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250/250/200? #120486 04/13/05 05:06 AM
Joined: Dec 2000
Posts: 4,286
electure Offline OP
Member
Quote
PM asked if I could take a look at a service, where she has a bid for a TI that spec’ed a 400A service.

This is part of my note back….. (She often cuts and pastes my note back to customers, that’s why its too detailed.)

The service for (That joint) in question is described as follows:

MOCP 250/250/200A (via adjustable trip setting breaker) 240V Ä 4W (Delta High Leg) w/ reduced Neutral, and High Leg Conductors (2/0 Cu TW) rated for 145A and further de-rated at 80% to 116A per 1999 NEC 310.15 (B) (2) (a), not including ambient temperature correction. Phase A, and C conductors are 350MCM Cu, with TW type insulation, rated for 260A, and further de-rated at 80% to 156A per 1999 NEC 310.15 (B) (2) (a) to 208A.

All service conductors are part of an assembly comprising 6 service disconnects tapped from a single tap section fed by parallel conductors comprised of 2 sets of service laterals of 350MCM Cu TW (700MCM) for phases A, and C, with reduced Phase B, and neutrals of 2/0 Cu TW (4/0), rated for 385A,and 195A respectively, and further de-rated at 80% per 1999 NEC 310.15 (B) (2) (a), to 308A,and 156A respectively, not including ambient temperature correction

e57


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Re: 250/250/200? #120487 04/13/05 06:32 AM
Joined: Dec 2004
Posts: 329
I
IanR Offline
Member
Whats the deal with the last pic? Is it an abviously unbalanced 3 phase service or does it supply 3 different sevices?

Re: 250/250/200? #120488 04/13/05 06:33 AM
Joined: Dec 2004
Posts: 329
I
IanR Offline
Member
Never mind, I see. Guess I should read in a little more detail 'fore askin stupid questions.

Re: 250/250/200? #120489 04/14/05 08:17 PM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
You can't tell by the pic's, (I cropped the last pic' too close, but B and C are rotated) the trip settings were never adjusted, making phase C, or B (Depending where you are in the service) MCOP 250A, on a service lat. that covers 2 other parts of 6 services on wire rated for only 156A.

The "on-paper-engineering" that accompanied the bid for this job spec'ed existing service equipment at 400A, (which is what the panel section that it is in is rated for, not the breaker or wire feeding it, or in total capacity of the service wire.) the space it will serve will use every bit of it.

We lost the bid by $20k, not including the service. We think because they either wanted to get an "in" with our client, or forgot $20k worth of lighting. Either way, they low-balled a nightmare, good luck to them, as the service will also be hell to re-do, impossible to make real money from. The client will hold them to the details, and walk them right to the cleaners.


Mark Heller
"Well - I oughta....." -Jackie Gleason
Re: 250/250/200? #120490 04/18/05 07:32 AM
Joined: Jun 2001
Posts: 642
N
nesparky Offline
Member
May the lowballer get cleaned out and get everything they deserve.
A job like that should be bid with a lot carefully thought out exclusions for the problems that show up after the walls are opened up.


ed

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