Using Fuses inside Hazardus area

[ilan7]

Hi all
We need to use small fuses (1 to 6 Amp, 24 VDC) in Class I Zone 2 (Div. 2) hasardus area. After doing some research, found out that ceramic fuses conseder to be "None Sparking" and are allowed. Wondered if anyone have more solid argument or another (better) solution.

 

[ICman]

Ceramic fuses would be the way to go, IMHO. However, you need to guarantee that you won't get an arc if you remove the fuse from the fuseholder. Either install a (sealed) disconnect switch, or a special fuseholder (don't know, never seen one).

This is a Zone 2 (Div. 2) location, which means you do not normally have an explosive gas mix present. Seems like an arc when removing a fuse wouldn't be a big deal. Problem is, what if you have to do it when there IS a hazardous atmosphere? According to Murphy's Law ...

... Steve

 

[ilan7]

Thanks Steve.
I'm trying to make it safe by adding a sign next to the fuses: "Disconnect power before openning fuse holders".

What we actully did was moving the PLC modules from the control room to be located inside local Junction Boxes next to the field instruments. The saving start with wires terminals and connections, But the real saving is the time and simplicity of the checkings, operation and finding errors. All the system is rated for the Zone 2 and only the fuses are not 100% certified for it. Until now I had projects build this way in the US, Canada, and Nicaragua. Now I have another project on going in Japan and in New Zealand. Hope to pass the local authorities check soon.

 

[MarkTX]

I had this concern a few years ago on some transmitters I was powering from a junction box. I moved the junction box about 20ft to get it outside the Class I, Div 2 area. I realize this probably isn't a solution for you.
Another time I installed the Z-purge option, of course this requires an alarm in the control room.
An explosion proof junction box is expensive and too many bolts to remove to open. I can't recommend this.
As far as removing power. All the pressure, flow, temperature transmitter we install today are rated Class I, Div I. If anyone goes to work on any of them they are suppose to have operations snif the area or diconnect the power in the control room before any wires in the field. This is because of the arc created when connecting and disconnecting. You might want to ask around and find out how many maintenance people do this.
Mark