Electrical – ACS712 for high voltage

achigh voltage

Is is possible to link an ACS712(http://www.alldatasheet.com/datasheet-pdf/pdf/168326/ALLEGRO/ACS712.html) module to a 220V electrical socket? I can't say if the module is built for low or high voltage.(I'm not an electrical engineer)

If no, what I should use instead?

I need it for measuring the power consumed using an MCP3008 interfaced with a Raspberry Pi.

Thank you!

Best Answer

The ACS712 IC has 2100V isolation from the current sense side to the output side. This is completely adequate for isolation of 220v mains from low voltage MCUs and the like, as long as you maintain at least 3mm separation for all parts of your wiring.

When mounted on a PCB, this chip should have at least 3mm space between all input conductors, and all output conductors, on both sides of the board. Any less than this and the excellent isolation of the chip is compromised by the board.

There are many breakout boards available using this chip. Many of them are inadequate for mains isolation, however some might be OK. Where the isolation has been compromised, it's usually as a result of a 'copper pour' on one or both surfaces of the board, reducing the clearances between input and output to a few thou.

One bad board is the SparkFun BOB-08882. To their credit, it does say in their blurb for the product that the PCB the chip is mounted on is not rated for high voltage use. Do not use this board with more than 40v on the input. There is so much copper in the board it would not be practical to try to remove it with a scalpel.

On eBay, a quick search showed up at least 5 different boards available. Three of these were definitely bad, with a copper pour visible on at least the top surface, which reduced input to output separation to a few thou. This provides no safety protection at all, so is only good to 40v.

One board on eBay looked OK, no copper visible top or bottom. One looked OK on the top, but the bottom was not visible. At these prices, it might be worth buying one of each just to check. You might try contacting the seller before buying one of these boards, but I doubt the technical competence of most retailers.