I am having my electrician buddy help me replace an old circuit box in a fairly old house. Much of the wiring is old and cloth covered from the
40's. What happens if one of the wires we are replacing breaks or is too short to reach the breakers in the new panel? Do those broken wires have to be spliced with wire nuts to a new piece of wire and then the splice section mounted in a new junction box outside of the new panel? That could get ugly very quickly but my limited knowledge of the NEC says splices have to be with approved connectors and inside junction boxes.
Will he have the tools to determine if any of the wiring in the house has decayed enough to present a fire hazard? Do you measure the resistance of the wire from the panel to the eventual load? I know that one very long run to the kitchen reads 105 volts with the microwave on when the voltage at the breaker serving that run is at 119 volts. This is a run that has been used, apparently, for years with a 20A breaker even though the wire apparently is only 14 gauge. We will be correcting that by wiring it to a 15A breaker
Also, he talked about "balancing the load" within the panel. Why is that important?
This may sound like a stupid question but why are the breakers staggered? I thought the A hot coming in on the left fed all the breakers on the left and the B hot of the right fed all the breakers on the right. Apparently not. Why?
Any other pointers on panel upgrades or sites where I could learn more about the process? I've been watching a bunch of so-so YouTube videos, but they don't seem to answer the questions I have.
I've already gone through the panel and marked down which wires go where by shutting each breaker off in turn and making note of what outlets and lights were no longer powered. My buddy said that's often the worst part of a panel replacement. I assume the wires have to be properly labeled as they come off the old panel and get attached to the new one. Would a Brother label printer do the job? Would it pay to get the kind of labeling tape that's actually heat shrink tubing? Would it be code-worthy to label each wire like that permanently?
Some of the cloth covered original wiring looks awfully frayed. I am guessing that it's not code to sleeve them with plastic shrink tubing but I suspect the real fix is to replace the wire which would about quintuple the price of this job.
Would this be a good time to check the house's grounding system? How do you measure the quality of the house's ground?
I'm assuming that he's going to know all of this stuff, but I'd like to be as well-informed as I can about what problems we might be facing since I will be assisting (mostly holding the flashlight or heading out to Home Depot if we don't have everything we need).
I was also wondering if it would be prudent to place an externally mounted shutoff for the whole house between the meter and the box? As it stands now any work on the panel involves disconnecting the smart meter and a shut-off would eliminate that step.
You just apply the wirenuts inside the breaker box. That box is a (junction box) as far as the code. Of course try to get the wires to breakers that are possible to do without splicing if possible.
Unless this has changed in recent years, you CAN put heat shrink over old wires, as long as they are not bare from insulation breakdown. That old cloth covered wire was pretty durable, except if it was exposed to heat, like in boxes above enclosed light bulbs. Then it got real dry and often broke off the wire. Modern LED and CF bulbs would not be such a heat problem, but the old filament bulbs were tough on those wires.
A lot of old tube type electronics also used that cloth wire, and some had very high voltages.
Unlikely, IDK that such a tool commonly exists or is used.
You could, but don't know anyone that does that, nor is it very probative. If you have a loose/poor connection which it would show, you'd likely have seen symptoms, eg dim lights, flickering, etc. And resistance isn't going to show frayed wiring about to short, etc.
I know that one very long run
That is more than is desireable, which would be under 5%. Since that run has a large load and is suspect, I'd run a new 20A circuit.
You want to try to distribute the 120V circuits so that about half the total load is on one hot leg, half on the other. That keeps the load on the neutral down. It's always going to be unbalanced to some extent, you just don't want to put all the loads, or all the large loads, on one leg.
So that you can put in a 240V breaker, which needs to connect to both hots.
I wouldn't waste my time. Some temporary tape, then labeling the new breakers once the panel is in works for me.
Can't say how bad it is, but if it's fraying and in bad shape, I would do the re-wire because of the risk. If you don't then I'd put in AFCI for all the breakers that are on the old, suspect run.
Yes.
IDK, good question. In most cases, I think they just go with what works. For example, if you have a metal cold water line going to a well or city water, that works for me. Current code requires an additional electrode, typically a ground rod.
