Circuit Breakers or Fuse panel?

[circlew]

400 Amp Service

The house I'm renovating is getting a 400A service due to the electric heat (backup resistance heat for the heat pump). The meter base and underground wiring are in, and I'm waiting for the main distribution panel to be installed after some other work is finished in the basement. The meter base is self contained, and is called class 320, as it is continuous rated at 320A. I would have had to have a CT (current transformer) cabinet and separate meter base installed to get a full 400A rating.

400A services are common in larger new homes in this area, especially if they do not have gas service. I have been in very large homes (mansions, over 8000 sq. ft.) that have 800A service. These houses have multiple air conditioning units, and one had a large in-ground swimming pool.

The utility co. here doesn't charge extra, but I had to buy the meter base, conduit and wire going from the pole to house. Higher rated equipment is naturally going to be more costly.

When I went to Homearama last month, one house had a receptacle for charging an electric vehicle. I didn't see the electric panelboard, but imagine it was 400A anyway due to the size of the house being approx. 6500 sq. ft.

I'm not planning to install any provisions for electric car charging at my home, due to that type of vehicle not being very practical where I live. Such cars make more sense in an urban area.

 

[sudsmaster]

"Cheater plug"

Older knob and tube wiring doesn't usually have a ground wire. The junction box likely would NOT be grounded, so a "cheater plug" would be worthless for such an outlet. The only way to get a grounded outlet is to attach the ground socket to a good ground.

Nowadays I've noticed that non-grounded outlets are generally not carried by the home improvement stores. Because this '41 house had a number of non-grounded outlets that were worn out to the point that plugs wouldn't stay in, I changed them over to new grounded outlets. Since I'm the only person here, I know which outlets have real grounds and which don't. Eventually I'll have the knob and tube replaced with modern wiring. Half the house (kitchen, family room, laundry closet, enclosed patio) has excellent wiring... either rigid conduit that acts as ground or metal armored cable, armor as ground). The rest, I could, as an interim solution I suppose, run ground wires from the various outlets, under the house, to the rigid grounded conduit for the other wiring. It's not the optimal solution (I understand that all ground wires should be routed back to the ground bar in the breaker panel).

When I get a round toit...

 

[mattl]

The center screw of the 2 prong outlets I've see are bonded to the neutral side of the plug giving it the same potential as a ground connection. this does not require a grounded junction box or wiring. The third prong is to ground the case of metal equipment preventing a shock. This was not totally successful hence the GFI was introduced.

As I mentioned problems arise if the plug is wired with the leads reversed. If that is the case the center screw is connected to 120v. What ever you plug in will still work, but be very dangerous. Old tvs often had hot chassis due to this and the fact that most plugs in the old days were not polarized. Same with lamps and just about anything plugged in.

Wiring today is light years ahead of what it used to be. Polarized plugs, GFIs, arc fault breakers and improved standards have made our homes much safer. That being the case a little diligence is still required. I'm in the process of doing something most won't do or feel comfortabe doing, I'm going room by room and pulling out each outlet and switch to check for loose or broken wiring, and replacing any outlet that feels sloppy when you plug something in. My house was built in '65, under wired or close to it for the times. I've pretty much rewired it adding a great many circuits, but the plugs have been mostly untouched. I have found a few issues and glad I did. I still need to break up one kitchen circuit, and go through a few rooms, but I feel much better knowing the wiring is solid.

 

[MaytagA710]

Hey Rex!

We use fuses in conjunction with our breakers too. All of our VSD/VFDs are breaker controlled, but have a fuse right after the modulating component and before the filtering device. 

 

I dont think you will be able to find unpolarized or ungrounded plugs anymore Rich. They are no longer up to code in Canada, I am not sure what they are in the US. But Canadas electrical code banned them in the early to mid eighties. 

 

[lordkenmore]

Ungrounded outlets

"non-grounded outlets are generally not carried by the home improvement stores."

"I dont think you will be able to find unpolarized or ungrounded plugs anymore Rich. They are no longer up to code in Canada, I am not sure what they are in the US."

I don't know electric code, but I can say with certainty that all electric systems I've seen made in recent decades have had nothing but grounded outlets.

But the older style outlets might still be around as a specialty item for repairing older systems. Problem is: you don't see specialty items at Home Depot. All they want to carry, or so it seems to me based on my nearest Home Depot, is that which you see in modern development houses.

If nothing else, there are probably small hardware stores with a pile of unsold old style outlets....

The real fun with repairs come to systems that have really obscure standard components. One of my grandmothers had some outlets in her house that were longer obtainable--at least locally. (Again, it might have been available as a specialty item.) Nothing new could be fitted (physically, let alone dealing with modern niceties like a true ground). So when an outlet wore out, the only choice was swap it with another outlet. I suspect whoever had that house next probably ended up having to do a total rewire.

 

[lordkenmore]

Circuit breakers are better than fuses

was a comment above. This is not something I'm qualified to debate, so I won't. But I will make one comment: one important issue is that the breaker must be a good design. There are, unfortunately, plenty of bad circuit breakers out there. While one hopes the currently available brands are safe, there are still plenty of unsafe panels out there. If faced with a choice between living someplace with an unsafe panel, or a fuse box, I'd go with the fuse box. Fuses have dangers, and hassle, but unlike some brands of circuit breakers (thankfully gone), they do stop an overloaded circuit.

