Clamp type power monitor

lohr500

I've searched the forum for an answer, but didn't find anything suitable. 

I'm looking for a clamp type power monitor that I can use on individual devices that are hard wired and where I can't use my plug in Tapo unit.

One post suggested a PZEM-022, but I don't like the way the mains voltage connection is set up due to the exposed wiring. It looks very dangerous unless mounted in some form of extra case.

https://www.ebay.co.uk/itm/385732512595

Does anyone have or know of something similar that would be suitable for monitoring the usage on a single appliance? Ideally something that monitors usage over time, rather than just an instantaneous reading.

Thanks

QrizB

You might already know this, but be aware that you can't put a current clamp around a twin-and-earth cable and expect to get a power reading. Physics doesn't work that way.

You'll need to split out a single live (or neutral) conductor and put the clamp around that.

With that said, something like a Current Cost CC128 would work for you. They're obsolete but still appear quite frequently on eBay. Some come with USB cables that let you save data to a PC.

http://www.currentcost.com/product-cc128.html

I use one to monitor my solar PV generation.

lohr500

Thanks for the heads up QrizB. I hadn't realised that which probably explains why I couldn't find what I was looking for!!!

Gerry1

Unless you need high accuracy, a simple clamp-on energy monitor should suffice.  It will assume the mains voltage rather than measure it, but it avoids the need for exposed connections.

If you're only using it to compare usage by various appliances then the exact mains voltage won't really matter unless it varies dramatically.

QrizB

On my laptop now, not my phone, so here are a few example eBay listings:

• BG branded CC128: https://www.ebay.co.uk/itm/314677799915
• Current Cost branded CC128: https://www.ebay.co.uk/itm/225631597713
  

I can't see the USB cable in the photos of those two. This one does show it:

• Current Cost branded EnviR: https://www.ebay.co.uk/itm/175640552374

Or you can buy the cable separately. It's quite expensive for a serial-to-USB adapter, and if you're handy with a soldering iron you could probably make one for a third of the price:

• CC128-compatible USB cable: https://www.ebay.co.uk/itm/192872997079

If USB data transfer isn't important, and all you want is instantaneous & total power use, there are lots of other models starting from under £10. Here's an example:

• BG branded Trec energy monitor: https://www.ebay.co.uk/itm/314704458170
  

They were a lot cheaper a few years ago, when the energy companies would give them away as "new customer" gifts to switchers. With the roll-out of smart meters they've mostly stopped being manufactured and are becoming less common on the used market.

lohr500

Thanks both, but if I can't clamp them around twin & earth cabling, then they aren't going to help.