No problem with voltage on the neutral bar, but you need to be acutely aware of the conductors coming into the box from the meter. The main breaker shuts off the rest of the box, but the conductors coming to the main breaker from outside are extremely dangerous, as much for current capability as for voltage.

Besides the risk of touching those conductors and getting shocked, if a tool gets between those and the box frame you will have molten metal spraying all over the place.

Normally there isn't an issue. However, if you happen to have a neighbor with a bad neutral connection to the transformer in any of several places, there can be significant current on various grounds in the panel. These include the ground rod and water pipe connections. To err on the side of caution you should use an AMP clamp to see if current is present on the neutral after turning off the main.

This situation, while rare, happens often enough you should be aware of it and check for it if you are for any reason removing the grounding electrode conductors or water pipe bonding wires (the BIG ground wires attached to the buss). Lacking test equipment, at least use pliers with insulated handles to remove the big wires if you do.

While much rarer, this situation can occur on grounds from water heaters, heating equipment, and hot tubs/spas.

Turning the power off at the meter doesn't matter for this issue as the grounds and neutral are tied together.

Just treat ALL wiring as if it is hot till you know otherwise.

billhart and unclebill, thanks for your replies.

I understand that the 2 hots under the lugs of the main breaker are live and dangerous and to be treated with care.
I will carefully tape over the area where the main breaker lugs are.

My concern is if the main breaker is off and I remove all the neutrals and grounds for the branch circuits, leaving only the neutral (grounded conductor) and the EGC which is connected to the cold water pipe close by, can the neutral bar still have current on it? I was thinking of unclebill's statement about a ground fault from a neighbors house on the same transformer. I live in a large city, in a row home and there are 13 homes that I know of on this transformer.

Any thoughts on this?

Thanks in advance!

"Can the neutral bar still have current?" It certainly shouldn't, but that doesn't mean it won't. Test everything twice (make it thrice), and take nothing for granted.

I guess I was a little hasty in my original answer. I agree with lonesparky that it shouldn't but there are situations where it could be hot when you open the connection.

Having 10 amps or so flow through your neutral and ground from a neighbor could happen whether or not there was much voltage behind it. Maybe yours is in a more direct path and some of the neighbors current comes through your connections. You might open it and find a volt or two.

Or if yours is the only good connection (very unlikely) in the neighborhood served by one transformer, then opening it could leave you with any part of 240 volts on the opened line and cause lamps and appliances to burn out in the neighbors houses. This is only true if they ALL have bad connections.

Sort of reminds me of the time I was on a guy's farm and he told me they had once turned off the big switch outside and some appliances burned out in the house. I couldn't make any sense out of that--you should always be able to shut off a switch. Then I figured the "electrician" who had installed the 3-phase high-leg wiring for feed augers had just added another switch on the high leg (only) instead of using the code-required 3-pole switch. Thus if you left the high leg on and turned off the other two legs, 200 volts from the high leg would go through the motor loads and show up on the 120 volt receptacles, including in the house. Just because it should be safe doesn't mean it is and like the other guys said you need to check not assume.

Thanks for the info. Will check thrice with clamp-on amp menter and proceed from there!

My first thought is that you have to ask the question you need somebody there with the appropriate knowledge and tools to accomplish this.

Next question, does the main breaker actually shut everything off? Mine doesn't.

Ground currents can be measured with a clamp on amp meter. I measured about 15A on my cold water pipe and about 10 on the gas line. The meter was lying on the ground during these measurements. Yep one of my neighbors has a bad ground.

I would recommend that you get some help, you can get into a big mess if something does not go as expected.