DC Plant OPD

[tkb]

We do quite a bit of work for a cable company and we install and maintain some of the DC plants.
We always install an OPD for the battery strings.
One of mucky mucks for the cable company is asking why we need to install an OPD and is looking for a code requirement for this.

Is the OPD on a DC battery string a NEC requirement or some other requirement?
I am trying to find it in the NEC but not having good luck with DC.

 

[qcroanoke]

We do quite a bit of work for a cable company and we install and maintain some of the DC plants.
We always install an OPD for the battery strings.
One of mucky mucks for the cable company is asking why we need to install an OPD and is looking for a code requirement for this.

Is the OPD on a DC battery string a NEC requirement or some other requirement?
I am trying to find it in the NEC but not having good luck with DC.

I asked a question similar to this and this was Don's reply:

Chapters 1 through 4 apply generally and there is nothing that says the rules in Article 240 do not apply to DC circuits.
__________________
Don, Illinois

 

[iwire]

We do quite a bit of work for a cable company and we install and maintain some of the DC plants.

Would one of those places be off Branch Ave Prov? :smile:

I think I saw one of your trucks yesterday. :smile:

I agree with Don above, 240 applies to DC as well as AC, batteries as well as generators etc.

That said the question is does the NEC apply to this part of the utilities equipment?

90.2(B)(4).

It would be good if Dereck jumps in, he deals with this all the time for telephone plants.

 

[tom baker]

Take a look at NEC article 480, storage batteries. A short circuit on a battery load can cause the battery to explode. There are high levels of available short circuit current.

 

[dereckbc]

Well my answer may not apply, but in the 30 years I have been design/building DC battery plants installing any type of OPD is forbidden in the TELCO industry. The recitifers have breakers, and the distribution has fuses, but the batteries are solidly bonded to the charge buss.

Since this is a CATV utility they can pretty much do what they want anyway IMHO as NEC does not apply to them.