Field Wireable Relay
- Thread starter Mcamnl
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renosteinke
Senior Member
- Location
- NE Arkansas
The question you ask is asked in such a way that I worry if your ambition might, perhaps, exceed your competence. You bring up a few delicate issues.
To start with ... what is a 'field wireable' relay? One with screws that you directly attach wires to, rather then plug into a base? Sure, they exist ... we call them 'contactors' ... but they're a lot larger than the little 'ice cube' relays used in control circuits. There are also nifty little 'DIN wafers" that snap ont to DIN rails, and take up very little space. (They sort of resemble skinny circuit breakers). It doesn't take a whole lot of panel experience to learn of these things.
A "listed" panel is listed just the way it came from the factory. In general, you're not supposed to add or change anything in it. Not very many panels are 'listed.' What is usually found is a 'listed' steel box with all manner of things put inside by others, later on. It's up to you to maintain clearances, design in circuit protection, and protect the enclosure.
No room? Well, that's a concern. You're supposed to mount things, not just have them hanging by their wires.
To start with ... what is a 'field wireable' relay? One with screws that you directly attach wires to, rather then plug into a base? Sure, they exist ... we call them 'contactors' ... but they're a lot larger than the little 'ice cube' relays used in control circuits. There are also nifty little 'DIN wafers" that snap ont to DIN rails, and take up very little space. (They sort of resemble skinny circuit breakers). It doesn't take a whole lot of panel experience to learn of these things.
A "listed" panel is listed just the way it came from the factory. In general, you're not supposed to add or change anything in it. Not very many panels are 'listed.' What is usually found is a 'listed' steel box with all manner of things put inside by others, later on. It's up to you to maintain clearances, design in circuit protection, and protect the enclosure.
No room? Well, that's a concern. You're supposed to mount things, not just have them hanging by their wires.
Maybe I didn't word the question correctly.
We are a UL listed panel shop. We are making plans for a rather large 4 door enclosure with 2 big panels that needs to be UL listed.
There are multiple things that are going to be wired to this once the panel is one site. Some things need to go to relays, others need to go to
manual self-protected combination motor controllers. Our UL rep was in yesterday and after doing a bit of searching determined that the motor controllers
are not suitable for field connections so we need to have a bunch of terminal blocks installed and wired for field connections.
The same is looking to be true for all of the relays.
I am wondering if there is a relay that is suitable for field connections without having to wire it to a terminal block.
We are just trying to find an alternative to adding a couple hundred more terminal blocks to this panel.
We will if we have too, just wondering if there was another way.
We are a UL listed panel shop. We are making plans for a rather large 4 door enclosure with 2 big panels that needs to be UL listed.
There are multiple things that are going to be wired to this once the panel is one site. Some things need to go to relays, others need to go to
manual self-protected combination motor controllers. Our UL rep was in yesterday and after doing a bit of searching determined that the motor controllers
are not suitable for field connections so we need to have a bunch of terminal blocks installed and wired for field connections.
The same is looking to be true for all of the relays.
I am wondering if there is a relay that is suitable for field connections without having to wire it to a terminal block.
We are just trying to find an alternative to adding a couple hundred more terminal blocks to this panel.
We will if we have too, just wondering if there was another way.
GeorgeB
ElectroHydraulics engineer (retired)
- Location
- Greenville SC
- Occupation
- Retired
This UL statement is opposite (I think) the standard practice when I did control panel design. Our rule was that every wife leaving the panel EXCEPT motor "T-leads" over (I think) #10 had to be from a terminal strip. We located large starters conveniently for direct field wiring.
Now the motor controller in your case may differ from our starters ... we didn't put "combination starters" inside a panel.
Today, with sophisticated communication bus, something like Profibus or similar would allow field (remote) installation of inputs (and outputs)
Now the motor controller in your case may differ from our starters ... we didn't put "combination starters" inside a panel.
Today, with sophisticated communication bus, something like Profibus or similar would allow field (remote) installation of inputs (and outputs)
Last edited:
renosteinke
Senior Member
- Location
- NE Arkansas
So you are "the factory." Well, that detail changes everything ...
UL can be quite annoying; sometimes it seems all they do is cash your check and tell you 'no.' They're not in the design business, they will say. Not very nice of them, is it? Keep in mind that the Rep's entire 'education' has been from inspecting the plants of you and your competitors, and he really doesn't want to be accused of sharing one firm's solution with another.
Well, when you got your certification, I'm sure you purchased copies of the relevant standards. If you had any sense, you then made a gazillion "illegal" copies and have them all over your plant. If not, well, ask the UL guy nicely, and he just might be able to produce one for you. Whatever the source, read it. Carefully.
I suspect that the objection to 'field wiring' has to do with the clearance requirements. Terminal strips are a way to place the connections where you have the necessary clearances; they also provide the insulating barriers that allow clearances to be reduced.
UL can be quite annoying; sometimes it seems all they do is cash your check and tell you 'no.' They're not in the design business, they will say. Not very nice of them, is it? Keep in mind that the Rep's entire 'education' has been from inspecting the plants of you and your competitors, and he really doesn't want to be accused of sharing one firm's solution with another.
Well, when you got your certification, I'm sure you purchased copies of the relevant standards. If you had any sense, you then made a gazillion "illegal" copies and have them all over your plant. If not, well, ask the UL guy nicely, and he just might be able to produce one for you. Whatever the source, read it. Carefully.
I suspect that the objection to 'field wiring' has to do with the clearance requirements. Terminal strips are a way to place the connections where you have the necessary clearances; they also provide the insulating barriers that allow clearances to be reduced.
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