Of course, a panel can be replaced, but that's not cheap. For a renter like me, you're stuck with what you have, until and unless the landlord decides to make changes.

Speaking of replacements, this may be garbled, or something that only applies to limited circumstances (say the state one is in). But someone at Ace warned me about bad service panels. Part of his warning was that he knew of cases when someone made a relatively minor change to the electrical system, but a change that was big enough to require an inspection. Upon inspection, the person failed, and was forced to replace the service panel because it was a "defective design" and no longer meets code.

Link to web page "Is My Electrical Panel Safe"

http://ismypanelsafe.com/

 

[tolivac]

Some of the very large homes I had heard about were wired with 3 ph 208V-120V service-the HVAC equipment the major load there.
Some very old breaker panels can have defective breakers-age effects the trip sets for the breakers-esp if they are thermal type breakers.
Just yesterday at the transmitter plant brought up an older Tx and BANG!!!!from the transformer vault-2 "grasshopper" capacitor fuses blew-and it tripped the 4160V breaker-no harm done-except the fuses-the Tx is OK.The fuses are old or homemade the solder joints on the fuse wire can let go.When the fuse blows-the cap is grounded for safety.Therefore--the BANG!
I have heard of fuses for VFD's either for the primary input side of the invertor or its sec output side.Again for protection from short circuits-like a wiring fault or a shorted motor.The VFD can be MORE expensive than the motor-so they are usually well protected.
the best breakers use a magnetic trip design.Its more resistent to aging-and the tripping current is more constant.
and breakers for residentual use or industrial uses have "curves" the trip currents and how much of an overload and the time-before the breaker trips.same sort of thing for fuses.

 

[sudsmaster]

OK, so here's my plan for grounding the knob and tube outlets:

Run a ground wire from each outlet to a main wire that in turn is bonded to the 1-1/2" rigid conduit that runs under the house and functions as an effective ground for the newer outlets.

I was thinking of using standard green 12 gauge solid core copper wire. Is that enough, or do I need to run it through conduit, or do I need to buy some Romex and use only the ground wire in the Romex?

This would be an interim solution, mainly to provide grounding for electric equipment (like the TV and stereo in the living room) that would benefit from it. The long term solution would be to replace all the knob and tube with Romex, armored cable, or rigid conduit, or some combination thereof. The knob and tube runs through the attic; the grounding system I'm thinking of installing would run through the crawl space (where access to the rigid grounding conduit would be easy).

The rigid conduit dives down under the house for a 100 foot run to a separate workshop building. Between that and the service ground I think it provides a pretty reliable grounding system. I could add a copper plated steel grounding rod at the service panel/meter if necessary (been thinking of doing that for a while now).

 

[cadman]

Just a few thoughts- I have never seen an ungrounded receptacle that has its strap tied to the neutral conductor screws. Are you sure about this Matt?

Non grounded recepts ARE still available at the box stores. Maybe some locations don't carry them but I know they're available around here. Helps prevent people from putting in a grounded one in a non-grounded installation in an older home and not having the third prong connected to anything. To check for availability at your local HD, keyword search Leviton+Receptacle.

I actually used nos bakelite non-grounded recepts in my new construction (not everywhere of course) but where appropriate, rather than current production. Both are available out there.

 

[cadman]

Be careful if you decide to run separate grounds to the recepts! Electrically, neutral is ground, ground is neutral.

When you pick up a separate ground source, there's no guarantee it'll be at the same potential as your current neutral. If there is an imbalance, you stand to actually make things MORE unsafe and risk damaging electronics at the same time.

Wire length, connection integrity, system loading, ground rod number and placement, soil moisture, etc. all can affect this. If you do run a ground wire to all your recepts, make sure you bond it well to the neutral conductor in your main panel. Verify that the system ground source (the original to the house) is in good condition and grounded well outside. 12ga is fine. Heavy loads can put a toll on that neutral/ground source at the original panel, and you certainly don't want that failing, or you'll find a lot of your 110v appliances now have 220v across them!

 

[mattl]

You NEVER want multiple grounds! All grounds must be bonded together with at least a #10 copper wire or it's equivalent. If you don't you will have different potential at various points in your system that can cause equipment or you to balance out the difference.

 

[volvoguy87]

On vintage electrical systems.

I am refurbishing a huge house built in the early 1880s. The 1st electric system is mostly intact and still in use. It was installed prior to WWI (we think) and is all knob and tube. I have absolutely no plans to get rid of it either. The fuse box was replaced with breaker boxes (100 amps each) as part of a wiring project in the 1990s or 2000s.

Old wiring, if its in good condition, should perform in accordance with the specifications of the original design. Bearing that in mind, you just cannot overload it and expect to keep on running. If you've got fuses, ALWAYS keep a spare or 3 of every type of fuse. When I add circuits, I add new ones (I don't tap old circuits) on new breakers of appropriate amperage for my application. I also prioritize new circuits for the highst-demand applications first to reduce the load on the existing circuits.