Work is done all the time inside the panel, replacing a breaker for example, without pulling the meter. You just shut off the main breaker, which leaves everything after it off. You just have to stay away from where the feed comes in at the top. There are new panels available that have that top section under a separate cover, eliminating even that small risk.
Is the existing feed adequate? How many amps? Any new loads, eg AC, in your future? Now is the time to make sure you have enough capacity.
That helps. This old panel's neutral wires are very, very short and I suspect it's going to be a bit problem depending on where the neutral bus is located in the new panel. He's bought that so all I can do is keep my fingers x'ed.
He was talking about having some sort of expensive analyzer tool that can reveal a number of defects in the wiring - what they were he didn't say but I am looking forward to working with him this weekend if only to pick his brain. All the YouTube videos have been helpful. I had no idea that the ground and neutral busses are aluminum and the wires entering them need to be slathered up with Noalox. The new panels I see in the videos differ a lot from what I have. One guy says to meet inspection requirement all wires going into buss bars have to go through completely so that you can see a little bit of the wire protruding through the other side of the bar.
That makes sense. Thanks. I am worried about the old wiring though and pulling new wire would be an enormous amount of work. As far as I can see, the fraying is only bad where the sheathing has been stripped back. White wires are now rather brownish-yellow.
I am beginning to suspect that's going to be what happens but right now we've run over budget with AFCI breakers going to the bedrooms and the possibility of having to install a new ground. I've added 15% to cover unexpected contingencies, but that was a rather low but hopeful estimate.
I have to confess, although I've read a lot and watched a number of videos, I'm still not very "up" on - not even sure what to call it - multiphase circuits. As in why doesn't the neutral from the pole have to be larger than either hot feed because it carries the return curent from both hots? Not necessary that I do understand since I am just a helper, but it would be nice to know.
Is that why the 240 breakers appear to be double-size - they're contacting two different places on the internal power buss?
Sounds reasonable. I want it to be neat but I realize that just a temporary label is all that's needed to land the wire in the right place in the new panel.
I did spec 4 AFCI's but for the bedrooms and that wire's ironically in the best of shape. I would have done the whole panel with AFCI's until my buddy told me what that would cost. Didn't seem worth it but I'll discuss it again. If it's that much of a safety advantage it might be worth it. I might want to try to find out how many arc fault fires there are in the US each year to gage the odds.
I've read about grounds called Ufers (one site claims that a direct lightning hit can destroy your foundation - I am assuming that's a Ufer ground built into a new home's foundation. It sounds like I would bury a Ufer close to the building. Still researching that.
Ironically the replacement is because the 100A breaker in the old panel was heat damaged. If you recall, the hot on one side had lost its Noalox and began arcing and the heat (measured at over 200F) damaged the breaker. My electrician buddy pulled the feed wire, cleaned it (no apparent heat discoloration), gooped it up with Noalox and then tightened it back down when the set screw stripped.
I've been measuring the loads with a clamp meter. Maximum load hovers at 50 to 60 amps. I assume that 200A service (what he says I have) is good enough for that kind of load. That was with everything I could think of turned on and two space heaters running at 15A each.
Thanks for all your help. Are you an electrician? You sound like one! This sort of feedback will allow me ask smarter questions of my electrician buddy.
That's up to Lady Luck at the moement. It may mean rearranging the wires from the current scheme.
The problem, other than age, was that these cloth covered wires entered the box directly above the 100A breaker that was generating a lot of heat for who knows how long because of the bad connection. The feed into the 100A breaker starting sparking - it turns out that the set screw on hot feed from meter stripped - right now my electrician friend's got it patched with a tapered piece of stranded 10 gage wire shoved into the hole to eliminate any air gaps. That's held for quite a while but it is now time to "do it right!" I guess we won't know how bad the wires really are until we disconnect them all.
