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Posted By: schenimann Residential load calculation question - 11/05/11 10:12 PM
I am bidding a new custome home. It is app 7500sf. My load comes to about 130amps without any hvac. They are going to do geothermal with supplemental heat strips. I just don't know what size. But even at 10kw that still is well under 200 amps. There is also a pool and framing provision for a future elevator. I am not bidding either of these yet because they are not sure what thay are doing for heat. All this being said, do I need to bump up the service. I would probably be pushing a 200amp service once everything is in with no provisional space.

Most houses I wire a smaller. You put on a 200amp meter and your good. This one is making me think. Do you step from 200 to 400amps?

This is a large house to wire. I do wire houses but few on this scale and even less bidding competitively. I know the guys I am bidding against. They are veteran residential electricians who do quality work. I just want to make sure that I am doing it right. I don't think it is a house that will go to the lowest bidder but to the best overall quote. Thanks, my dinner depends on it.

Side question: What is the best way to do outlets in the baseboards. Nail ons with box extenders?
Posted By: sparkync Re: Residential load calculation question - 11/05/11 11:11 PM
Personally, I think I would go ahead with a 400 amp if it's that big of a house and you are already getting close to the limit. IMO a house that big will probably want something more in the future. I would guess the other contractors are thinking the same thing. Better to give quality now than to suffer for it later. Just my opinion.
As far as the outlets in the baseboard. Is that what they are asking for? Unless it is, that's a whole lot of extra time and money, especially a house that size.
Posted By: gfretwell Re: Residential load calculation question - 11/06/11 12:49 AM
You said pool. Is that a spa too? Pool heat? Any of that will put you over.
Posted By: schenimann Re: Residential load calculation question - 11/06/11 01:52 AM
I bellieve it is a heated swimming pool and that they are going to use gas heat. Yes, they are calling for the outlets in the baseboards. What is the best way?
Posted By: KJay Re: Residential load calculation question - 11/06/11 02:08 AM
With a house that size, I think would also be leaning toward 400A minimum as well, before I even did the load calc. Especially when their already talking about a pool, elevator and will probably add some other unannounced future projects like a finished basement, pool house, heated two car garage, etc.
Sounds like they most likely have the resources to do things right anyway.

The best way to handle the baseboard outlets might be to just stub the wires out and let the carpenter drill a 3/4" hole in the center of the baseboard and leave them sticking out for you to cut in old work boxes after the baseboard is installed. Those Allied 9361-E, 16 Cu.In. NM old work boxes and a multi-cut tool like the Rockwell Sonicrafter with a standard end-cut blade make pretty quick, clean work of that type of thing these days.
Posted By: gfretwell Re: Residential load calculation question - 11/06/11 02:23 AM
Are baseboard outlets coming back? I always assumed they were just the way old time electricians installed circuits in a house that never had electricity before without cutting into the plaster. I have only seen them in very old houses around DC.
They always seemed to look "beat up" to me from vacuum cleaners and furniture legs. I assumed that is why we see them a "hammer handle" off the floor now.
Posted By: schenimann Re: Residential load calculation question - 11/06/11 03:19 AM
I was leaning toward the 400a. Thanks for the confirmation.
I think the baseboard outlets are an architectual detail that looks nice but not cost effective. The sheetrock rock work is cheaper than the trim work.

Should I cut the holes or give the trim guy a template and let him cut them? I always like the less cutting and trim work that I need to do.
Posted By: HotLine1 Re: Residential load calculation question - 11/06/11 03:28 AM
Greg:

Apparently 'bb outlets' are now an "in" thing. There are two 8k SF in progress here both with 'bb' outlets.
Posted By: gfretwell Re: Residential load calculation question - 11/06/11 05:17 PM
What is old will be new again I guess. I guess leisure suits and bell bottoms are in our future.
Posted By: KJay Re: Residential load calculation question - 11/06/11 06:18 PM
I also believe that it’s mostly an architect thing in the larger homes. They apparently don’t like the look of our receptacle outlets in the walls. I guess I do kind of like the look of them being installed horizontally in the baseboards, but I also think it’s a pain to have to always squat down on bended knee every time you want to plug something in. I’m going to assume that in situations like these, hired help will likely be doing most of the bending and squatting for the homeowners anyway.
As bad as it seems for installing electrical outlets, I think it would an even bigger pain installing central vac hose type inlets and aligning the associated piping and wiring within the baseboard.

