Panelboards

[brad troxel]

A new one came up I haven't seen before. Typical 400A main service fused disconnect feeding a 400A MLO panelboard. This panelboard has top lugs and feeds another panelboard, except that first it feeds a 400A contactor which then feeds the 2d 400A panelboard. The 2d panelboard gets turned OFF if a certain condition is not met (along with all the equipment of course.) The 1st panel stays HOT all the time while the contactor switching the other panel off/on, if all that makes sense. I've never switch a whole panelboard off like that before, but I don't know why you couldn't. Kind of like a transfer switch, except nothing gets transferred.
thanks,
BT

 

[iwire]

Re: Panelboards

This is very common.

It can be done as you describe or the contactor can be located in the enclosure with the panel.

You can get split bus panels so that one half can stay on and the other half can be controlled.

Any place that has a large amount of lighting to control at the same time is a good candidate for a contactor controlled panel.

 

[luke warmwater]

Re: Panelboards

Some of them are even remote operated, such as Home Depot. They are controlled from Atlanta, GA., or at least they used to be.

 

[yanert]

Re: Panelboards

Hi Luke,

What is the stratagy of switching the lighting panel from a remote location, somewhere in another state as you suggested? It would seem that local control, timers, photocells, ect would be logical. Thanks.

 

[iwire]

Re: Panelboards

We do a lot of retail stores controlled as "luke' described.

Local control is exactly what the main office does not want.

Target, Filenes, Lord & Taylor, Neman Marcus, Home Depot, Walmart etc. all control HVAC and lighting remotely.

A light sensor is used to control the on time of the lighting within the time frame allowed by the main office.

Many times overriding the systems at the local location is not done easily and if I do say override the site lights during the day to work on them a phone call from the main office will be made to the store in order to find out why they are 'wasting' power.

HVAC system are another thing they do not want the local people adjusting.

If the store closes at 9 PM the control system may shut down AC at 7 PM and let the store 'coast' till close.

It is common to set the HVAC program up to turn on supply fans on early in the morning and pump the cool fresh morning air into the store to pre cool it. There will be indoor and outdoor humidity sensors to ensure the store humidity is controlled.

One large store I worked on literally turns all lighting and receptacles off when the store is empty. This includes exit signs and emergency lighting.

The emergency systems will come on when the fire alarm triggers or if the power fails.

Bottom line it is all about saving money.

Bob

 

[speedypetey]

Re: Panelboards

In the past I did alot of stores in local malls. Most all of the "chain" type corporate stores were set up like this. Some even had a 120/240 panel contactor controlled for non-critical 120 loads.

 

[peter d]

Re: Panelboards

Bob,

So when you are standing in line at the checkout, the panels next to the exit door is where all of the store lighting is controlled?


Edit to clarify: Standing in line at HD or Lowes.

[ February 26, 2005, 03:13 PM: Message edited by: peter d ]

 

[iwire]

Re: Panelboards

Peter not having been directly involved with any of the HDs I do not know for sure.

Here is my guess, no those panels do not run sales floor lighting.

The panels at the front end most likely provide 208/120 power for the checkouts, and for miscellaneous 120 loads in that area.

The sales floor lighting is most likely all fed right from the main electric room at 480 or 277 volt. Very little of the lighting (other than displays) will be less than 277 volt.

It is also possible they put a 480/277 panel at the front to power signs, canopy lighting and site lights. All these could be run through the same contactor for control.

Bob

 

[peter d]

Re: Panelboards

Bob,

Yes, usually there is a transformer hanging there with panels for both voltages, so that makes sense.

IIRC, there is a main bus duct that runs down the center of the store where all the ReLocs plug into for the overhead lighting, but I forgot what end it is fed from. I'll have to check next time I'm there, which is almost never.