Wall meter to measure power usage?

[eprosenx]

I have two 14awg THHN conductors going back to the pugs on the disconnect. The CT sits in the lower center box and is connected to the meter with 22awg wire.

Sorry, to clarify: You have both the 4awg and the 14 awg wires both under the terminals on the disconnect switch?

I am guessing they are not rated for that (too easy to crush the smaller diameter wire or to not put enough force on the larger gauge wire)?

Neat install!

 

[ai4px]

You cannot have two wires under one screw. What I did for my meter was to splay apart the #8 wire strands and weave a much smaller #18 wire through the larger strands. Twist 'em back together and snug up. Another option is to nick the insulation and solder the smaller wire for the meter power and cover with heat shrink.

 

[SDRick]

You cannot have two wires under one screw. What I did for my meter was to splay apart the #8 wire strands and weave a much smaller #18 wire through the larger strands. Twist 'em back together and snug up. Another option is to nick the insulation and solder the smaller wire for the meter power and cover with heat shrink.

Are either of the methods you described allowed by code?

 

[ai4px]

Are either of the methods you described allowed by code?

Nope... they aren't. Neither is two wires under one screw.... but mine is safer. YMMV.

 

[brkaus]

Probably the most "code approved" approach would be to replace the blade disconnect with a small breaker panel.

The blade disconnect is rated to 60a, that would also have to be replaced if increasing the amps of the HPWC.

Edit to add - love the look of the meter panel and the installation!

 

[Lasairfion]

At 24:23 one of the viewer contributor stories is about how to monitor your home energy usage.

 

[Amp3d]

You cannot have two wires under one screw. What I did for my meter was to splay apart the #8 wire strands and weave a much smaller #18 wire through the larger strands. Twist 'em back together and snug up. Another option is to nick the insulation and solder the smaller wire for the meter power and cover with heat shrink.

I did the weave thing. But now that I think more about it, irrespective of how it’s connected, that 14awg run is not sufficiently protected from an over current condition because the only protection device is the 60 amp breaker.

Probably the most "code approved" approach would be to replace the blade disconnect with a small breaker panel.

The blade disconnect is rated to 60a, that would also have to be replaced if increasing the amps of the HPWC.

Edit to add - love the look of the meter panel and the installation!

This is how I need to do it. That way I can put a 15 amp breaker on the 14 awg and it will be sufficiently protected.

Should be an easy change to make.

 

[eprosenx]

I did the weave thing. But now that I think more about it, irrespective of how it’s connected, that 14awg run is not sufficiently protected from an over current condition because the only protection device is the 60 amp breaker.



This is how I need to do it. That way I can put a 15 amp breaker on the 14 awg and it will be sufficiently protected.

Should be an easy change to make.

Yeah, I have never heard of the weave thing, so I am guessing it is not allowed. Split bolts may be the proper way to go.

I am not sure about the small conductor size to the meter. There are rules about “tap” conductors like off large busses and such. You can use smaller gauge wires as long as the disconnect / overcurrent device is within a certain distance of the tap. Though in this case it may not count since you have no overcurrent device for that meter.

I really don’t know...

Though I suspect that meter is not UL rated either...

 

[israndy]

Cannot you just protect the meter with a small fuse? What are split bolts?

-Randy

 

[eprosenx]

Cannot you just protect the meter with a small fuse? What are split bolts?

-Randy

Yeah, I really don't know what the rules are for this kind of setup, but a small fuse/breaker would seem logical. Obviously the previously mentioned small panel with different circuit breakers for the HPWC and the meter would be totally fine.

Here is a split bolt example:
BLACKBURN Split-Bolt Connector, Bronze Alloy, Min. Tap Conductor w/1 Max. Main (AWG) 14 sol - 3LN31|9H - Grainger

I do *not* know what the rules are on using it to link dissimilar size wires. Obviously you have to wrap the crud out of it in electrical tape. (there is also special 3M mastic tape for this application as well I think - there are YouTube videos from 3M I think).

I am really beyond my level of understanding the NEC code here on this topic. ;-)

 

[TromboneKenny]

Following because I too am looking for how to wire a PZEM-061 into a NEMA 14-50 outlet safely and passes inspection.

