checking out a house's electrical system

[RustyShackleford]

Knowing that I'm an electrical/computer engineer who has done a fair amount of wiring on my own house, a friend has asked me to look at the electrical system in the house they just bought to "see if anything looks weird". They had a standard pre-sale inspection done, but the guy just did some pretty superficial stuff like checking that outlets were grounded and cover plates installed, and added some boiler-plate about having a licensed electrician inspect the system. There's no reason to believe anything is wrong. I'm not going to be paid, and I don't intend to assume any liability. All that being said, I'm wondering what people would suggest I do in spending an hour or so having a look. Here's what I've thought of so far:

1. Check for correct polarity and grounds using a simple circuit tester (as the pre-sale inspection did).
2. Open up a box or two and see if the wiring seems to have been done "in a workmanlike fashion".
3. Pull the cover off the load-center and see if things look kosher.
4. Turn on most of the big loads and see how much the voltage drops.
5. Note any aluminum wire.
...

TIA.

 

[Rusty18]

Depends on the age of the house. Have seen “remodels” that ran Romex out of a new panel right up the attic where it was spliced on original tube and wire. Speaking of the attic, seems to be a good spot for one feed to branch off 8 different ways and make some (attempt to) wire nut connections that have no chance of fitting in the box. Another one is multiple branches running back on one neutral (hard to identify in an hour inspection)(should have same number of neutral/ground/circuits, not a guarantee there isnt some funny business in a box down stream but it’s a good start). I have 12/4 with 3 hot 120’s and a common neutral (thank you previous owner ). since you are gonna have the cover off the panel take an amp clamp to check loads on circuits when you have everything turned on. And finally the condition of the bus bar in the panel, rotten stabs can lead to a full replacement when the rest of the panel looks good.

good luck!

 

[EbS-P]

What I wish I had done 10 years ago when the house was empty was correctly identify every outlet/fixture to its corresponding breaker. It would have identified that the kitchen remodel that was done before we bought the house had plugged the 1800w microwave as on an old circuit that had 8 other outlets and ceiling fan and lights. I and then I hope I would have found that the just used the push-in connectectors on the back of a 50 year old outlet because the screw terminals were all full. Had an intermittent m wave for a week then no m wave as it melted the wires in the push-in terminal.

bigger job than an hour but worth it I think. I does depend on how many modifications have been made to the original wiring. Mine is all over the place now. Flipping a breaker is kinda like cow plop bingo. You know you end up with some poop but your not sure where.

Evan

 

[zrock]

if i was your friend i would have told the inspector to do a proper inspection and if he was uncomfortable doing the electrical to have a licensed electrician do it... If he skimped their where else did they skimp? The inspector should have opened up the electrical panel, outlets, and climbed up into the attic and areas looking for wiring and issues... That's what you pay a inspector for.

Last home inspection i had the inspector did electrical and pointed out half the home was alum wire and a lot of poor connections.. It came down to the house was going to need a total rewire

 

[peakbagger]

Make sure the panel is not a Federal Pacific, they have known issues. Open up the panel and see if someone doubled up hots on individual beakers. The vast majority of breakers are only rated for one wire to be connected.

 

[RustyShackleford]

And finally the condition of the bus bar in the panel, rotten stabs can lead to a full replacement when the rest of the panel looks good.

Sorry @Rusty18 , but what do you mean by "rotten stabs" ?

 

[xman23]

I have a few of those "rotten stabs" They are a male blade that the circuit breaker is pushed down on. It's a spring contact. Under load it tends to arc and burn the stab. The result is blinking lights.

 

[Rusty18]

Sorry @Rusty18 , but what do you mean by "rotten stabs" ?

The part of the bus bar that sticks out and actually makes contact with the breaker.

