Fused disconnect vs Circiut breaker

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mjc

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Hi, an Arch/Engineering Firm has drawn a riser diagram with a Transformer feeding an 800amp CT Cabinet. Then dispersing 200amps to each of 4 separately metered tenants. According to the 02 NEC 230.40 Ex 1 this is ok.
Then they go on to include installation of 200amp FUSED DISCONNECTs between the meters and a 42 ckt Panels. My design intent (in order to save the cost of the disco,fuses,pipe,wire,and labor ect.) would be to eliminate the fused disconnect and purchase 42 ckt. panels with 200amp MAIN BREAKERs for each location. According to the 02 NEC 230.90(A)ex.2 this is code compliant or am I reading more into it than I think?
Thanks, thought I'd check with the Pro's before inserting foot in mouth. Mike :D
 
Re: Fused disconnect vs Circiut breaker

Well you are not providing enough information. I will make a couple of assumption and by doing so you no what that makes me!

1. The four occupants are in one building, (same Building)
2. The fuse Disconnects are out side or.
3. The fuse disconnects are grouped inside.

Ex. 1 Is allows service entrance cables to be run to each of the separate occupants. Or group of occupants. In essence the service entrance is run outside (by code definition of outside) and terminates in a service disconnect when brought into the occupant?s service location.

If the fuse disconnects are grouped inside and feeders are run from a common area to each of the occupants then you cannot eliminate the grouped service disconnects.

If the fused service disconnects are grouped outside and the feeders are run through the interior of the building to get to the respective occupants you cannot eliminate the grouped disconnects.

I look at it this way you have to be able to go to one location to disconnect all the power in any portion of a building your in.

If the service entrances are considered out side by code definition then you do not need a service disconnect until the service entrance enters the occupant?s service location. And in your case this would happen four times for each of your four respective occupants.

[ February 22, 2006, 02:11 AM: Message edited by: david ]
 
Re: Fused disconnect vs Circiut breaker

david, Lets try again with a little more info:
(1.) Yes, the 4 tenants occupy an approx. space of 25' each in a 100' building.
(2.& 3.) The fused disconnects are NOT grouped together and are located INSIDE the building or each space.
If the service entrances are considered out side by code definition then you do not need a service disconnect until the service entrance enters the occupant?s service location. And in your case this would happen four times for each of your four respective occupants.
Click to expand...
All 4 sets 3/0 sevice feeders to each space (1 set per space) come from an 800amp CT Cabinet and are outside the building. They then come up from the ground on the wall to a poco meter outside. From that meter they go into each space to a fused disconnect, then to a MLO 42ckt panel.

My question was about the fused disco in the building. I think I'm reading 230.90 (A) ex.2 to say that a Circuit Breaker can be used to protect these feeders. In that case the disco could be eliminated and Main Breaker 42ckt. panels could be installed.
The above quote by david is it. Hope this clears up any assumption there might be. thanks Mike :D
 
Re: Fused disconnect vs Circiut breaker

why not go from the transformer to a 4-gamg commercial meter module, each meter with 200Amp c/b and feed each tenant w/ a MLO panel. The meter module can be installed outside or inside of the building.
 
Re: Fused disconnect vs Circiut breaker

Ignoring everything else, especially the meters.

You are asking if it is less expensive to provide and install a single main breaker panelboard instead of a seperately mounted main switch which then feeds a main lug only panel.

IMHO, yes.
But, have you considered why it was originally designed as seperate items?
Sometimes it is done because the designer incorrectly feels that only the service entrance equipment needs to meet 110.9. In other cases the designer is purposely using seperate components in order to have a series rated system per 240.86.
 
Re: Fused disconnect vs Circiut breaker

Originally posted by bwyllie:
why not go from the transformer to a 4-gamg commercial meter module, each meter with 200Amp c/b and feed each tenant w/ a MLO panel. The meter module can be installed outside or inside of the building.
Click to expand...
Expecting a return call from the Arc/Eng. that is requesting all that equipment. Looked into the commercial module which I like better because it will group all the 200a cicuit breakers in one location and save about $3,000. Let ya know what the results are. Thanks
 
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