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#176358 - 03/30/08 07:15 AM size service?  
gerard costa  Offline
Junior Member
Joined: Mar 2007
Posts: 10
Waterford, Connecticut
a modular home co. has wired a 3 fam home with three 200 amp panels hanging in the basement and a 100 amp owners panel too. each unit is about 11oo sq ft and the biggest draw in ea. unit is the kitchen which will have: micro, full oven, DW, HW heater and 2 sm app. so ea, panel has like 8 cir. and the owners has some lighting. a 200 amp service should be fine but splitting it up and bringing 60 amps to ea. 200 amp panel will look odd. is that the norm or what should it properly look like? it is in the state of RI and was pre wired from PA.

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#176366 - 03/30/08 11:24 AM Re: size service? [Re: gerard costa]  
JValdes  Offline
Joined: Jun 2007
Posts: 301
South Carolina
Why would the manufacturer install 3 200 amp panels and one 100 amp panel if they did not intend them to be used. I would contact the manufacturer and get their reasoning for these panels.
Check with POCO also and see if the service is maxed out for 200. If not you may be able to make the tenants panels 100 amp along with the owners panel. But I would still question the reason 3 - 200 amp panels for this load.
If they are all together, bond all panels to the electrodes and piping and wire each panel for the current of the main breaker. Do some reserch before proceding.

#176370 - 03/30/08 12:06 PM Re: size service? [Re: JValdes]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,142
You haven't really told us enough for an answer. Is there a community laundry on the house panel? What is the HVAC load?
Are all three panels connected to the service directly? (4 grouped disconnects).
Unless I am missing something from baby fatigue (possible) I think each panel must be served at 310.15(B)(6) ampacity based on the disconnect breaker size.

Greg Fretwell

#176407 - 03/31/08 04:42 PM Re: size service? [Re: gfretwell]  
gerard costa  Offline
Junior Member
Joined: Mar 2007
Posts: 10
Waterford, Connecticut
hey thanks for the feed back so far. to update the questions the manufacturer was charging the GC the same price for 100 or 200 so he had them put in the 200 amp panels thinking bigger. if he talked with me first we could have changed this. No community laundry each apt has it's own, sorry forgot to mention that. there is no AC shown, the heat is supplied by owner's funace which i guess will be pro-rated into the rents. I haven't seen the dwelling yet this was thrown at me from the GC and it raised a flag as soon as he said that the panels were 200 amp and 100 amp for the owners. so i told him that it wasn't the way i would have wired it but i'll get back to him with a price. it's being delivered some time next month.

#176410 - 03/31/08 06:46 PM Re: size service? [Re: gerard costa]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,142
A quick calc the way I see it
1100 sqft @ 3va 3300
kitchen/laundry 4500

3000 @ 100% 3000
4800 @35% 1680 Gen Lighting 4680va

Gen lighting 4680
water heater 5000
stove 8000
MW 1000
DW 1000
18680 @ 230v 82 amps per apartment
4 apartments 328a

I believe there are some diversity breaks you get on a 4 plex but without looking, this is not far off before you add the "house" load.
It sure sounds like a 400a service to me, maybe more simply because you gave each owner 200a. They start thinking hot tub and stuff when they see that big empty panel.

Greg Fretwell

#176412 - 03/31/08 07:13 PM Re: size service? [Re: gfretwell]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,142
Sorry, I missed the 3 and was thinking 4 units. That is still 246a

Then add the house load. I am guessing at least 5 tons of AC in a central system and probably more.

Greg Fretwell

#176435 - 04/01/08 03:15 PM Re: size service? [Re: gfretwell]  
EV607797  Offline
Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
I'm curious about the HVAC as well. In Rhode Island, and with a 100 amp owner's service, I'd assume that the central heat is gas. In New England, that usually means a hot water boiler. Then, that type of heating system is hard to accomplish in modular construction. What about A/C? I know that it is still common to build new construction in New England without air conditioning, but that's not quite as common as it used to be.

Could the reason for the 200A services to each unit be due to the fact that each one will have it's own heating system furnished and installed locally? If it is intended to be a heat pump with electric backup, the service sizes might make a little more sense.

Sorry to be providing more questions than answers. Something just seems to be missing.


"But the guy at Home Depot said it would work."

#176445 - 04/01/08 07:59 PM Re: size service? [Re: EV607797]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,142
I didn't think anyone had toaster wire heat up there. That would certainly add 10kw per unit. It's what I have in South west Fla and it doesn't really get cold here.
When I was across the river from Ed (So Md) I tried a heat pump and it was really spotty. When it was cold outside it just didn't work without strip heat.

Greg Fretwell

#176452 - 04/02/08 12:12 AM Re: size service? [Re: gfretwell]  
KJ  Offline
Junior Member
Joined: Nov 2001
Posts: 52
I do a lot of modulars here in mass.and usually they come from the factory with 200 amp panels.
no special reason, i do not believe they take into consideration load calcs,
think hey just put em in and ship em.

I agree that you will have to do the load calc for the entire building, and size your main accordingly, feeding each unit to full 200a cap.

#177698 - 05/10/08 07:39 AM Re: size service? [Re: KJ]  
mikethebull  Offline
Joined: Mar 2007
Posts: 100
Rhode Island
A 200A service with a 4 gang meter socket would have been sufficient. Then put 3-100a panels for the 3 apartments and 1 for the house panel. That is generally how we do it in RI. That is if it is gas heat. And the A/C considered are window units that the tenant supplies and is responsible for.

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