CT inductive clamps and placement


I don’t have my breaker panel put back together yet as I had other work to do while in there so I’m hoping somebody has some insight to help me decide on the permanent clamp placement. I’ve e attached a screenshot of how my wires come in the bottom of the panel and they both travel together up the left side and when they get to the top, they run 90 degrees to stab into the lugs. As you can see the electrician didn’t do a very nice job (the reason I have other work to do I think here) and was tight with the wire, it barely reaches the lugs. My concern is how close together the clamps are. I have enough room at the top to put one clamp on and thought about leaving one low and the other high for a distance between them. Does anyone think this will help or hurt? With the excellent detection I’ve had should I leave it as-is?
I do have a multimeter that has inductive clamps like this and I’ve never noticed any problems or crossover when I’ve used them in tight places but it’s just for a few seconds and not permanent.
What would you do?


I’d leave them as-is… they’re working… no point to change it and there’s plenty of room…

I show my setup in this post: Let's see your setup

when I did this, I moved my wires/CTs for better routing & added a whole house surge protector… well, even though I was careful and thought I put it all back together the way I had it, it screwed up my readings, started giving me a bunch of negative numbers… by the time I got support involved, I’d built up so much negative data that I was forced to reset my data and start over… as I’ve said elsewhere, it worked out better in the long run, but I created my own mess and wasted a lot of time… so I’d leave it…


@Dcdyer saw slightly more accurate Sense results vs. utility meter data with the CTs absolutely perpendicular to the mains.

“At the same time I reworked my CT clamp installation. I used the foam insulation from a ½-inch pipe insulation as a spacer to center my clamps and to position them so that they are 90-degrees perpendicular to the service cable in the breaker panel. When I initially installed the CT clamps (Sept. 2017) they were not at a true perpendicular angle or perfectly centered around the cable. I also taped the CT clamps in closed position, making certain they were completely closed. The new foam insulation ‘spacers’ were not allowing the clamps to remain closed.”


@samwooly1 Here is a breaker panel that I recently installed. It does not have the SENSE unit installed. I do not know the electrical codes for your area, but if you want to pass city inspection in our area, the panel needs to wired neatly and follow the NEC code book. I see that you are using Square D products. I am a fan of Square D.

  1. Any white wire that is used as a service ‘hot’ must be marked with either black or red tape to indicate that is being used to carry load and is not a neutral. I think you have done that but the markings are not near the termination point.

  2. You are not allowed to double lug wires on these breaker terminations. Only 1 wire per screw point. The better option is to use a wire nut and make up the multiple connections by twisting multiple wires together.

  3. Service wires coming from the power company’s meter need to be marked: White for neutral, green for ground, black for hot, red for hot. Placing a red marker is not code but a courtesy to the next electrician who opens the panel. Also I don’t know why, but the red always goes on the right. It’s a tradition.

  4. Consider installing a “Whole House” Surge Protector. You can see the one mounted in the top right position. It is as close to the neutral bar with the shortest smoothest path possible. It case of a lightning strike or an electrical surge you want to dump that overload as quickly as you can. This is a cheaper surge protector, but it’s more than most homes have. It will protect the microwave, oven, washer, dishwasher, etc. Continue to place local surge protectors at your TV’s, computers, etc. for a secondary fall-back.

  5. When this house was built, NEC code only required AFCI (Arc Fault Circuit Interrupter) breakers in the bedroom circuits only. You can see the 3 AFCI breakers on the lower right hand side. (Green buttons) The new code requires a CAFI (Combination Arc Fault Interrupter) on all living areas. CAFI breakers test for a ‘series’ and a ‘parallel’ fault. (Yes, they are expensive!) My next install in 2019 will have mostly all CAFI breakers.

  6. Outside circuits require a GFCI breaker. You can see that breaker mounted 4th from the bottom. (Yellow button). You can also place individual GFCI receptacles at each location instead of using an individual breaker. You need GFCI for any outlet that is within 6-ft of a water source. Mainly bathrooms and kitchens.

  7. As @Kevin1 pointed out, I mounted my home SENSE unit, took readings, then later went back and re-worked my installation. My readings agreed more with the power company’s after I reset the clamps at 90-degrees and centered the clamps around the service wire.

  8. Invest in some plastic zip ties. They are cheap and will help make your installation neater.

  9. The city inspector in our area wants to see all grounds (copper) on one bus bar and all neutrals (white wires) on the other bus bar. Now the two bus bars are joined together so functionally it’s the same bus bar, but that’s his requirement. Once again, you are not allowed to place two wires terminations under the same lug.

  10. This panel is mounted on the outside of the house. The picture was taken before the siding was applied. We place a ‘drip leg’ in the wire just before terminating the wire on the breaker. We have high humidity in our area and any condensation that occurs on the wire will run away from the breaker.

