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#41895 - 09/10/04 02:27 PM Repairing DC electrical service  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
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?


Mark Heller
"Well - I oughta....." -Jackie Gleason

Work Gear for Electricians and the Trades

#41896 - 09/10/04 02:37 PM Re: Repairing DC electrical service  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
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. [Linked Image] I only had to deal with a DC service once and the unknown made me very nervous. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#41897 - 09/10/04 05:12 PM Re: Repairing DC electrical service  
dereckbc  Offline
Member
Joined: Oct 2003
Posts: 156
Tulsa, OK
I design a lot of DC power plants. What voltage and power levels are you talking about?


#41898 - 09/10/04 05:58 PM Re: Repairing DC electrical service  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
100A -150A 240VDC Thanks!!!


Mark Heller
"Well - I oughta....." -Jackie Gleason

#41899 - 09/11/04 12:32 AM Re: Repairing DC electrical service  
Peter  Offline
Member
Joined: Jun 2004
Posts: 92
San Diego
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


#41900 - 09/11/04 01:21 AM Re: Repairing DC electrical service  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
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.


#41901 - 09/11/04 02:34 AM Re: Repairing DC electrical service  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
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).]


Mark Heller
"Well - I oughta....." -Jackie Gleason

#41902 - 09/11/04 08:13 AM Re: Repairing DC electrical service  
Roger  Offline
Member
Joined: May 2002
Posts: 1,716
N.C.
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


#41903 - 09/12/04 08:44 PM Re: Repairing DC electrical service  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Hey Bjarney, Thanks!

00 gloves are rated for 500VAC/750VDC


Mark Heller
"Well - I oughta....." -Jackie Gleason

#41904 - 09/12/04 08:53 PM Re: Repairing DC electrical service  
CTwireman  Offline
Member
Joined: Feb 2002
Posts: 840
Connecticut, USA
OK, I have to ask. What is the application for this DC service? And DC services in general.

Peter


Peter

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