Adding a bigger panel for a new house.

[stj]

Re: Adding a bigger panel for a new house.

rules for domestic and comercial wiring in *most* of Europe is very strict.
under-rated cable just does not happen.

of course with your half-ass'ed voltage, you need a lot more copper - so your wire costs are almost double!

[diif]

Re: Adding a bigger panel for a new house.

I believe an RCD would detect the drop in current and trip, cutting off the power.

[stj]

Re: Adding a bigger panel for a new house.

on a ring you mean - i dont think so.
they only trip on an imbalance between live and neutral caused usually by a leak to ground.

[kaboom]

Re: Adding a bigger panel for a new house.

Kaboom The problem the I have with the middle picture is it is a pain to undue and to some point you are creating a magnetic field. And I suppose if one is a moose one could twist the wire nuts to a point of over tightening.

No it isn't. Let's take three blacks, one hot coming in, two going out.

First black, coming in, going up twist into wirenut: 10A
Second black, going down twist away from wirenut: 2A
Third black wire, also going down the twist and away: 8A

The sum of the currents leaving the splice, "down" the twist, is the same as the current entering the splice "up" the twist. The fields cancel and there is no inductive heating.

This actually happens in all power cords. An example is common lamp/zip cord.

What you don't want is to bring hots out of one KO in a metal box, while bringing neutrals back in another. That will create inductive heating. Running current carrying conductors seperately thru the box means their fields cross the box, which forms a shorted turn just like in a transformer. The effect isn't as great since the coupling is lower, but was a problem when extending knob&tube wiring.

One tube with the hot went into the box, another thru another hole carried the neutral. You can only do this if you cut a "slot" between the holes- this "opens" that shorted turn.

But for wirenuts/splices, the net field is zero because the fields cancel. It's an example of twisted pairs in action.

Get an clamp-on AC ammeter, which reads the surrounding magnetic field. Make up an "overtwisted" wirenutted splice and load it up. Put the "amp clamp" around the "rope" underneath the wirenut... It won't read anything no matter how much that splice is carrying.

Neither will that amp clamp read if simply clamped around a power cord; the fields of adjacent conductors cancel if the current sums and is in opposing directions. Hence the "cord splitters" that are used with clampmeters:

[kaboom]

Re: Adding a bigger panel for a new house.

of course with your half-ass'ed voltage, you need a lot more copper - so your wire costs are almost double!

Funny... Isn't that why primary voltages are so high?

Isn't secondary-level distribution, with 750mcm+ at 416/240V from a huge transformer common in Europe? Like a centrally-located, multi MVA unit feeding several/many blocks.

And you'll need triple cross section in the sec neutral from the "triplens" that result from all the rectifier-input supplies common in electronics- either that or "mandatory" power factor correction.

At least here, stepdown transformers can be fed phase-phase to keep harmonics off the pri neutral, or delta-fed (if three phase) to "circulate" triplens in the trans primary. The trans sec neutral will still see triplens back from the load, but they don't "propagate" back to the primary.

And, yes, you get "delta backfeed" if one primary phase is lost upstream of the 3-o delta-primary transformer when single-phase transformers are present downstream of the same.

[dmill89]

Re: Adding a bigger panel for a new house.

I thought taping the receptacle was considered amature. Is that not true? A person on an electrical DIY blog once told me this. I was under the impression he was a "professional".

It probably isn't necessary (especially in plastic boxes), but certainly doesn't hurt (especially in metal boxes), in a single outlet metal box there isn't much clearance between the side of the outlet/terminals and the box, and isn't hard to contact the box and short to ground when the screws aren't fully tightened (granted you should make sure all the screws are tight before turning the power back on, but I'll admit I've turned the breaker back on to test the new outlet before tightening everything up and putting the cover on a few times). As for being "amature" I've seen some electricians do this, but most don't (just as most don't tape wire nuts), likely more to save a few seconds an a cent or two worth of tape than anything else.

[dmill89]

Re: Adding a bigger panel for a new house.

So one can see the incorrect way of putting wire nuts on the above wires.

Note: the pics were just what I came up with quickly from an image search of what wire nuts are and how they were used for those outside of the US who may not be familiar with them and were not intended to be an example of the "correct" use/installation of wire nuts.

[Spork Schivago]

Re: Adding a bigger panel for a new house.

