Fusing Each Power Consuming Load

[ano]

When wiring up a panel, does it make sense to add a fuse to each power consuming sensor, like motion sensors, etc.?  At first you may think, no that's crazy, but when you think about it, without fuses, if any sensor shorted, or any power wire was pinched and shorted, it would bring down your whole system.  Yes the panel has a resettable fuse, but that means every device would be in alarm.  
 
You add an EOL to the sensor wires, doesn't it make sense to also fuse each power wire? 
 
If anyone has ever done this, do you know of a small bank of say 1A fuses you can buy to do this?  Then if a power wire got shorted, it would be easy to find the offending sensor. 

 

[RAL]

If you want to fuse individual devices, or perhaps groups of devices, something like an Elk PD9 or an Altronix PD4, PD8 or PD16W would be your best bet.

 

[sda]

Not a terrible idea, but a low ROI.
 
In a dead short, you'll want the fuse to blow before the board's internal PTC kicks out.
 
You could try adapting an auto fuse block and load it 1/4A AGC fuses.  Smaller footprint than a PD board. 
 

 

[ano]

The auto fuse block is a good idea. The others are good as well, just seem so large.

 

[mdesmarais]

If you are willing to be a little more DIY, you could pretty easily make up a PTC board of your own- you can get SMD PTCs and mount them on a little piece of perf board. Then it could be pretty much as small as you can get physical connections to.

 

[drvnbysound]

I've got a 24VAC PD board that uses the 3A, ATC style fuses. Does anyone know of any drop in replacements that are PTC/resettable? I've been searching, but haven't come up with anything yet.

 

[ano]

I'm thinking each fuse would be 0.250 A max. Any higher than that and it would trip the panel fuse first, defeating its purpose.

 

[drvnbysound]

I'm thinking each fuse would be 0.250 A max. Any higher than that and it would trip the panel fuse first, defeating its purpose.

 
I am not sure I follow. The 4-channel PD came with 3A fuses for each circuit, so I have been looking for 3A PTCs that could be dropped into each ATC-type "receptacle" - basically a 1-for-1 swap between ATC fuses and PTCs.
 
My issue is that the PD is located in a difficult to access location. I've had a fuse blow previously, not sure if due to a surge, overdraw from the connected device, faulty fuse, etc... However, when I was finally able to replace the fuse, the connected device came back online and went back to a fully functioning state. Due to lack of easy access, I'd like to replace the ATC-type fuses on the PD with automatically resettable ones - so in the case like above, the equipment should come back online once the fault is resolved, without me having to access it.

 

[sda]

I have been looking for 3A PTCs that could be dropped into each ATC-type "receptacle" - basically a 1-for-1 swap between ATC fuses and PTCs.

Most ATC-PTC fuses or ATC circuit breakers are 10A or more.   Maybe you can get a PTC with leads and slip it in the ATC slot, or solder it into an ATC fuse body.

 

[ano]

I am not sure I follow. The 4-channel PD came with 3A fuses for each circuit, so I have been looking for 3A PTCs that could be dropped into each ATC-type "receptacle" - basically a 1-for-1 swap between ATC fuses and PTCs.

For cameras, 3A would be fine, but the total current output for Aux. from an Omni Pro II or ELK panel is 1A. Motion detectors and smoke alarms typically draw 25 ma or less.  If you look at the Elk PD9, each output is rated at 0.25 A for that reason. (And it does use PTC's, so they must be available at 0.25 A)  The problem is the Elk PD9 is huge.

 

[drvnbysound]

For cameras, 3A would be fine, but the total current output for Aux. from an Omni Pro II or ELK panel is 1A. Motion detectors and smoke alarms typically draw 25 ma or less.  If you look at the Elk PD9, each output is rated at 0.25 A for that reason. (And it does use PTC's, so they must be available at 0.25 A)  The problem is the Elk PD9 is huge.

 
I didn't mention anything about an Elk or OPII This is a stand-alone PD (also not Elk) connected to cameras.

 

[Del91574]

When wiring up a panel, does it make sense to add a fuse to each power consuming sensor, like motion sensors, etc.?  At first you may think, no that's crazy, but when you think about it, without fuses, if any sensor shorted, or any power wire was pinched and shorted, it would bring down your whole system.  Yes the panel has a resettable fuse, but that means every device would be in alarm.  
 
You add an EOL to the sensor wires, doesn't it make sense to also fuse each power wire? 
 
If anyone has ever done this, do you know of a small bank of say 1A fuses you can buy to do this?  Then if a power wire got shorted, it would be easy to find the offending sensor. 

Depends really on the size of your system, but if it's really a concern, once you get to the size where there's a supply, I'd just get the appropriate board in the OEM device. Altronix makes plenty of PD supplies that have 0V drop on battery and all the way up to 10A output. PTC vs. fuse is a design criteria to consider.

A fuse is an absolute disconnect and it can be a bane or triumph for service, same with a PTC.