3 phase meter CT w/disco- Mass Guys,nstar

This is a question for the Massachusetts guys and NSTAR requirements.

We are bidding a job with these requirements and first off I want to be sure I am putting the correct pieces together for my supplier quotes.

400 Amp 3 phase 4 wire 120/208v service

there is a 400amp MDC panel with a 400amp main breaker in it - but before you get to that coming in from the underground they are calling for a CT cabinet/Main disconnect approved by NSTAR.

I want to use Siemens brand. I've been looking at the new nstar blue book and I've never done a set up like this before so I want to be sure I am setting this up correctly.
I believe nstar is calling for "cold sequencing" or a disconnect on the line side of the CT cabinet - is this correct and does it have to be a fused disconnect?
do they make a ct cabinet /disco combo built in together?

So I am thinking it would go like this - underground conduit into building to a fused 400amp disco then to a CT cabinet with the meter box tapped off the ct cabinet - out of the ct cabinet to the MDP 400 amp 3 phase breaker.

Does this sound correct to guys having done something like this before? anyone have a model # for the ct cabinet or meter? or am I way off here?
thanks for any help.

CT, I'm not from there, but I would think you should already have a field engineer from the POCO assigned to you, and who can answer these questions.

If you haven't contacted them yet, I suggest you do so. Other's in this forum can answer more than I.

CopperTone,

I have designed 3-phase services in the Nstar area, They usually want cold sequence where they want a non-fused disconnect before meter/CT cabinet. If you are comming from utiltiy riser pole underground, hit the service rated disconnect, meter, then into the panel with the MCB. You should be OK, make sure your 400 amp ratings are the same on your equipment, you may also check with there Engineering. Every area inside there loop can change depending on who you speak with.

JWC

JWCELECTRIC said:

CopperTone,

I have designed 3-phase services in the Nstar area, They usually want cold sequence where they want a non-fused disconnect before meter/CT cabinet. If you are comming from utiltiy riser pole underground, hit the service rated disconnect, meter, then into the panel with the MCB. You should be OK, make sure your 400 amp ratings are the same on your equipment, you may also check with there Engineering. Every area inside there loop can change depending on who you speak with.

JWC

Click to expand...

thanks for the reply - I spoke with a couple of people from nstar today and they do require the cold sequencing and they specify a particular CT cabinet and meter socket - they just couldn't tell me which one without a work order - (well it depends on certain things, etc, blah blah). Since we are just bidding at this point - they were useless.
I called the engineering co that designed the system on the prints and told them to get me the information - spec a cabinet , meter and dicso - even if it is wrong - for bidding purposes. I didn't want to put too much into this at the bidding stage. I just hadn't run into this before.

In your bid cover your cost for a meter socket with a bypass, then when you get the bid call NStar to see if they will accept the ct cabinet instead to save $. Also check the 2009 Blue book they may only want cold sequenceing on 480V 3-Phase, Then you may also eliminate the disconnect switch.