The normal home in the US if fed with a 240 volt transformer with a center tap. If using only 240 volt devices such as a water heater the center tap (neutral) is not hooked up. When using the 120 volt devices you hook one wire to one of the hot wires and one to the neutral. If you have 2 lamps that each has a 100 watt lamp in them and they are on the same side of the transformer then the neutral has to carry the full current. If you hook them to eahc side of the transformer and they are execatlly equal (which will not hapen in real life,but will be close) then no current will flow in the neutral wire and you could actually do away with it. If you have a 100 watt bulb on one side and a 60 watt bulb on the other side,then there is an unballance and this curent will flow in the neutral. It would be the equal of having just one 40 watt bulb hooked up.
That is why you try to ballance the load. Maybe put the refrigerator on one side and the room with the TV on the other side. Also put say the kitchen lights on one side and the living room lights on the other side. Those are usually the two most often used lights that may be on at the same time.
The neutral doesn't carry all the current. It only carries the unbalanced portion. If you have 30A flowing on one hot, 20A on the other, the service neutral has 10A. If instead both legs have 20A, then the current in the neutral is zero.
Draw a simple circuit with two 120V batteries in series that drive two 3 ohm resistors in series. Connect the midpoint of the batteries with the midpoint of the resistors. That's essentially what you have with a balanced load. 20A is flowing, but nothing in the wire between the midpoint of the batteries and the midpoint of the resistors. Now change the resistors so one is 4 ohms, the other 2 ohms. Now the load is unbalanced and you have current flowing in the midpoint (neutral) connection.
Bingo.
I don't know what current code is on AFCI requirements, but AFAIK, it's beyond just bedrooms now. I think most living areas require it, but Gfre here can give you the correct answer. Anyplace with old, suspect wiring, I'd put them on all the circuits that have that old wiring.
I ufer is a concrete encased electrode that uses the cement pour of the building during new construction. You need a simple ground rod.
That is not exactly true. From the code... "312.8 Enclosures for Switches or Overcurrent Devices. Enclosures for switches or overcurrent devices shall not be used as junction boxes,"
It goes on to say "conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space."
That can start a fist fight at an inspector meeting about exactly how much excess space is available in a given panel. You will also hear the argument that a splice does not count at all in "wire fill".
Home inspectors are known to flag a single wire nut in a panelboard enclosure but most of them are ignorant of the actual code.
If this is being inspected, ask your AHJ what their opinion is about it. Neatness really counts here. If it looks OK, I am willing to let it go.
Most panels have several places where you can add grounding buses so that can help with the ground wires and even the neutrals if this is the service disconnect enclosure but be sure to loop a #4 wire between all of them if you are using them for the neutral since you can't use the screws into the can for neutral current. (250.6) Again I would verify that with the AHJ.
It is OK to depend on the mounting screws if you are just connecting ground wires.
Another option is to use one of these mounted near the top of the panel for your splices.
This is what makes electrical work "interesting"! (not)
Do your homework and try to reshuffle the placement of the breakers so you can attach each branch circuit to *a* breaker -- even if it is not in the same physical position as previously. Lots of attention to detail can also be a win when selecting a new panel -- to minimize the distance the wires "need" to travel to reach their corresponding breakers (don't forget about the neutral connections, as well!)
Have you considered using one or more subpanels as a "cheat"?
The "wire" (i.e., "conductor") won't degrade/decay (when copper "rusts", it forms a greenish oxide layer) but, rather, the insulation may be a problem -- especially where it may have experienced mechanical wear (like in the panel and terminal Jboxes -- lots of flexing as it is connected/reconnected)
Sure to get flagged by an inspection. For "efficiency", you typically only want a 3-5% voltage drop under load. Wire is "sized" so the heat generated in the conductor is safe for the insulation chosen (the wire won't melt but the insulation will degrade).
SERIOUSLY consider running two new 20A countertop feeds into the kitchen. Most of a home's AC is consumed in the kitchen. You'd also like to avail yourself of GFCI and AFCI protections.
[I think we have 5 or 6 circuits feeding our kitchen, not counting the oven/refrigerator/lighting]
And, chances are, you have all "two wire" circuits -- no earth/safety ground available at your loads.
The AC line feeding your residence is really two 120V lines wired one "atop" the other. Sort of like putting two 120V batteries in series:
120V 120V
+XXXXXX- +XXXXXX-
A N B
The "neutral" wire is connected to the middle -- at 0V. So, you can think of one "leg" as being +120V (i.e., at 'A') the other as being -120V (at 'B').