Hope this helps. Provide more pictures. We all appreciate seeing other installations and gaining knowledge from other installs.


Very nice work!
Looks very clean. Ill get mine looking more like that here soon.
You noticed I double tapped the water heater breaker for the Sense, good eye!
That is temporary as I didn’t have one here and want to find the lowest amperage
available (probably 20). Since I’m doing other work then I’d prefer to have a plan so
I’m making only one trip to the supply house.
I’m also a fan of square D but Cutler was here when I got here.
I did install floor heat under tile in wifes bathroom and had a square d breaker
that I used. Its not right and I know it so its getting replaced with the correct BR style
Eaton. That one has actually given me trouble and I suspect its from using that breaker.
Ha d a relative that did his new panel after house burnt with thos combination breakers,
I couldn’t believe how much was spent.
Thanks for the response and sorry for addressing everything by jumping around, busy day

The codes in your area pretty much match what we have here. The arc faults weren’t
required when this one was built in 2000 but are now (only bedrooms). Im already in the
panel so ill just take care of it now.
How are you getting ground from the power company? We supply grund with 2
8 foot solid copper rods placed within a few feet of the meter.
I had thought of adding GFCI breakers but if I do that then Ill be removing the
GFCI outlets, Ive seen problems when the receptacle has been left in place.

We have the same thing with neutrals on one bar and ground on the opposite but
it makes you wonder because we are also required to bond.


For your SENSE installation you only need a 2-pole 15-amp breaker. You can have a larger breaker, but it’s not required.

Grounding - Goes from the neutral bar to a ground rod (if the breaker panel is the first point of connection). Old code was one 8-foot copper rod, but new code suggests 2 rods spaced 6-foot or greater apart with 1 continuous ground wire (No cuts or splices in the ground wire.) The reason is that in some areas there was not enough moisture in the ground (soil) to give sufficient grounding. The rods are only $13/ea at Lowes. We use #2 THHN for our ground wire.

GFCI - If you already have a GFCI outlet, then do not place a GFCI breaker in the same circuit. The two will ‘fight’ each other. Only one device is required. The GFCI breaker is cheaper, if you have multiple receptacles on the same circuit (like exterior yard plugs). Don’t change your setup.

Neutrals and Grounds are always ‘bonded’ in the breaker panel (If it’s the main panel). Not true if it’s a subpanel.

Eaton sells a whole house surge protector that I prefer. You can mount it anywhere inside the panel and connect to a 2-pole breaker.

Cutler is also another good brand. Stay with your current brand.


I’ll look at the Eaton surge protector and get rid of the ones I’ve got now.
I’ve wondered if Sense has a difficult time with detection due to using
them at a receptacle and having more than one device plugged in
to one.
Th ground requirements are the same here. Before we had to have a
license here (2003), I had wired a few of the houses I had built and a
little repair work. I went to one little repair in particular that the inspector
got me to do where a homeowner had built his cabin and wired it himself.
The guy had failed several times so he referred the man to me. The only
problem I had to fix was small. The guy had bought Clad copper rods. One
he got down to proper level but the other he didn’t. He cut it off and bent it
but was a dead giveaway that it wasn’t solid. As homeowners, we are still
able to do all our own work for both electrical and plumbing on our own
I could have been “grandfathered” into a license back then but didn’t want
another license because it wasn’t my normal line of work. The grandfather
option was only open for a short time and probably should have never been
A 2 pole 15 I have to order but I wanted to see if I could find one smaller. At 15 that

is more than it needs and wouldn’t really offer any protection being that oversized.
Would never be an issue but technically incorrect.


You can have multiple surge protectors. I actually have two whole house units installed. One in my main panel and 1 in my subpanel. Surge protectors are designed to fail. It’s what you want to have happen. It’s cheaper to replace a surge protector versus an electric oven. How long before they fail is determined by the number of times they have been stressed. Having multiple units is good. You also want to have an additional local surge protector anywhere you have a TV, computer, etc. Surge protectors do not cause SENSE any problems. They only work when there is a voltage overload.

The 15-amp breaker just allows you a way to connect the SENSE unit and is available if you need to turn off the power for a reboot of the SENSE monitor. You will never pull 15 amps on the SENSE monitor (so any size could work). It’s the same idea as if you plug in a low wattage LED light into a 20-amp house circuit. The LED light will never draw a full 20 amps.


Eaton has 2 whole house surge protectors. One goes right in the box
and takes up a double pole space. It has to be in the top slot is the
only thing. Very cheap at less than $70.Thats the one I think we will
get. Ill just have to make sure whatever gets moved is placed back on the
same legs.
I did end up moving one of my clamps further away early this morning.
Don’t think it made more the microwave detection I got shortly after
but It will look cleaner. I am mounting the Sense permanently outside
the panel. Ease of access if there is a problem with the monitor, not having
to use an antenna extension and plain personal preference are the reasons.