my kingdom for a pressure terminal open frame 120V coil SPST relay

archibald tuttle

i would have thought this was the vanilla of relays but all i can find is chocolate i guess, e.g. Magnecraft 199ADX-4

This relay has screw terminals but not even wire retainers nevermind pressure terminals (which are an option on the 50amp version e.b. 199ADEX-4. I couldn't even find any other manufacturer offering anything like this. I know icecubes are cool, but i view their plug in bases as just as much of a potentional problem as contacts or tab connections leading to failure. Now, i think the unlabeled relay i'm replacing in a generic enclosure probably dates to a boiler changeout the end of the last century so it did go 20 years (well, it started screwing up last year but i barked up the wrong tree ) so i'm not saying that was an inadequate life, but i think pressure connections are most efficient and provide best connection and if one limits any excess load from connections (crimp fork terminals were used in this case to then slide under the screws) that is going to stretch the contact life even further on these modest loads (8 amps with 20 amp start condensate pump).

So just asking if i'm missing some obvious source for modest amperage pressure terminal relays aimed at us field wiring folks that would fit in existing nema enclosures. There are plenty of contactors out there that you can have for next to nothing that would do the job but they aren't going to fit in the existing enclosure which would be common in the field.

The other possiblity i examined was a 25 amp solid state relay but the specs say 25 amps with a heat sink and the specs you have to chase because they are not on the website are that you can only go to 4 amps without the heat sink which doubles the cost - and makes me wonder if the relay is going to last forever why they don't just sell them as a unit.. Maybe its just marketing or allows the same relay to be sold for both high and low amp applications and maybe it would last forever in the field, so doing twice the investment to move from magnetic open frame to solid state would have been worth it but i went with the tried and true open frame magnetic for the time being, but wondering if any other brave souls have made 'the switch' and have any observations on their satisfaction so far.

thanks,

brian

JUGHNE

I have saved the steel box that the standard refrigeration defrost timers come with, also the box that other time clocks use......just changing the guts using the existing mounted box.

These have worked well to mount relay/contactors in.
Steel, 1/2" KO, and lockable door.
You can get a 30 amp 2Pole AC contactor with 120 VAC coils.
I use both poles for the 120 loads, sharing the amp load by switching both hot and neutral.

RPK

Can you explain what you mean by pressure terminals? What about something like this:

https://www.functionaldevices.com/downloads/datasheets/RIBM2401B.pdf

They also make the enclosed relays that mount in an electrical knockout rated at higher amperages than the fairly ubiquitous RIBU1C.

Like this:

https://www.functionaldevices.com/downloads/datasheets/RIB01P.pdf

Many of their relays are available with override switches which are pretty handy for the service person.

archibald tuttle

Jughne, thought about that. i have saved the boxes from the clunky old time clocks to turn lights on at night. With the modest size enclosure already in place I was professing the dilemma re the tradeoff of time to change out vs. a relay that would fit existing enclosure, but i'm with you as to the backup solution.

and interestingly, the magnecraft SPST relays are double make. I couldn't really get a straight answer from their engineer if that didn't amount to two sets of points to fail or it effectively spread the closing load across the two sets of points, i would think it wouldn't work that way because there might be milliseconds of difference in the make of the twin points but maybe i'm just a skeptic. magnecraft engineer suggested this was engineered for DC service. I'm hadn't thought about whether DC was harder on points. I've got a 1950s DC elevator board that has massive points for the amperages its transmitting so maybe so . . .

RPK, wish i had seen that before i bought the old standard, but that will be my next replacement relay. i'm going to put a couple on the shelf. If i'm reading the data sheet right the same relay accepts either 24V or 120V to the coil, that's huge. and it's designed sizewise to fit the typical smaller relay enclosures out there and i like the relatively convenient wiring blocks. i would describe those terminals as block screw or modified screw or screw pressure. A true pressure terminal is similar to larger electric connections and is designed for a straight stripped length of wire to be inserted and then the terminal tightened to hold it and works equally well with stranded or solid wire, e.g. this 199ADEX (the E designates pressure terminals and they are only available special order or in OEM applications on the heavier amp versions, i guess i'm just retentive looking for them on the 40 amp version:



whereas with an open screw terminal you either need to carefully bend a solid wire around the screw and insure it is retained under the screw head when tightening or add a fork terminal to a stranded wire. So the pressure terminal cuts install time in the field while giving a better connection. Many of the higher amp contactors have them and the modified style provided in the RIB you linked is a next best alternative. But I'm not even sure how to designate or name that connection so you can look for it.

Don't know why the internet never surfaced those open RIBs when i searched. I did see the box style, which i'm sure just has similar technology in the box. I did see those and find you could get higher amperage versions but my penchant against black boxes (not that the open one isn't effectively a black box but at least you can see the relay and parts even if it isn't plug and play component wise) and i prefer terminals to wire nuts although the knockout mount style is probably good goto if you don't have an enclosure.

thanks

brian

PS any takers on the Omron solid states?

archibald tuttle

RPK - and add an S for the service switch. e.g. RIBM2401SB i've been begging TACO and Caleffi for this for years. If RIB made a track style double pull relay like this with an override/off switch and power and call leds i'd chuck my 50x relays in a heartbeat and build my own on a track. just sayin'. Unfortunately they have a nice 10 amp double pull but it doesn't have the override switch on it (unless you go back in the box).

They ought to call their modular line RIYB as in "relay in your box".

One thing I did find after haranguing their tech guy tim for some time is that they do make SIBs , switch in a box, which i can append to TACO or Caleffi relays in some logical order along knockouts in order to provide service switching. e.g SIBLS, although the LED indicator, unfortunately, is just a power indicator and not a call indicator. nothing's perfect or i would have nothing to whine about.