current sensing

[jinglis]

I would like to monitor the current on an 8 gauge wire (one leg of a 120/240 volt feed) and I have no idea how to go about it or what is on the market to make this a simple task. I would like this current to trip a relay or two relays at two different settings ( 5 amps and 25 amps ). Any ideas.

 

[iwire]

You could use two current sensing relays on the same line each set with it's own trip point.

This one runs on 240, provides contacts but is only adjustable from 2 to 20 amps. However with a little searching I bet one with a 25 amp trip point could be found.

 

[iwire]

Here is one that claims sensing from 10 mA through 60 Amps.

 

[jinglis]

If this unit is rated from 2-20 amps and I put a draw of 40 amps through the coil will it cause damage?

 

[GeorgeB]

You could use two current sensing relays on the same line each set with it's own trip point.

(image and link deleted by gbynum)

This one runs on 240, provides contacts but is only adjustable from 2 to 20 amps. However with a little searching I bet one with a 25 amp trip point could be found.

following your link, then to the manufacturer's site, I find http://www.ssac.com/catalog/ECS01A01.pdf where many options exist ... including a 5-50 range.

Re the followup question on more current than ratings ... the electronics would probably saturate and do ok; the CT would probably overheat. IF you really need that Grainger stocked unit, 2 parallel conductors with a little intentional resistance to force load sharing should do with one through the ct, one not.