The 3 or 4 I’ve seen in residential box’s appeared to be from crap being packed around them and holding moisture and/or providing a very low current path to ground causing that one area to corrode faster than the rest of the box (my opinion). Shows the same symptoms as a rotten conductor, browns outs under load, sometimes there’s voltage sometimes there isn’t. When they get that rotten though it will usually break off and come out stuck inside the breaker.

 

[Rusty18]

See the “stabs” sticking up down the middle?

 

[peakbagger]

Rotten stabs are usually brand specific. It can be made worse by installation practices. The panel should be mounted to a piece of plywood attached to the masonry wall behind it, preferably with spacer behind the plywood to allow air flow. Direct mounted panels on a cold masonry wall can drive moisture from the wall into the panel and it can condense on the internal components. Low grade copper or copper plating can eventually deteriorate.

 

[stoveliker]

Not an expert, but go in the attic. And stay there for a while. I found multiple pigtail connections that were not taped and not in a box. with insulation stripped so far back that I could touch live wite... And under the fiberglass batts that were in between the joists. Sparks waiting to happen. I put them all in boxes.

 

[RustyShackleford]

Thanks !

 

[begreen]

Make sure the panel is not a Federal Pacific, they have known issues.

We say that about Zinsco (Sylvania) panels locally.

While in the panel, feel each breaker for warmth. Also, check the screw tightness on each breaker and neutral connection. I was surprised at how many loose ones I have found over the years.

 

[Rusty18]

We say that about Zinsco (Sylvania) panels locally.

While in the panel, feel each breaker for warmth. Also, check the screw tightness on each breaker and neutral connection. I was surprised at how many loose ones I have found over the years.

Wadsworth too.

 

[fbelec]

also check the main breaker and the breakers below the main for water stains. if it is wet or there are water stains on the side of the breaker that faces up then those breakers and the main are junk. it would force the home owner to either replace all the circuit breakers or do a panel change. per national electrical code. then first order of business is to check out the service outside. if it is a cable to the top of the meter then make sure the top of the cable where it goes into the meter has uncracked or flexible clay or silicone

 

[peakbagger]

Panel replacements seem to be a popular issue that comes up on home inspections when people are selling homes. Rarely do older homes have clean code compliant electrical panels. 60 Amp services were popular up into the 1960s and at one point in the 80s states were trying to limit home services to 100 Amps max to reduce electric demand. I know my 200 Amp panel is running short of spaces as I have a lot of 240 volt standard size breakers taking up space. I could use the half size breakers to take up less space on the bus but that does not help with all the wiring run in the panel. Changing out a old panel is not that hard as long as the incoming capacity does not change but in most cases homeowners or code require an upgrade to higher amperage. In that case the incoming service has to be upgraded and that is above the ability of most homeowners.

I know that when I sold my parents1960s home that the panel was marginal and should have been replaced. I had several offers over asking price so I let the first buyer counter after the inspection knowing that if they came back with a long expensive list I would just call up the next person on the list. I did not get a copy of the report but the panel did not come up. Turned out they hit me up for radon removal. I gave them a discount on their original offer (still over the listing price) in exchange for them signing off for any defect known or unknown to get it over with. The market was not as hot as it is now. No doubt a lot of buyers are eating a lot defects by waiving inspections.

More than a few folks installing solar are using it as an excuse to upgrade their electrical panel so that they can deduct a portion of it using the solar credit.

 

[fbelec]

it's getting harder and harder to do what the home owner wants and keep one panel to curve their confusion. the half breaker is now going away because if you add anything it has to be powered be a arc fault breaker. they don't make them in half size so they take up a full size spot. and with the size of houses and the amount of circuits they have two panels are needed. i serve one home in concord ma that is over 10,000 square feet the house has 4 panels and they are all full next is a 5th panel. if a customer wants a service upgrade we go from 100 amps to 200 amps just because they wanted to. the electric company usually wants to know if there is a current increase and most times no. now with car chargers there will be. so the increase in current means bigger pole transformers or less houses being feed by that transformer.

