[wendon]

Power is limited to an existing apartment. To be granted all the proposed loads by the building management, we must install a switch or relay of some kind that will prevent the use of an air conditioning unit while the oven is in use. The load is 208v 30 amp.
Any idea what I can install to make this automatic.

If you want the oven to have priority it's probably possible.

 

[oliquir]

only way i think is you put CT in a panel that monitor loads then you activate a contactor that shutdown the air conditionning

you could use one like this that detect if oven is on
http://www.automationdirect.com/adc/Shopping/Catalog/Sensors_-z-_Encoders/Current_Sensors_%28AC_-a-_DC%29/Current_Switches_-a-_Indicators/Single_Range_AC_Current_Operated_Switches

 

[McClary’s Electrical]

Use generacs load shedding modules.

 

[Meadow]

My first thoughts are upgrade the service. This sounds like a problem waiting to happen. It actually might be cheaper to just upgrade and do without the extras.

But in any case, if you were to do a load interlock cheapest and simplest would be a double pole double throw Allen Bradley contactor and a switch located in the kitchen. Switch would engage it transferring load from the AC to the oven. Doing this to be automatic gets complicated. The technology exists, they make the relays, but its not cheap unless someone knows of something more economical.

My question is the oven also a 30 amp rated unit? Does the oven have clocks? If no to both your good to go from that point on, however most oven I have seen require a 40amp breaker, so the AC would need fuses in its disconnect. At the contactor if your dealing with #10 from that point on.

 

[daveEM]

I have the same problem with a condo project (250 units). My biggest problem is that the local handyman (retired Linesman) has connected (at least I think it was him) probably 50 units. He has since passed.

^^ They all seem to work fine.

Now I (the dork electrician) tell the owners of the other units wanting them that they can't have the air conditioners. The Code won't allow the additional draw on the 60 amp mains.

So they go out and buy two R2D2 air thingies and plug them in.

 

[McClary’s Electrical]

Use a butterfly interlock between the two breakers.

 

[micromind]

A current switch would work for this.

I use them to monitor whether or not a motor is actually drawing current, and the signal is sent to a PLC, but it could be used here as well.

Simply run one of the hots supplying the oven through the CT, and use the NC contact to power a relay that will cut power to the A/C whenever the oven is in use.

 

[wcord]

Guess I must be old.
Prior to the 70s, they used to install Load Misers on the stove circuit. It would give the stove priority over the other load ( usually the dryer).
And they still make them

here's your link

http://acdandy.com/products/dandy-load-miser-energy-divider-controller/

 

[micromind]

Guess I must be old.
Prior to the 70s, they used to install Load Misers on the stove circuit. It would give the stove priority over the other load ( usually the dryer).
And they still make them

here's your link

http://acdandy.com/products/dandy-load-miser-energy-divider-controller/

That looks a lot like what I described, but all in one box.

I'm pretty sure this would work for the OP, plus it's automatic.

 

[RIVETER]

Power is limited to an existing apartment. To be granted all the proposed loads by the building management, we must install a switch or relay of some kind that will prevent the use of an air conditioning unit while the oven is in use. The load is 208v 30 amp.
Any idea what I can install to make this automatic.

I did a similar thing in an apartment complex some years ago and the inspector went for it. What I did was to install a switch...Double pole, Double throw, Center off, switch. I believe that they cost around $35.00 each at the time because of the amperage. In that case I was separating the AC load from a resistive room heating load.

 

[bobelectric]

Who's the landlord, Fred Mertze?

 

[Auselect]

Upgrade to gas

 

[Meadow]

Who's the landlord, Fred Mertze?

:laughing:

More like Bernie Madoff. I have seen interlocks only in the biggest slums.

 

[Meadow]

I did a similar thing in an apartment complex some years ago and the inspector went for it. What I did was to install a switch...Double pole, Double throw, Center off, switch. I believe that they cost around $35.00 each at the time because of the amperage. In that case I was separating the AC load from a resistive room heating load.

What was the inspectors reasoning behind that? I cant imagine a building that heats and cools at the same time

 

[RIVETER]

What was the inspectors reasoning behind that? I cant imagine a building that heats and cools at the same time

It was an outlet that supplied a resistive heating unit and I converted it to also power a window unit air conditioner. The inspector just wanted to make sure that the two loads were not allowed to come on at the same time.

 

[Meadow]

It was an outlet that supplied a resistive heating unit and I converted it to also power a window unit air conditioner. The inspector just wanted to make sure that the two loads were not allowed to come on at the same time.

:laughing: Unless he was thinking something else might get plugged in...but still

 

[RIVETER]

:laughing: Unless he was thinking something else might get plugged in...but still

If they plugged another 220 volt appliance with the same configuration receptacle...yes they could.