We have a DC electrical service with, one bad leg. Looking to replace the conductors. My question is, as I have limited experiance with DC, what type of PPE would be required to cut, and reconnect this service live?

Or is that just a dumb question?

I am sorry I can not answer your question surly someone here can, but I did want to say that it is not a dumb question.

Pat yourself on the back for asking questions about safety. I only had to deal with a DC service once and the unknown made me very nervous.

Bob

I design a lot of DC power plants. What voltage and power levels are you talking about?

100A -150A 240VDC Thanks!!!

Why do you have to do this live? Is this so important an installation that you will risk getting blinded, burnt, killed?
One thing I know about DC is that it has no neutral point, so that means you would be cutting it at full amperage.
Would it be possible to attach a temporary bypass around the damaged section you wish to cut out?
~Peter

Should not a lot different than an AC circuit of similar ratings.

Can you deenergize the source to work on it? Obviously, a DC voltmeter/indicator would be used to check for dead.

It's a customer owned U/G service lateral prior to the disco, the utility won't drop the area, of course, or re-pull it. We are trying to get them to cut, and re-connect. But, "P" stands for premidona, in PG&E, (Our POCO, actually SF County Hetch Hechy, but they maintain it.)so they may cut, and not re-connect. (Or vise versa.)Leaving our customer without an elevator.
----------------------------------
I can kill it at Zero Amps, by killing the disco, as it already is, but the voltage in a Christy box, leaning in a hole is what I worry about. Reaching in an live 240/480VAC street box, doesn't bother me. I know the risk, and the protection level for it. With DC, I have always worked dead, and locked out.

[This message has been edited by e57 (edited 09-11-2004).]

I agree, this is not a dumb question.

If the situation can not be made safe then it may be a job you don't want.

I know that is easier to say than do.

From someone who was burnt in an arc blast, I will say, living without scars and going home healthy is whats important.

We work a lot of hot situations in hospitals, but if the situation is to precarious, a "SHUTDOWN" will be scheduled for late night, early morning, holiday, etc... regardless of inconvenience or expense.

I'm sorry I don't have any real info on your original question.

Roger

Hey Bjarney, Thanks!

00 gloves are rated for 500VAC/750VDC

OK, I have to ask. What is the application for this DC service? And DC services in general.

Peter

From a PPE point of view, there is no difference from a standard 240/120 AC system. There is still the same amount of arc flash and potential difference.

Peter, alot of downtown SF, CA, and a lot of other older cities were wired DC and AC during the Westinghouse / Edison debacle AC vs. DC. And for some motor applications in industrial areas DC was prefered, a lot of them still exist and operate here. Although you can not get a new DC service, you can maintain an existing one.

Most of which require very little maintance, as they have survived this long. About 100 years! Although so far I have relaced several conductors, and a few contacts for motors. This is the only live work I have come across needing to be done. And, it looks like we'll get PG&E to cut it.

My only real question really was glove ratings. As I went to Salsbeury's site sever times and couldn't find DC ratings at all, Until Bjarney found them.

And, it looks like I'm due for some gloves anyway... Think I should get some 0 rated gloves, you know, for around the house.