Replace Main service switchboard

[anbm]

We are to replace one main service switchboard (fed out of utility xfmr) in one building by a new switchboard. The new switchboard shall be located in new central plant across from old building. We will back-feed all exiting panels in old building from new switchboard? What is the best way to accommodate this with min. power interruption time?

Should we add a new utility xfmr on site and feed new switchboard from this xfmr first before disconnect and re-feed existing building?

The new utility xfmr maybe same size as old one that currently feed this ld switchboard... so it may not a cost saving but can eliminate power shutdown time to the building. Thanks!

 

[charlie b]

We will back-feed all exiting panels in old building from new switchboard?

If I understand what you are saying, then I would say this sounds like a violation of 225.30. Do you meet any of the special conditions? 225.30(E) is a possibility, perhaps, depending on the type of facility.

 

[anbm]

I should not leave the question mark there. Let's try it again:

We want to replace an existing main service switchboard 'MSA' in the building by a new switchboard 'MSB' and re-feed all panels downstream of existing switchboard from new switchboard 'MSB'. The new switchboard 'MSB' will be located in new central plant across from old building.

In order to do this, since we can't shutdown existing - main service switchboard 'MSA', I guess we have to install a new utility xfmr, from this xfmr we feed new switchboard 'MSB' first, then from new switchboard 'MSB' we bring all required conduits to old building and re-feed all panels that are currently fed out of old switchboard 'MSA'. We can re-feed one panel at a time to minimum power shutdown time.

Once all panels are completely re-fed from 'MSB', we can remove existing switchboard 'MSA' and its upstream utility xfmr.


Any other options that cost less? I would like to keep existing utility xfmr that feeds 'MSA' and re-use it to feed 'MSB' but not sure how...without shutting down power to the whole building.

 

[JWCELECTRIC]

Why are you relocating the new switchboard MSB into a new building? and what size service do you have?

 

[charlie b]

Let's try it again:

Fair enough; I will try again as well.

225.30 says that when you feed power from one building to another, you can only do it with a single feeder or branch circuit, unless you meet one of the five conditions. It appears to me that you don't. Therefore, you cannot have separate circuits feeding loads in building A from new switchboard MSB. It is a code violation, plain and simple.

Or am I missing something in your description?

 

[Cold Fusion]

...Or am I missing something in your description?

I hope so.

...225.30 says that when you feed power from one building to another, you can only do it with a single feeder or branch circuit, unless you meet one of the five conditions. It appears to me that you don't. Therefore, you cannot have separate circuits feeding loads in building A from new switchboard MSB. It is a code violation, plain and simple. ...

The OP sounds bigger than small commercial. So once past that, then:

Every industrial installation I've worked on qualifies under 225.30.E.

A few qualify under 225.30.C - and a few under 225.30.B..2

Most qualify under 225.30.A.6 - But these are mostly double ended subs. And that likely is not the scenerio here.


cf

 

[Cold Fusion]

anbm -
Well, you never asked if your intended installation design was a good idea or not. You simply asked if there was cheaper way to do the temp power for the construction part, while minimizing the outages.

So, answering that only:
For minimum outages, I can't think of much else you can do.

cf

 

[charlie b]

Every industrial installation I've worked on qualifies under 225.30.E.

That is why I suggested it in my first post. But even if it does apply, I would not recommend invoking it.

A few qualify under 225.30.C - and a few under 225.30.B..2

I don't think either of them apply here. This is about moving an existing power source, so I have to infer that the existing source did not meet either of those conditions.

 

[charlie b]

So, answering that only: For minimum outages, I can't think of much else you can do.

I agree. The process you described should give you the minimum down time.

 

[Cold Fusion]

...But even if it does apply, I would not recommend invoking it. (225.30.E - cf)

Why is that? The exception is there for a reason - Industry uses it plenty. In fact I would call it the norm.

cf

 

[anbm]

Fair enough; I will try again as well.

225.30 says that when you feed power from one building to another, you can only do it with a single feeder or branch circuit, unless you meet one of the five conditions. It appears to me that you don't. Therefore, you cannot have separate circuits feeding loads in building A from new switchboard MSB. It is a code violation, plain and simple.

Or am I missing something in your description?

Yes, 225.30(E) also 225.31 , 225.32 Exception 1.

 

[anbm]

anbm -
Well, you never asked if your intended installation design was a good idea or not. You simply asked if there was cheaper way to do the temp power for the construction part, while minimizing the outages.

So, answering that only:
For minimum outages, I can't think of much else you can do.

cf

Another option is we can rent a temporary generator, sit outside and feeds 'MSB' when re-feed all panels downstream of 'MSA'. We may need a generator with huge belly tank (-:

 

[benaround]

Why is that? The exception is there for a reason - Industry uses it plenty. In fact I would call it the norm.

cf

I don't agree with that at all. I see industry running a single large feeder to additional

buildings and if the building is large enough it gets a service for itself. Also, this is an odd

situation where they are using building #2 to feed building #1. I could see refeeding the

'MSA' gear from 'MSB', but, documented switching procedures are not going to work when

the fire fighters show up in the middle of the night. Industry has no more right to use 225.30(E)

than Mr. Homeowner does, anyone can make copies of switching procedures.

 

[Cold Fusion]

... documented switching procedures are not going to work when the fire fighters show up in the middle of the night. ...

benaround-
Documented switching procedures work just fine for my clients - yes, even in the dead of the night.

Generally speaking, the Fire Marshals want to see the procedures. They generally go over the installation, marking up their copies of the ground plans. They want to know locations for hazardous wastes, flamables, chemical storage.

Nearly universally, the fire departments will not enter an installation without a guide. They will sit right at the gate and let the installation burn before they will enter and foolishly endanger their crews - as they should.

...Industry has no more right to use 225.30(E) than Mr. Homeowner does, ...

This one suprises me. I did not know this. I guess it never occured to that there was any similiarity in the policies for homeowners and industry.

... anyone can make copies of switching procedures.

That's true, but why does that matter? Copies or not, they still have to fit the specific installation.

Perhaps you should consider changing your clientele.

cf