So one can see the incorrect way of putting wire nuts on the above wires. Twisting the wires around and around each other is not what one wants to do. The one with the yellow wire nut with tape is how the final look is suppose to be. This is done by stripping the wire first to length that can then be twisted with a pair of Klein Linesman pliers and only the bare ends should be twisted. One can hold the wires by the insulation when the wires are twisted on the bare ends. If the end result is to long to fit in the plastic housing then using the Klein pliers cutting edge and cut the extra off. The wires should be twisted around each other a least two full turns best is three turns. Very tightly done. Then the wire nut is screwed on to the wire and the threads of the wire nut will cut into the wire and tighten as you hold the insulation of the wires near the wire nut You tighten to a point that one can not tighten anymore without causing the insulating wires to twist while holding the insulting wires with your other hand.

When I was looking at the pic this time around, I just noticed the same thing, that the wires were twisted incorrectly. I wonder if the person had just read how to properly use wire nuts but didn't have any real experience or training and then misunderstood the directions and took a picture to show everyone how to improperly use a wirenut (thinking they were properly using them). I've always done it the way you're talking about. Just gotta make sure you twist the wires the right way so when you twist on the nut, it tightens the twisted wire even more. You'll know if you did it properly, because when done properly, the wirenut will stop twisting after a bit.

[kaboom]

Re: Adding a bigger panel for a new house.

It probably isn't necessary (especially in plastic boxes), but certainly doesn't hurt (especially in metal boxes), in a single outlet metal box there isn't much clearance between the side of the outlet/terminals and the box,

Like in a sectional device (GEM) box with madison bars/f straps/battleship clips and a GFCI? Don't ask... PVC box with "swing wings" for $50, Alex.

[Spork Schivago]

Re: Adding a bigger panel for a new house.

I've had wires twist outside the wirenut like in the middle pic (not to that degree), but that can work in your favor when pushing them back into the box. The main thing is to have the bare ends twisted together first, then tighten the wirenut onto it. The "pre" twisting is the actual splice; tightening the wirenut "preloads" the splice, as you're actually tensioning the spring inside- the wirenut "keeps" the splice together.

When you've "run out" of spring when tightening the wirenut onto the wires, and overtwist the wires outside the wirenut, you are not further tensioning the spring; at this point, you're no longer tightening the actual splice.

If you really get carried away, you'll break one or more wires off inside the wirenut. At this point, since they're all twisted together outside the nut, you can't pull to see if they're tight; load up that broken-off-inside wire and watch it heat up...

That taped yellow with three black wires doesn't look "pretwisted." See how each wire comes out at a different angle? Not casting aspersions, but every non-twisted bunch I've taken apart looked that way.

The internal spring isn't there to "dig into" the wires and carry current, it's typically steel (poor conductor) and of little cross section; the splice should be what carries current. Again, the wirenut is just a "keeper" and insulation.

I didn't know that last part there, thanks for sharing! I also think you got a keen eye. I didn't notice the wire nut problem. You've obviously got a lot of experience I'd think.

[kaboom]

Re: Adding a bigger panel for a new house.

I didn't know that last part there, thanks for sharing! I also think you got a keen eye. I didn't notice the wire nut problem. You've obviously got a lot of experience I'd think.

Thanks, but it's not as much as you think... I only try to pay attention, but end up remembering all too well. "Photographic memory."

I at least make attempts to take pride in my work.

Look at this beauty from a "repair" I un-repaired:

These were thermostat wires to a condensing unit. This was in a cutesy "retirement community" where older folks have idiot "landscapers" wreck their units. This unit was two inches into the ground (plastic pad settled, ground not prepped beneath unit/pad). Moot, since Hack-n-Slash Landscape got the coil pretty well over the years. At the end of last summer, they broke the stat wires to the unit/contactor. Some jerk told the old lady's son that "repairs will be made and the stat wire sleeved." That was last fall- I told them to have me look anyway, since the hired help doesn't give a shit...

Fast forward to a month or two ago. The son is getting the house ready to sell and wants AC to keep cool while painting. Sure enough, unit doesn't run, and it was time for me to look at it.

Here's what I found. Horrible, non-pretwisted splices, unsleeved a few inches off the ground. Keep in mind winter had passed by now, and those things got all manner of snow and rain soaked by this time.

Wire was damaged in several places- had to cut all the way back to chase where it came out and splice on good wire, and sleeve it. Used some 3/8 OD "NyCoil" tubing.

Also found jumped-out rollout switch in furnace inside. Some jackass was inside "cleaning" the unit, and because pride in your work is verboten around here, a terminal got hit and broken off. Rather than replace the ROS (schematic showed all three in series), idiot removed the jumper, connecting #2 and #3 together! You never bypass/remove safety controls on a gas appliance!