 

[RustyShackleford]

Ok, I started looking at this yesterday, and it's a setup I've never seen before - not that I've really looked at a lot of houses' electrical systems. The power comes in underground, to a box mounted on the outside of the house, right up against the brick veneer wall. The box contains both the meter and a small breaker panel, which has five 2-pole breakers (100A, two 60A, 40A, and 30A). The wires connected to all these breakers go into the crawlspace - except for the 30A one, which go thru a little box off to the side, and then into the crawlspace. On the far side of the house is a small panel (sub-panel I guess) containing numerous 1-pole 15 and 20A breakers, labeled for things like outlets and lights in various rooms, plus one 2-pole breaker for the clothes dryer.

So my conjecture is that the 100A 2-pole in the big outside box feeds the sub-panel, and the other ones feed the big loads directly.

I imagine that the unit that the 30A breaker feeds thru is one of those things that allows the POCO to turn high-wattage appliances off to handle peak loads. And that it controls the water heater. I don't know how they switch it though, I guess through a high-frequency signal on the power lines ? Oh, and next to the 30A breaker is a label to the effect that there's a 10-15 minute delay after the power is interrupted.

I can't figure out what the two 60A ones and the 40A one feed though. I guess I need to investigate the crawlspace. The minimum ampacity of the HVAC is only 20A (max 25A) so hopefully none of them feed it directly. And there are no other big loads that I can identify. No outbuildings, no EV charger, no well pump, no hot tub.

I'm concerned that the big box is right against masonry (some warned me of that above) but there's no sign of corrosion. A bigger issue is that the cover, which has two parts - the upper goes over the meter and the lower is hinged and goes over the 2-pole breakers - is a mess, it doesn't close up tight at all, and all the latches are broken, including the POCO's seal for the meter. So I'm afraid I'll recommend they have that box replaced, and took a wild guess that it'd be about $500.

Attached are some pix ...

 

[peakbagger]

I think its an easy and good call. That panel is dangerous as its got exposed electrical components. The concern about being up against the brick or concrete was for panels in basements. I think your price is quite low. When an old panel is replaced, it needs to be brought up to code. I dont see a main breaker which I think is required (at least in my area). It could be lot of labor and labor is not cheap. There may be a requirement for AFCI (arch Fault) and GFCI (ground fault) breakers (not cheap). I do not see a separate neutral and ground bar. Many new 240 volt circuits like dryers and ranges need a 4 wire circuit (2 hots, a neutral and separate ground). I am unsure if existing circuits have to be upgraded. My guess is the subpanel needs upgrading as most 120 volt circuits now need to be AFCI and GFCI.

BTW its a mix of aluminum and copper wiring, make sure all the connections are rated for aluminum (many appear to be) and all the aluminum connections need to be coated with non oxidizing paste and torqued and re torqued

 

[Rusty18]

Like he said, from the main panel on any 240v is now 4 wire. Old instal is still legal (around here) with 3 wire and a remote ground but if you have to change anything out you have to bring it up to current code requirements, which is split neutral and ground from the main panel on hence the 4 wire. Wire is not cheap.
Also like peak said there’s a difference between inside panels installed on a block wall and outside panels mounted on a block wall, it likely has offsets stamped in the to get it 1/8” off the block and is sealed up better.
I definitely think it would be worth the hour or two service call to get an inspector/electrician out there to look that over and get an estimate. $500 won’t even buy the new hardware if (when) that has to be replaced. And when they figure out their seal has been broken they will likely get out the fine tooth comb.
Not a deal breaker (I’ve done err seen worse ) but an estimate for replacement could be used to help price negotiation.

 

[RustyShackleford]

They've already moved into the house.

