Safety in using barrier terminal blocks with cover? CE Certification?

Thread Starter

Mahonroy

Joined Oct 21, 2014
339
Hello,
I am wanting to create a device that has a barrier terminal block incorporated into the design for wire hookup. I cannot seem to find any information on if this is considered acceptable or not (from a safety standpoint), however, I see a decent amount of designs using them. The basic idea is that you provide the device with 120vac power, and there are a few low voltage signal inputs/outputs as well. The device has a screen and buttons on it, and is meant to be mounted to something for use.
Here is the component I am talking about, and a few other designs I have come across that show how it would be used:
barrier_terminal_block1.jpg
barrier_terminal_block2.jpg
barrier_terminal_block3.gif

Are there any precautions that you are aware of that I might need to take? Thanks, and any help/advice is greatly appreciated!
 

MaxHeadRoom

Joined Jul 18, 2013
23,342
The basic rules are any terminals or connection that carry voltage that is above that considered a safe level shall be in an enclosure that requires either a mechanically interlocked cover, or shall be secured by some kind of fastener that requires a tool for removal, before exposure to the internal connections are possible.
If any terminals are exposed, on the outside of the enclosure they shall be of Low Voltage and Galvanically isolated from any internal high voltage.
Max.
 

Thread Starter

Mahonroy

Joined Oct 21, 2014
339
The basic rules are any terminals or connection that carry voltage that is above that considered a safe level shall be in an enclosure that requires either a mechanically interlocked cover, or shall be secured by some kind of fastener that requires a tool for removal, before exposure to the internal connections are possible.
If any terminals are exposed, on the outside of the enclosure they shall be of Low Voltage and Galvanically isolated from any internal high voltage.
Max.
Hi MaxHeadRoom, thanks for the info! The top image I posted (with the clear orange cover that snaps down), is that considered a "mechanically interlocked cover", and in this case it would be acceptable?
 

MaxHeadRoom

Joined Jul 18, 2013
23,342
Hi MaxHeadRoom, thanks for the info! The top image I posted (with the clear orange cover that snaps down), is that considered a "mechanically interlocked cover", and in this case it would be acceptable?
Not really, it can easily be flipped up, if easily accessible.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
23,342
The second unit is usually intended to be mounted in a Electrical enclosure, where this would be fitted with a mains disconnect that has to be operated to open the enclosure, what market is this intended for? Industrial or Residential?
General requirements can be found in NFPA79 which is Electrical Standards for Industrial Machinery.
Max.
 

Thread Starter

Mahonroy

Joined Oct 21, 2014
339
The second unit is usually intended to be mounted in a Electrical enclosure, where this would be fitted with a mains disconnect that has to be operated to open the enclosure, what market is this intended for? Industrial or Residential?
General requirements can be found in NFPA79 which is Electrical Standards for Industrial Machinery.
Max.
Thanks again for the info! Its intended to be industrial. What would be the difference here if it was residential or industrial?
I looked up the NFPA79, here is the document I found:
http://www.infoplc.net/files/documentacion/seguridad_normativa/infoPLC_net_2012-01-02-06-27-401.pdf
Lots of info in there haha unfortunately I was not able to find this thing in there since its so large.
 

MaxHeadRoom

Joined Jul 18, 2013
23,342
Section 79-12 and ch5 shows some requirements, basically when designing for safety, common sense prevails, IOW if you have a terminal strip that is easily accessible and can be accessed while live just by flipping up a simple cover, it probably won't fly.
Could it be enclosed inside a general enclosure of the unit?
Max.
 

mcgyvr

Joined Oct 15, 2009
5,394
There is also a big difference in if your device is standalone (listed product) or a component in a larger system (recognized component)..
A listed component can have no "conditions of acceptability" but a recognized component can..

You need to find out what standards you product needs to be compliant with (and approved) before you design anything or you may be wasting a lot of time and money....
Then you purchase those standards and read until you are blue in the face.. Most standards will then link to another standard that you need to purchase and the spider web continues..
Then you design ensuring you meet all those requirements..

NFPA is probably the least of your worries and rarely the sole standard a product is judged by.. UL/CSA (US and Canada).. or IEC/EN,etc... is more likely. and there are many more depending on what you product is and were you intend on selling it..
 

Thread Starter

Mahonroy

Joined Oct 21, 2014
339
Thanks again for the good info!

So here is a question; what if I put the terminal blocks on the back side of the device, so when its mounted to something, that stuff is mostly covered up?

I believe this device would be considered a component to a larger system, since its up to the user how they want to use it, how they want to wire it up, etc.

It shouldn't be completely enclosed inside another box because there is a display that needs to be seen, and a rotary knob to change settings.
 

MaxHeadRoom

Joined Jul 18, 2013
23,342
If it is intended to be mounted on a protected enclosure with the power terminals not accessible from the outside, you should be OK.
Max.
 
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