As long as you keep the load within the original design specs, your old wiring can continue to serve you safely and well.

Dave

 

[lordkenmore]

"As long as you keep the load within the original design specs, your old wiring can continue to serve you safely and well."

I personally would not mind living with an old system, as long as it is still in safe condition, and has enough capacity for my needs. Frankly, my needs are modest. My grandparent's house (mentioned above with the obscure outlet story) was probably woefully under wired by most modern standards. But I don't recall them having problems, apart from replacing obsolete outlets. I could easily live with what they had. Then, again, I don't have hundreds of electric gadgets constantly running, either.

Ironically, in time, old wiring systems that seem hopelessly limited may actually be acceptable for normal people, now that we are in a more energy conscious era. One obvious example: power requirements for computers has gone down for many people, as they shift from large desktop machines to laptops. I think I have even seem laptop power supplies that don't even require a ground connection.

 

[lordkenmore]

I don't tap old circuits

Tapping into existing circuits seems to be a real problem. A house on my property apparently saw a lot of that. Anytime the people who built it had some new need or interest come up, they got creative. The house has been partly updated/redone since that era, and I was told it was quite an adventure dealing with fixing the wiring so it was actually safe and within code.

 

[MaytagA710]

Cory! You cannot and should not ever connect neutral and ground together. Ever. Neutral and ground are two totally different things. Should never mix. It doesn't tie in back at the panel in your house at all. Neutral goes back out to the pole which then goes to the nearest substation, back to the electrical vault etc... Ground goes right to one thing, and one thing only, to the earth. In homes they are mostly tied to the water main pipes, or there is a huge ground steak in the basement some where. Ground wires should always be larger then the rest of the normal sized gauging for the house, in case of multiple ground faults. 

 

If you have multiple ground sources from various things such as switch gear, motors, etc... thats fine, but at the end of the line, they have to tie in to one point and, by using a grounding bus bar. This bus bar will then be tied into the earth. 

 

Neutral is designed to carry and balance a load which is not complete or using all the voltage allotted. The purpose of the ground is only to allow the safest way possible to the ground in the event of a ground fault or other electrical faults. Its a form of protection from all kinds of electrical faults. 

 

Connecting Neutral to Ground in your house will only allow your house to catch fire significantly faster than normal. 

 

[wayupnorth]

Old wiring

The first apartment I rented when being on my own in the early 70's was owned by a very nice old lady. She lived in one unit and the other 7 units paid for itself and gave her a little something (rent was cheap). But that whole apartment had 7 ungrounded outlets on one 20 amp fuse, so cube taps and extension cords were a necessity. When the refrigerator started, the TV picture would close up, so you get the picture. After moving out and buying my first place (fortunately rewired fine) a good friend bought that apartment house after she passed away and it was almost 25 grand to redo all the complete electric service and eliminate all the miles of knob and tube wiring in that place. He did raise the rents considerably and his electrician could not understand why there had not been a fire.

 

[blackstone]

A Few Comments….

I live in an older house (pre-1900, I think); most likely predated electricity, since there are gas fixtures remaining, which had been used for lighting. Obviously, these gas lines are not still connected, but they do make interesting decorations where they remain. A number of gas pipes are still inside the walls.

i still have fuses. The single biggest thing that has greatly reduced the number of blown fuses is more efficient air conditioners. Those old ACs, while they would last forever, with their sealed all-copper lines, blowing really cold air, used just too many amps. I have 3 air conditioners, on 3 different circuits, and can run them all day long (out of necessity). With the old ACs, I could have actually felt warmth in the wall outlet. Now, the only concern is to shut off the AC when I have to use the microwave or the Keurig.

One other point. When rewiring, I always use metal-clad (MC) instead of romex. It's more work, but I feel that it is safer. No chance of accidentally hammering a nail into the wire sometime in the future. No chance of a squirrel chewing through the insulation. The MC now has a ground wire inside, instead of relying on the metal case to be the ground. I even found 4-wire MC at Home Depot, for wiring 2-way switches for hallway lights.

 

[mattl]

MaytagA710, every main panel I've installed or worked on has the neutral and ground bonded together.  The only time it's not is if the panel is used as a sub panel.  Wiring standards do vary by local though.  A quick Google search came up with the link below.

 

 

 

Thanks for reiterating the point I made a few posts back that all ground rods must be bonded together.

http://www.hammerzone.com/archives/elect/panel/sub_panel/01/new.htm

 

[toggleswitch]

"Connecting Neutral to Ground in your house will only allow your house to catch fire significantly faster than normal."

?????

In New York City and Long Island the incoming (service mains) neutral conductor is grounded right in the main circuit breaker panel, and also gets grounded to a copper stake in the earth.

 

[cadman]

Toggles and MattL are correct. The neutral and ground must bond in the main panel to achieve equal potential. The ground rod at the transformer vault sets the center tap of the secondary to ground as the reference. Because only three conductors enter the home, a "ground" must also be established w/respect to the neutral at the main point of distribution. -Cory