amps

The fact that the link above mentions only “T” models makes me think that the 32PT may have continued after the introduction of the vandal resistant grille, but was probably discontinued shortly after. Same goes for the 7003T (flush version of the 7004T), which I saw listed on a data sheet in the mid-80s, but wasn’t listed on later ones.

It’s definitely fascinating to think of how many rare variants of the 30/7000 series there are.

Yeah, it definitely is. I wonder if there’s a higher current 30 horn, or if that was just for the DC horns?

The highest current 30 horns are the 35T-6 and the 31T-6, both of which are AC horns.

Also according to the link, Wheelock even made the 31T-WS (4-wire 7004T) as well as the 35T-WS. Another interesting thing is that the 31T and 7004T aren’t polarized, but the 35T is polarized AC. Perhaps those models were discontinued shortly after the grille redesign, along with 32PT, 7003T, and all the models with pigtail wires (including the 34 and 7002). I say this because they weren’t listed on the data sheet that I got with my 7002T (it was manufactured in 1990).

And one other thing worth mentioning. If it were the case that Wheelock began switching from pigtail leads to screw terminals around the same time the horn’s grille was redesigned, I don’t think there would’ve been any need to have the “T” moniker in the model number. If you think about it, products that were made after the 7000 series had screw terminals, but didn’t have a “T” moniker to indicate that. The only reason Wheelock had the “T” moniker was because they offered both pigtail and terminal versions simultaneously, and figured making the distinction would make it easier on potential buyers.

There were also times where I was a little confused about “T” standing for tamper resistant grille when I also came across Wheelock bells that had “T” in the model number (e.g. 46T).

Those things are near deafening, I’ve been under a few when they have gone off and It nearly gave me a heart attack.

I think for the 32 series horns, Wheelock offered both non-polarized and polarized options at the same time, which is why the model numbers were different. Same thing applied to the wire lead and screw terminal models; they were also given different model numbers as both options were offered simultaneously.

I just found out some more information about these horns.

  • The 33 series is actually the non-polarized version of the much-more-common 34 series. Both operate at 0.063 amps

  • There was also a 37 series, which was the non-polarized version of the 36 series.

  • Because of this, as well as there being the 31 series (non-polarized AC) and the 35 series (polarized AC), only the 32 series horns (0.125 amps) had the “P” moniker in the model number for the polarized version.

  • Wheelock continued to offer both pigtail and terminal versions until the end of 1985 / beginning of 1986; by that point, the pigtail models were finally discontinued. In the installation manual that I saw, the “T” moniker was in parentheses; so that’s how I figured this out. I would also say that most of the less common 30 series horns (32, 33, 35, and 37) were discontinued around the same time as the pigtail models. The 31/31T and 34/34T series were the most common 30 series horns, which is why the less common models ended up being discontinued.

I’ve noticed that recently.

  • Gloss finish – generally seen on the open grille models

  • Matte finish v1 – very late open-grille models and earlier closed-grille models (c. 1984-1987)

  • Matte finish v2 – later closed-grille models (c. 1988/1989-1994)

I actually have an open-grille pigtail 30-series horn with a smooth, glossy finish (a “33-24” specifically), along with two closed-grille “textured” matte 30-series horns: a standard 34T-24 with terminals, & a “34-24” with pigtails. The 7002T-24 I have also has a “textured” matte finish to it (it has a closed grille & terminals like most 7002T-24s as well, though I’m not sure if the 7000-series was ever offered with pigtails, if they were they must be very rare).

The 7000 series was offered with pigtails as well as screw terminals. The pigtail version is the one that doesn’t have “T” in the model number (e.g. 7002-24, 7001-24); it’s just that most had an open grille because they were discontinued late 1985 / early 1986.

That being said, I have three 7002T-24s in my collection now. One is an open-grille version with a gloss finish, manufactured in 1981. The other two are closed-grille models: one manufactured in 1985 (rougher matte finish, black diaphragm) and the other manufactured in 1990 (smoother matte finish, silver diaphragm).

Oh yeah, didn’t think of that.

All of the devices I listed have black diaphragms (though oddly enough they’re all silver on the back. Not sure what the story is behind some horns sometimes having silver diaphragms & other times black ones however).

It’s mostly the open-grille models which had the black diaphragms behind the grille. Very early closed-grille models also had this. But starting in the fall of 1985, Wheelock chose not to paint the diaphragms; and I think this was probably done to save time and money.

Another interesting fact is the early models had flat screws (including the terminals on the “T” models), and then they switched to Phillips screws about a year after the grille redesign (around the same time the non-“T” models were discontinued if not right before).

Ah okay. I also meant other horns that can have silver or black diaphragms like Simplex’s 2901-9838 too though.

That is interesting!

The same can be said about the Simplex 2901-9838; the later models have silver diaphragms