FYI, I tested the meter back on itself just to see it's draw and it's very small (.05A -- photo included if the forum will let me).

That's why you can get away with such small wires into the meter. As long as they're rated for 300V, the cable gauge isn't a concern for me. It's just figuring out how to tap into the two hot legs (6 gauge THHN in my case).

I haven't found a wire nut I like for 2 #6 and 1 #18 but that's probably the easiest case.

Split bolts could work but that's still multiple wires under a screw, right? And this one needs to be wrapped and just floats in the junction box.

A distribution block like McMaster-Carr looks promising. I'm going to ask at the supply shop what they'd recommend and I'll share back with the group.

 

[brkaus]

I was thinking about using this as the local disconnect.


Square D QO 100 Amp 6-Space 12-Circuit Indoor Main Lug Load Center with Surface Mount Cover-QO612L100SCP - The Home Depot

 

[Amp3d]

I picked up a small 6 space subpanel. Waiting on a top cap with the right size conduit fitting to be delivered because Lowe’s only had huge sizes but this should work pretty easily. 60 amp breaker for the charger, 15 amp for the meter. No issue with multiple wires under a screw and protects that 14 awg run adequately from shorts. And I won’t have to rerun any conduit because the knockouts are in similar positions.

 

[TromboneKenny]

I picked up a small 6 space subpanel. Waiting on a top cap with the right size conduit fitting to be delivered because Lowe’s only had huge sizes but this should work pretty easily. 60 amp breaker for the charger, 15 amp for the meter. No issue with multiple wires under a screw and protects that 14 awg run adequately from shorts. And I won’t have to rerun any conduit because the knockouts are in similar positions.

The only thing I don't like about that scenario is the cost, since you need the subpanel, more breakers, etc. for what should be a simple tap. (I understand you already had the disconnect, which changes things, but I'm trying to make this work in a junction box.)

You're going to want to wire the meter on 240V to get the math right, so look for a small two pole breaker.

 

[brkaus]

The only thing I don't like about that scenario is the cost, since you need the subpanel, more breakers, etc. for what should be a simple tap. (I understand you already had the disconnect, which changes things, but I'm trying to make this work in a junction box.)

You're going to want to wire the meter on 240V to get the math right, so look for a small two pole breaker.

IF one wants a disconnect, a small panel with a large breaker is less expensive than the disconnects I have found. The inexpensive blade type HVAC disconnects are all limited to 60A from my research.

 

[ai4px]

I did the weave thing. But now that I think more about it, irrespective of how it’s connected, that 14awg run is not sufficiently protected from an over current condition because the only protection device is the 60 amp breaker.



This is how I need to do it. That way I can put a 15 amp breaker on the 14 awg and it will be sufficiently protected.

Should be an easy change to make.

You can always put an inline fuse holder on the smaller cable.

 

[SDRick]

An in-line fuse would certainly work. There are plenty of ways to make it work. The question is are which of these methods up to code and which are not?

 

[CleanPower]

Can I connect a power usage meter like kill-a-watt or something to measure power consumed at the plug point and provide an easy readout? I will be charging at my parents house occasionally and would like them to keep track of how much power I’m using off their utilities so I can compensate them accordingly and put them at peace that the car is not gong to cost a ton of $$$ to charge every time I visit. Is it ok to plug the UMC through such a contraption every now and then?

Here is the setup I installed to monitor my electricity usage.
The meter socket cost about $35 and the refurbished meter about $25.
Ability to track my new Model 3's electricity usage - priceless!

 

[SDRick]

clean power,

Nice set up!
What size conductors did you use and did you find it difficult to insert the conductors into the HPWC terminals utilizing the concealed wire approach?

 

[eprosenx]

Here is the setup I installed to monitor my electricity usage.
The meter socket cost about $35 and the refurbished meter about $25.
Ability to track my new Model 3's electricity usage - priceless!

Nice!

Question: Why not use the wall connector as the hanger for the cable itself? (obviously the closeness to the meter base as mounted would make that an issue)

It seems like mounting the wall connector up higher reduces the overall reach of the cable if you needed to drag the cable further to connect to a visitors car, etc...