I had an electrician run a 220v line for a hot water heater.
My main panel was full and he brought a sub panel, wire, and other needed parts.
The electrician discovered a small padlock on the meter box. It wasn’t the standard seal that could easily be removed. I had no idea the power company had done that.
He couldn’t kill the power & safely wire the sub panel onto the main bus in the panel.
He went back to the store and bought a 60Amp breaker for the old panel. Removed a old breaker and installed the 60Amp breaker. Connected the sub panel to that breaker.
The “borrowed” circuit went into the sub panel.
He told me the 60Amp breaker could be replaced with 100Amp if I add more circuits to the sub panel.
I got worried when the electrician had to switch his plans. I even offered to purchase small bolt cutters to remove the padlock on the meter box. I know that would have ticked off the utility. But killing the power makes the job so much safer.
Thankful he came up with plan B. Cold showers are miserable this time of the year . I needed hot water.
Btw, I “think” the electrician changed his plan because the power couldn’t be shut off.
It seemed like it because we had just discussed the meter box padlock. He left immediately to buy the 60Amp breaker. He had already bought everything else.
He may have intended on wiring it this way. Working on it hot was just an annoyance. I didn’t ask.
It’s not really “working on it hot”. Turn off the breaker before disconnecting the wires hooked to it and that is dead. The breaker connects to the bus, but as long as it is off, you’re not disconnecting anything under load. Plenty, maybe most, breakers are installed in this way.
The only dangerous part is feeding the line from the sub-panel into the hot main box. US ground wires are bare copper, and you have to keep control of the suckers. I had one spring out of my hand and short across the two hot bus bars, and it kept shorting until it burned in two!
Stupid question, maybe but… why can you not just turn off the main breaker to the house at the top of the panel (or did it not have one? Mine has one; my old house from 1963 had one)
I assume once the main breaker is off the whole panel is dead, no different than working on an outlet with the breaker off to that outlet. (But not being an electrician, I was not about to test this theory)
As for the configuration - if you were putting in a subpanel in, say, the garage instead of beside the main panel, I assume that too is how you would do it. High-amp breaker in the main panel, feeding the sub panel. As mentioned - as long as the wire can handle the current, and as long as the main breaker for the whole house can handle the full load.
I recently put a 40 amp circuit to feed a stove plug (NEMA 14-50) in my garage for charging the car. Then a few months later, I changed it to 50A and had to replace the 8AWG wire with 6AWG (copper) to accommodate the higher current. One thing I learned, 40A or 50A is peak. If you are going to run continuous (let’s pretend, to charge a car for several hours) then the current should only be 80% of the rated amperage. Plus - I scheduled my car to charge at 1AM, and make a point of not running the dishwasher, clothes dryer, and oven at the same time so I can be confident that I will not pop the 100A feed main breaker. I did not want to pay for expanded electrical service.
I appreciate your answers. I’m not familiar with wiring main panels and sub panels. Except for turning a breaker on/off. This experience has taught me something.
I was a electronics service tech (TV & stereo) before returning to college and switching to computers. Completely different training and skills compared to electricians.
No kidding. I was trained as an electrician and worked in that capacity for years. I couldn’t guess at how many times someone asked me if I could fix their TV. My answer was usually “I can fix it so that nobody can fix it.”
Your electrician did it correctly but you need to check the following:
Electrical panels come with the neutral bar tied to the ground bar with a solid copper or aluminum link. They are effectively bonded together.
NFPA 70 code requires that this link be removed if the panel is a sub panel. This separates the neutrals and the grounds at that sub panel.
If you bond them anywhere other than the main service, the neutral return current now has multiple paths including your ground conductors.
So check that.
One other note, you stated that you could later replace the 60A breaker with a 100A device. You can do this ONLY if the conductors between the breaker and the sub panel are rated for 100A or more.
ONLY if the new panel is fed with wire capable of the entire rating of the main breaker feeding it and if there is a set of lugs at the main breaker to connect the wires to. Quick answer - I’ve never seen such a critter. What you describe is not normal and there’s probably no legal or safe way to do it.
Almost. The wires coming in from the meter and connecting to the top lugs are before the main breaker, so they are still live. But they are pretty easy to avoid, and everything else in the box is dead.
Not if it’s supposed to be a subpanel. That would be a second main panel, and so should be fed directly from the meter, not from an existing main panel. I don’t think that would meet code at all.
The way your electrician did it is, as beowulff said, the proper way to do a subpanel.
Probably because he couldn’t get a 100A breakers on the day they were doing it. They aren’t commonly stocked in stores; 60A is usually the largest size on hand. It’s what is commonly used for subpanels. Plus the wire he was going to may have only been enough for 60A.
That’s correct. The store only had 60amp in stock.
I was told 100amp are quite expensive and harder to find.
I probably won’t add any more circuits. But, it wouldn’t be hard to upgrade the wire, if needed. The sub panel is less than 12 inches from the main panel.