I always operate under the premise that the less contact other trades have with my wiring, the better off things are. I’ve had ham-handed carpenters take it upon themselves to cut in the baseboard receptacles before, without consulting me first, and they were a disaster. Undersized metal boxes they picked up at the hardware store, holes cut so big the ears were just floating so the screws wouldn’t hit wood, NM behind the boxes in the wall pinched and folded like pipe cleaner, NM sheathing ripped and damaged conductor insulation. It basically turned into even more of a pain for me, because I had to first undue the damaged they did before I could begin to make things right.

Go with the 400a service, no doubt something will be added. With all that floor space 10kw may be a little light for a guess on heat strips anyway. As far as baseboard outlets, if you can(do) use plastic boxes, carlon makes an adjustable one with a metal bracket. I used close to 100 of them on the last house I did, you can put em in fast, let the carpenters cut the trim around them, then adjust the depth after the trim is up. A word of caution, Romex also makes a box that is adjustable, but not nearly as easily once the trim is up, take a look at both and the difference is easy to see.
Posted By: Tesla Re: Residential load calculation question - 11/07/11 04:06 AM
BB outlets are not compliant with the Disabilities Act.

They are too low.

I'm amazed that they didn't get stopped at plan check.

Federal law stipulates that all switches stay below 48" AFF and that receptacles stay above 12" AFF. These are the limits faced by anyone in a wheel chair. They apply to all general use switches and receptacles.

I doubt there is an exception for residential construction.

By your statements that is what we're talking about.

I'd ask them how they can get around the Americans with Disabilities Act.

Get back with us when you have a response.
Posted By: SactoCliff Re: Residential load calculation question - 11/07/11 04:17 AM
The ADA does not apply to residences.

Commercial, institutional, etc., yes. Not to private homes.

Not to say that it's not a good idea to install receptacles high and switches low. We're all gonna get old (if we're lucky).

Cliff
I see a lot of baseboard receptacles in the new houses that I inspect. I think another reason for BB recpt. is that so many people are putting up chair rails and decorative moldings and there is nothing worse than trying to put up molding with a receptacle right in the way. So by having them in the BB, you don't have those problems.
"Federal law says ..."

Just a reminder to check your assumptions, see what the law REALLY says.

Not only does the law NOT apply to residential work, it also does not apply to most commercial / industrial locations.

Most telling of all, the various artwork and specifications you see are NOT the Federal requirements- even though they're published as part of the CFR. They're specifically described as non-mandated guides in an appendix.

Alas, if you do commercial work, many times these 'suggestions' are included as mandatory job specifications.
A reminder regarding 400-amp services ....

There are two types. One is a true 400-amp service, with a current transformer. The other is really a 320-amp service{ that is, a 320-amp meter base that can handle surges to 400 amps.

If your load calculations exceed 320 amps, you get to put in the more expensive CT-type service.

Talk to the PoCo; Our OP might be able to simply install a trough with provision to add more meters / services to serve the future additions.
Posted By: ghost307 Re: Residential load calculation question - 11/07/11 08:20 PM
I'd recommend tha 400A service, if only to keep from being the guy blamed when the elevator gets added and they have to upgrade the new electrical service.

I hate being called names...even in absentia.
Posted By: schenimann Re: Residential load calculation question - 11/18/11 03:50 AM
I turned in the bid for the house. Thanks for the help. Next question: They are wanting to add a 20kw gen to the bid. I have only installed 16kw and smaller on a 200 amp service. What is the best set-up for this on the 400 amp service?

They are also possibly looking at LED 6" cans(about 100). Any input?


Posted By: ghost307 Re: Residential load calculation question - 11/18/11 03:44 PM
You're probably looking at recircuiting the loads that they want on the generator to a separate panel. That way you can use an ATS sized to the generator. If they want the whole place on the generator (even if they turn most everything else off) you will need to install a 400A ATS.

If the former, I'd figure it as a new service panel, generator and the smaller ATS.
If the latter, I'd add in a 400 A ATS with the generator and plan on spending a lot of time explaing how much of their new house will and won't be able to powered during an outage.

As to the LED downlights, I've only used the Juno product, but I think that they're all still working the bugs out of the technology...otherwise all of the major manufacturers would be offering them. If you get an off-brand, be sure to check out the UL Listing in case the AHJ wants to hold your feet to the fire on it.
Posted By: knowledge Re: Residential load calculation question - 11/21/11 11:11 AM
well why wont the 320 amp service be enough or adequate
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