I understand about 4-wire for the 240vac circuits, but don't understand why it's an issue that there aren't separate ground and neutral bars there in the main panel; aren't ground and neutral always bonded in the main panel anyhow ? Now of course it is an issue if there aren't separate ground and neutral in that subpanel (where all the 120v circuits are). And if there's not 4-wire (separate ground and neutral) going from the main panel to the subpanel, then clearly that's the case; I need to check for that, but if there is, why isn't it ok that the neutral and ground don't both go to that same bar in the main ?

Also, are you saying that any 240vac circuit now needs to have 4-wire, even if the attached appliance has no neutral ?

I don't believe replacing that panel would trigger all the upgrades mentioned, here. I asked my AHJ, if I replace MY main panel, do I have to install AFCIs and he said no.

 

[peakbagger]

My non electrician understanding. There is supposed to be only one point in the entire house where the neutral ties to the ground and that is the main panel. The main panel will have a separate ground bar and neutral bar. In the main panel only there usually is a screw that can screw through the neutral bar that ties to the panel case, that is called bonding the neutral to the ground. In any subpanels the neutral bar is not bonded.. That means there needs to be four wires from the subpanel to the main panel. This is where it gets a bit weird if the sub panel is in a seperatestructure. If the subpanel is on separate structure, the recommendation is to drive a secondary ground rod at the subpanel and tie it to the ground going back to the main panel. The weird part is the ground wire should not be run through the main building, rather it should be routed around the building and then tying into either the main panel ground or the primary ground. The reason for keeping things separate is to keep any power flowing through the ground system of the house.

As mentioned, older appliances and other 240 Volt equipment on occasion needed some 120 v so they just hooked from one hot to ground and that puts some current into the ground bus. There are exceptions to the need for four wire circuits on 240 circuits and I do not know where the line is drawn. My is set up for 3 wire 240 volt EV charger no need for a 4 conductor plug.

 

[RustyShackleford]

There is supposed to be only one point in the entire house where the neutral ties to the ground and that is the main panel. The main panel will have a separate ground bar and neutral bar.

It seems to me that since you know the ground and neutral bar will be tied together, why separate bars ? I know in my own house, wired by a professional electrician, and inspected, in 1988, there is only one ground/neutral bar (actually one on each side of the columns of breaker, tied together) and the neutrals and grounds are connected to them indiscriminately.

As mentioned, older appliances and other 240 Volt equipment on occasion needed some 120 v so they just hooked from one hot to ground and that puts some current into the ground bus. There are exceptions to the need for four wire circuits on 240 circuits and I do not know where the line is drawn. My is set up for 3 wire 240 volt EV charger no need for a 4 conductor plug.

Yes, many appliances have a neutral and many don't. My confusion is that I understood some of the above posters to say that ALL 240v circuits are now required to have a neutral (in addition to the ground).

 

[fbelec]

from what i see the 100 amp should be tied into the bottom of the meter and that is your main breaker. the rest should be feed through the back feed 100. the two 60 amp might be separate sub panels or one might be the air conditioning. nothing has to be changed to a arc fault or gfi breaker. even if you change the box it will still be hooked up the same way. the only one that knows why main panels neutral and ground are bonded together is incase you lose a neutral it can run on the ground. any other panel is considered a sub panel and neutral and grounds are isolated. if one of those 60 amp breakers are a sub panel then the wire that feeds the sub panel will need to be 4 wire one being a ground. if the other 60 amp breaker is a out building the if upgraded the sub panel in the out building will need a ground rod. anything that is there now is grandfathered in and nothing needs to be changed. the only 240 volt appliance that need a 4 wire is a sub panel and new stove circuits and new dryer circuit. the other thing i see that is wrong is the piping from underground or elsewhere up against masonry should not be pvc pipe but steel

 

[EbS-P]

The AC compressor is probably on the load control device. It looks much older than what Duke installs now. Hence the 15 min time out not wanting to turn the compressor on and off and on. Quickly. Just a guess one 60 amp may be resistive heating strips for the AUX / emergency heat. Are there natural gas or propane appliances?