A little clarity for low voltage disconnect installation

DIY
1

I have bought a 40A low voltage disconnect. Here are the install instructions.

Page 4 has the wiring diagram. I am a bit confused by the ground wiring part. First the diagram shows it should be fused. Why? Second, I am used to using the same thickness cable for negative as for positive but from the tiny faston connector and that it recommends further on the same page to only use 500mA to 1A fuse max obviously they intend for the wire to be very puny.

So what is the point first of fusing on the ground wire and second for a tiny wire for the ground and not the same size as the positive, which would be above 40A capacity?

I was rushing to finish it earlier since of course all my loads on my system are off while I am working on it but then thought it better to take a step back and call it a day and wire back the lead without the LVD and ask on here rather than botch it.

2

Looks like an intelligent high side switch. The negative pin is probably ground reference and small current for the control electronics. In case of an internal control failure, it won’t be able to clear the large load fuse on pin 1 before the controls burn. Same deal with the alarm fuse on pin 4.

1 Like
3

Thanks for the explanation.

Annoying I have to order a tiny fuse now for a few pennies and pay far more for them sending it. :confused: Often happens!