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General Category => TED Pro Support => Topic started by: RhodyNut on March 10, 2017, 07:22:42 PM

Title: Split-core CTs and the Spyder (Noob question)
Post by: RhodyNut on March 10, 2017, 07:22:42 PM
I am looking at this solution to monitor home energy use on an existing home. It would appear that the split core CTs could be added to the home without needing to get an electrician to come and do the setup.  That said there are no lower amperage split core CTs that would seem to be available on the TED site.  However there are other CTs available from different manufacturers that are split core at the lower amperage.

What kind of options are out there to keep the installation price down for a technically savvy non-electrician that doesn't want to play in their electrical panel?

Title: Re: Split-core CTs and the Spyder (Noob question)
Post by: pfletch101 on March 10, 2017, 08:54:18 PM
The only place where you absolutely need split cores is for monitoring the utility feed coming in to the main panel where (as is the normal case) there is no user-accessible way of cutting power 'above' the point at which you want to be monitoring current flow. In this location, you also generally need the higher current-measuring capability of the regular split-core TED CTs. For measuring lower current flows in branch circuits, split cores are a "nice to have" for speed and ease of installation, but any technically savvy person should be equal to the task of turning off and detaching breakers one by one, unscrewing and removing the wire from the breaker's live terminal, threading it through an appropriate core, and reassembling everything - it is not rocket science!

I would certainly not recommend trying to use a CT not supplied by or (at least) approved by the TED folks. The CT needs to be matched to the electronics monitoring it, and the specs of the TED MTUs and CTs are not (AFAIK) published.

In any event, if you really don't want to go inside your electrical panel at all, you will need an electrician, anyway.
Title: Re: Split-core CTs and the Spyder (Noob question)
Post by: RhodyNut on March 14, 2017, 12:49:31 PM

Thank you for the information and snide remarks.  Always appreciated.

Yes I am handy enough to unscrew a few cables, slide the "donuts" on, and reassemble accordingly without too many extra parts left over.  Also, I could probably insert and attach the MTU to a new fuse.

All that said, requiring an electrician simply adds to the cost of the system.  Not sure about rates in your area, but for me it is $75 an hour.  Given that I have 2 200 amp panels and a sub panel for solar, my guess is that will increase my overall installed cost by several hundred dollars.  At least that is my laymen's perspective on the process.

If however, the MTU could be plugged into a panel outlet and split core CTs were available for a for a few extra dollars per even better.  I agree it is nice to have, but I would assume procuring the split core CTs and building a plug adapter for the MTU is easier than fixing software defects.  Not to mention making it easier to install and utilize might increase the number of customers adopting TED.

In any case, thank you for the warning about mixing and matching components due to the sensitivity of the electronics involved.

Then again, I am just a noob so what would I know...
Title: Re: Split-core CTs and the Spyder (Noob question)
Post by: pfletch101 on March 14, 2017, 01:46:46 PM
I do all my own electrical work - in a previous house I even replaced the main panel to allow the use of breakers rather than fuses - so I regard the work needed to install TED as very unchallenging. However, a serious problem with your suggested approach is that it requires low voltage wiring to go from inside the panel enclosure (where the CTs really have to be and you are apparently happy to install them) to outside the panel enclosure, where you would be installing your notional "plugin". My understanding is that this would at least potentially introduce some serious Code issues, which are avoided by keeping everything within the enclosure. I believe that this is also the reason why TED have stuck to power line data transmission between MTU and gateway/ECC, at least for their lower end systems - PLC avoids any issues about violation of the panel enclosure.
Title: Re: Split-core CTs and the Spyder (Noob question)
Post by: twwebster on April 04, 2017, 03:44:08 PM

I am not an electrician, But I know a lot of people that are, where I hit the hey is my thinking right mode is usually on wire size.

I have built my own 10K wind turbine and wired it in. I just installed my unit (1 ECC, 2 MTUs, 3rd MTU and 2 spyders in the future) took about 20 minutes last night.

You'll have no problem installing it to their instructions.