But, as this is AC and not DC, the 'A' point is really continuously varying ("alternating" as in "alternating current") between +120V and -120V while, at the same time, the 'B' point is alternating between -120V and +120V!
[there's a bit of a lie, here, but not one that is material to the discussion]
For a 120V appliance, it "sees" the 'A' (or 'B'!) leg alternating between
+120 and -120 with the other wire connected to neutral (0V). Thus, 120V AC! The load current flows "from" the 'A' (or 'B') to the load, through the load and then returns on the neutral. (all of the electricity flowing OUT the A -- or B -- ends up coming *back* on the neutral. A "closed loop")
For a 220V (240) appliance, it sees one leg alternating between +120 and -120 while the other leg is alternating between -120 and +120. So, there's
240V AC *across* the device -- and the neutral wire is not involved!
Because A and B are "opposites" (A is positive while B is negative and A is negative while B is positive), the "neutral current" from an appliance fed from the 'A' leg is "opposite" what the neutral current from an appliance fed from the 'B' leg; one is "going" while the other is "coming".
As you bring the loads on the 'A' and 'B' legs into balance, the neutral current from that 'A' loads cancels out the neutral current from the 'B' loads thereby reducing the current flowing in *THE* neutral (from the power company).
If you consider the "two batteries in series" example, above, you can see that the electric utility would prefer that you "load" each battery similarly; why include the second battery if folks are just going to put EVERYTHING on the first??
[The batteries are really transformers -- technically, a *single* transformer with a "tap" in the center. If you're only using one half of the transformer, then all of the heat is generated in that "winding" while the other is just taking up space, so to speak]
When you remove the panel (or, when it has had all of the breakers removed), the reason will be obvious. :> It's just easier to make it that way!
Methinks he exaggerates! :< It's just tedious, not really "bad". I prepared a scale floorplan of this house and adorned it with notations of each Jbox, circuit number, etc. just so I could KNOW where everything went. I.e., which breaker controls power to the smoke detectors??
When you are done, be sure to walk through the house and verify you have identified the breaker for EVERY outlet/switch -- to make sure you haven't missed something (which you might want to *change* in the process!)
I.e., did you remember the outlet behind the refrigerator? For the garbage disposal? Garage door opener? Front porch light? Dishwasher? etc.
Yes. Otherwise, you will have the panel disconnected (no power in your house!) while you run around trying to figure out what each wire does. Easier to do this BEFORE you turn off the power (and inconvenience the occupant)
Pro'ly. You might find it difficult to get the label tape to stick to the (cloth/asphalt) wires. As such, you might want to use a "flag" sort of attachment (wrap label around wire and adhere it to *itself*).
Note that you probably want the power off on the panel if you're going to be messing around with individual conductors. It only takes an ohnosecond to cook yourself!
No. That would require you to disconnect each wire before labeling. I.e., you'd only be doing that when you'd shut off power to the panel (and then you're back to the "inconvenience" issue, above).
No. Labels can be flammable.
Presumably, you have a basement and/or attic? I'd probably leave most of the living area outlet and lighting circuits "as is". But, would seriously consider redoing the kitchen/meal prep circuits. More capacity is usually a good investment. Even if you don't upgrade the service, you might find it convenient to be able to run an electric skillet AND the microwave at the same time (by moving them to different circuits). Or, not having to worry about tripping the breaker for the refrigerator (food spoilage) because some other appliance happened to be on at the same time, etc.
You will probably also discover that your existing wiring is not up to code (kitchens, bathrooms, garages and basements see lots of code revisions -- 70 years is a LONG TIME in code terms!). Recall that the code is there for YOUR safety, not just as an excuse to "make work" for electricians!
Here, I've considered running a new branch circuit into the bedrooms as I use one for my office (and have LOTS of electronic equipment in there; so much that I am cautious about what I turn on at any given time!)
Always a good idea as this is what keeps you safe. Of course, if everything is 2-wire, you're already bucking a headwind.
