Complicated Generator Installation......

[Seven-Delta-FortyOne]

I have a multi-unit residential project (4 units).

All gas WH and cooking, but 2 units have electric clothes dryers, and 2 units have hot tubs.

Fridge, microwave, DW, furnace in all units.

Just for major appliances, not counting lighting load ( all LED, pretty minimal) and SABC (these are VRBO units, so owner supplies a coffee maker and that's it), I'm coming up with around 60kW GenSet.

Split service drop, so 2, 400A ATS will be required.

If I eliminate the hot tubs, that would help a huge deal. AHJ does not require us to do a full Article 220 load calc, (at least not on basic residential, they may on this one), I could probably get away with a 32kW, or at least a 38, with 200A ATS.

The Generac power management systems, well, I haven't heard much good about them.

So I was considering coming off the load side of the main breaker, installing a small box with a 15A breaker, and running a control wire to a 50A NC contactor in line with the hot tub feeder. Take the hot tubs off-line when utility power goes down.

Am I overlooking an easier solution?

 

[brantmacga]

I would use the generac load shed modules and be done with it. I’ve had one fail within the last few years, and it happened within a week of install. I would also likely opt for the 100A load shed module of these are 50A hot tubs.


Also, how many meters do you have? If it’s four, then you are going to need four transfer switches.

 

[Seven-Delta-FortyOne]

Advantage to that is he can just run everything, and the customers can use the hot tub while it’s pouring rain and trees are falling down.

The meter system is kind of….different.

There is a 200A main disco, with N-G bond, then a can with bus bars, then the meters.

I had originally planned to intercept the feeders in the can, but that would make the meters run while on genny power.

 

[brantmacga]

How many units are on each meter?

Why are there two meters downstream of another ?

 

[Seven-Delta-FortyOne]

One unit per meter.

Meters are all parallel. Hard to see in the pic, but there’s a nipple into each meter can.

 

[curt swartz]

I would start by telling the customer that entire service needs to be rebuilt. I can't believe PG&E connected it and set meters with the main breaker ahead of the 3 meters.

 

[Seven-Delta-FortyOne]

It’s certainly a weird setup. I’ve never seen one like it.

That large can does not even have the poco tabs on it.

The service drop is, uh, different.

They paralleled the drop from the transformer, then combined them at the weather head.

And there is one drop that combines 2 different addresses, and it appears that the feed to that house down the road goes under the first house.

 

[hillbilly1]

I would start by telling the customer that entire service needs to be rebuilt. I can't believe PG&E connected it and set meters with the main breaker ahead of the 3 meters.

I’ve seen it done with three phase 480, it’s called cold sequence metering, usually when CT’s are not used, but direct metering. But I haven’t seen it done with single phase.

 

[mopowr steve]

Man, I certainly wouldn’t connect the bottom disconnects feeder neutral to the EGC bar!
And I believe with the disconnect on the line side of meters, it would be a “meter equipment disconnect” not subject to having to run a separate EGC and neutral to the meter bank. Although I’m not sure if that meter bank has a floating neutral or not.

 

[Seven-Delta-FortyOne]

I wasn’t very clear, but the second set of pics is the second house, where the fourth meter is, plus a meter for the house down the road.

In the first set of pics, where the large can is feeding the three meters, N/G bond is proper.

It’s bonded in the first 200A disco, and the GEC that you can see in the pic is ran through the can and into the other discos, where it is separated

That part of the install at least is proper.

I’ll price out running 4 separate gennys vs running one large one. Needs 4 ATS anyway.

I’ll do a site visit tomorrow and see how feasible it will be to tap those three units after the meters. Not a lot of wall space left.

I believe using outside feeder tap rules, I can install 200A ATSs, even if I go with a 60kW genny.

 

[Charged]

My local utility has an exhibit where they show the requirement for a main with associated requirements for Multi tenant services 6 or more. I think it coincidentally aligns with the NEC requirement but I always figured it was like the cold sequence 480 requirement they also have. I would size and indicate the contractor to provide and install but I never thought about ownership, I guess the utility won’t lock it or anything. Not sure how they treat the 480v cold sequence disconnect. Either way you do see this set up a lot with multi tenant devices , I think when it’s done with loose gear and not a whole meter bank piece of equipment it does make you think a little bit about the owners wiring ahead of the meters

 

[brantmacga]

this is a really strange setup. The only way I would do it is to demo all of that, and install 4 meters and 4 transfer switches.

 

[brantmacga]

also, I'm still confused on the 3-meter setup. Its labeled as 3058-1, 3058-A, & 3058-5. And you mentioned this is feeding two residential units.
So is 3058-1 some sort of check meter against the other two?

And yes, you could run (4)x 200A ATS off a single 60kw generator. I would take all that metering equipment of the wall, set a 3R wire way on the wall and install distribution blocks to parallel the generator feed. Install new service-rated transfer switches on top of the wire way.

Have a second wire way above the equipment for the service drop, and then drop down into new meter cans.

 

[Seven-Delta-FortyOne]

This one is feeding three units. No idea why they are numbered like that.

The other building has the meter for the fourth unit, plus a neighbors meter.

I would love to do it the way you have described, I will just have to put the bid together and see if he goes for it.

If I have room to just go in below the existing meters, that will probably be the easiest and cheapest though.

Im heading over there this morning I’ll get some more pics and info.

 

[brantmacga]

This is a crude sketch of how you could set that up

Sent from my iPad using Tapatalk

 

[brantmacga]

You'll size the feeders to each trough for the MOCP in the genset, then go from distribution blocks within the wire way out to each ATS.

 

[Seven-Delta-FortyOne]

This is a crude sketch of how you could set that up

Sent from my iPad using Tapatalk

That’s my plan if he goes for it.

 

[Seven-Delta-FortyOne]

Went back today and opened everything up.

One disco after the meter is bonded N/G, other two are not.

There very little access to physically run the conduit to the ATSs.

All I can do is submit the bid in a way that will work, and if he can’t do it, all I’ve lost is several hours of free labor.



My plan would be to mount 3 ATS basically under that window.

Fix the redundant N/G bond in the far left panel, figure out how to get 6 conduits over
to the ATS, and leave everything else as is.