How many other units were like this? What a crime...

Anyway, first pic is splice-as-discovered. Notice broken insulation where "landscaper's friend" stripped outer jacket. See, they used invisible sleeving on the wires...



Second pic is coming out of the 2-1/2 chase/pipe under the crawlspace- they got the wires there, too.


Third is under the wirenuts. Nice and green, and nasty... No 24V contactor coil for you. Look close- one's sort of pretwisted, the other's not. And the other wire is half-on and half-off the insulation!



Repaired, my ass... Good thing they didn't damage the 240V feed to the unit and "repair" that; they'd have burned the place down.


No after pics- had to clean unit, examine furnace and get rolling. But I've heard unit's been fine since. There was a flattened section of fins on the coil, but no fin comb in the world will fix that...

I was able to save the rollout switch. Setpoint on this one was only 140 degrees F, and there was a little "tab" of the terminal left. Could I solder it? Let's find out. It was brass and a flux pen and jumper wire saved the part. Verified to trip also. Put that back and furnace worked.

Also had to rewire thermostat- someone didn't want someone else moving the fan switch from "auto" to "on" and disconnected the "G" control wire. Didn't know this at first, thought "G" was shorted to something else, had to ring it out first, then put it back. And let's not forget remove the dam in the ductwork- aka "allergen filter." Went back with plain fiberglass one and got plenty of airflow- keeping evap coil nicely loaded for central AC and furnace heat exchanger at more reasonable temps.

Poor return/restrictive filters lead to cracked HXes. Hot air furnaces don't cycle on hi-limit like boilers do!

[Spork Schivago]

Re: Adding a bigger panel for a new house.

It probably isn't necessary (especially in plastic boxes), but certainly doesn't hurt (especially in metal boxes), in a single outlet metal box there isn't much clearance between the side of the outlet/terminals and the box, and isn't hard to contact the box and short to ground when the screws aren't fully tightened (granted you should make sure all the screws are tight before turning the power back on, but I'll admit I've turned the breaker back on to test the new outlet before tightening everything up and putting the cover on a few times). As for being "amature" I've seen some electricians do this, but most don't (just as most don't tape wire nuts), likely more to save a few seconds an a cent or two worth of tape than anything else.

Okay, thanks for sharing. The only people I've seen say anything against it always say it's considered "amature". I didn't really understand why and then I started thinking. Well, if it's plastic box, maybe that's why they're saying it? Someone doesn't understand the plastic isn't going to conduct electricity. But no, if a wire came lose in there, it could still ground out to other stuff if it wasn't taped. And if someone ever removed the cover, I guess without the tape, they could probably touch a hot screw. I doubt that ever really happens. Usually people who take those covers off know what they're doing, you know?

[keeney123]

Re: Adding a bigger panel for a new house.

No it isn't. Let's take three blacks, one hot coming in, two going out.

First black, coming in, going up twist into wirenut: 10A
Second black, going down twist away from wirenut: 2A
Third black wire, also going down the twist and away: 8A

The sum of the currents leaving the splice, "down" the twist, is the same as the current entering the splice "up" the twist. The fields cancel and there is no inductive heating.

This actually happens in all power cords. An example is common lamp/zip cord.

What you don't want is to bring hots out of one KO in a metal box, while bringing neutrals back in another. That will create inductive heating. Running current carrying conductors seperately thru the box means their fields cross the box, which forms a shorted turn just like in a transformer. The effect isn't as great since the coupling is lower, but was a problem when extending knob&tube wiring.

One tube with the hot went into the box, another thru another hole carried the neutral. You can only do this if you cut a "slot" between the holes- this "opens" that shorted turn.

But for wirenuts/splices, the net field is zero because the fields cancel. It's an example of twisted pairs in action.

Get an clamp-on AC ammeter, which reads the surrounding magnetic field. Make up an "overtwisted" wirenutted splice and load it up. Put the "amp clamp" around the "rope" underneath the wirenut... It won't read anything no matter how much that splice is carrying.

Neither will that amp clamp read if simply clamped around a power cord; the fields of adjacent conductors cancel if the current sums and is in opposing directions. Hence the "cord splitters" that are used with clampmeters:

I was in error here I did not think of one coming in and going out as the fields would cancel.

[Spork Schivago]

Re: Adding a bigger panel for a new house.

What about Wago Lever Nuts? Has anyone used these before? If so, how do you think they compare to actual wire nuts? Better, worse, the same?

http://toolguyd.com/blog/wp-content/...r-Nuts-222.jpg