Dubious value. Unless you want to anticipate a whole-house genset in the future!
Have fun. *Plan* on things going wrong/taking longer than expected/etc.
[You might also want to carefully investigate the panel chosen -- particularly wrt the breakers! Will you be able to purchase replacements in the future when these "new ones" fail? Or, will you be scouring the used building supplies/surplus shops hoping to stumble across one that fits YOUR panel
20 years hence?]
A lot easier here in Canada where inspectors don't look ascanse at panels mounted "sideways" I was able to replace my old Consolidated? fuse panel with a new Square D QO panel without having to pull a single staple or move a single wire - and had wire to spare by simply laying the QO panel on it's side with the main to the left.
The electrician was a bit of a ditz and used the top neutral buss for circuits that were on the bottom breakers - which made foe some fun when I went to install an arc fault breaker in the bottom side of the panel because "sparky" had cut the neutral to make it a neat fit to the top buss. I called the inspector and he said no problem using a Marrette 65 to tag a length of #12 or #14 copper to the aluminum neutral to extend it to the bottom of the panel, so that's what I did.
Coulda skinned "sparky" for telling me I didn't need to upgrade to GFIs and AFCIs with the panel upgrade when I was doing it for "insurance inspection requirements" - and I asked him NUMEROUS times, just to be sure.
So I had to upgrade it all after he was done when the inspector said it was needed - meaning I needed to pull another permit and get another inspection. Thankfully the inspector was very understanding and he got me a "no charge permit and inspection"
Neighbor ran a new service a few years back (challenging as our utilities are below grade -- had to retrench to the local tap, have the trench inspected, etc.). He spent several days carefully mapping out the NEW locations of each breaker in the replacement panel to ensure every wire would "meet up with" an "appropriate" breaker in the new panel. And, was *still* sweating bricks when the time came to disconnect the old service and install the new!
[house is made of concrete block, no basement, no attic -- so what you see is ALL you're gonna get!]
I long ago learned that asking THE SAME PERSON multiple times is useless. Have to find another set of ears and hope they *agree*. And, if/when they don't, you can at least confront the first set with this "other opinion".
In my neighbor's case, he was a cop so "professional courtesy" on the part of the inspector. Lots of "visits" but I doubt he was billed for more than one (to be "on the record").
[It pays to "know someone" :>]
OTOH, didn't help him much when he snagged the gas main with his back hoe while digging the trench! Gas company didn't care *what* his day job entailed: "We got a problem, here, son..."
That's why I've only got 125 amp service - I wasn't willing to do or pay for the trenching required to go to 200.
The fact my Dad was an electrician and I knew how to do what needed to be done helped in my case. When the inspector did the initial insurance inspection he said other than needing the GFI protection installed it was one of the cleanest inspections he'd ever had. - which really helped. He wasn't the same inspector who did the service inspection, but it was the guy who did the service inspection that did the inspection on my GFI installations. I took pictures of what I did and how - when he came in I showed him the pictures and told him what I did, how and why
- and he took off one plate to take a look - and that was it.
I looked into it when the neighbor did his. Then, thought carefully about what are *actual* loads were and how we were managing them and decided that consuming *more* energy wasn't the solution!
ACbrrr is our biggest load. New windows help a bit. Replacing the unit periodically also gives us some efficiency gains.
(Electric) oven only sees use when baking. And, I tend to do that late at night (lifestyle issues) which tends to be when cooling load is lighter, anyways!
Beyond that, my "technology" is the only large, static load. And, I can easily drop that by an order of magnitude every few years. So, end up with more but consuming *less*.
Much less risk than taking on a major rewiring job!
I didn't say the efficiency aspect would get flagged. Rather, that a 14AWG conductor was fused at 20A. The efficiency note is intended to explain why the 14V drop is Not A Good Thing. The wire sizing and insulation note is to explain why a wire is sized for a particular ampacity.
It is amusing that heat is our biggest load here. A 3 ton AC will end up with 15kw of toaster wire heat, that might only be on 1 or 2 days a year. I don't think mine has been on once in 3 years but it is still in the load calc.
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