I am replacing an old single-phase AC unit with a new 60,000 BTU three-phase inverter unit. 

 

The specs say the running current it 11.5 amps. 

 

What size service/breaker is appropriate?

 

I'm thinking 20 amps should be okay, but I would feel better with conformation. 

 

Also, the run is about 12m from the breaker to the condenser. 4mm^2 copper should be fine, yes?

2 hours ago, Yellowtail said:

I am replacing an old single-phase AC unit with a new 60,000 BTU three-phase inverter unit. 

 

The specs say the running current it 11.5 amps. 

 

What size service/breaker is appropriate?

 

I'm thinking 20 amps should be okay, but I would feel better with conformation. 

 

Also, the run is about 12m from the breaker to the condenser. 4mm^2 copper should be fine, yes?

That's 11.5A per phase?

I think the 3 breakers are 11.5A plus 20%.

I would use as thick a copper stranded cable as is possible to reduce voltage drop.

30 minutes ago, carlyai said:

That's 11.5A per phase?

I assume. The literature was not clear.

30 minutes ago, carlyai said:

I think the 3 breakers are 11.5A plus 20%.

So 20 amp should be fine?

30 minutes ago, carlyai said:

I would use as thick a copper stranded cable as is possible to reduce voltage drop.

Thanks, but I do not know what that means. I thought 4mm^2 was good. Are you saying I need heavier than that?

The spec. will be 11.5A per phase running current, an inverter unit has no startup surge so no need for an over-size breaker.

 

Unless the manual says otherwise an 11m run of 2.5mm² cable (4 cores plus ground) on a 20A 3-phase breaker would be my choice. The manual would trump those values.

 

Bigger is of course no problem if you already have the cable.

 

 

2 hours ago, Crossy said:

The spec. will be 11.5A per phase running current, an inverter unit has no startup surge so no need for an over-size breaker.

 

Unless the manual says otherwise an 11m run of 2.5mm² cable (4 cores plus ground) on a 20A 3-phase breaker would be my choice. The manual would trump those values.

 

Bigger is of course no problem if you already have the cable.

 

 

Thanks, I don't have the manual or the air conditioner yet, I was just looking at the spec sheet and wanted to get he service correct before it gets here. 

We're getting our 3-phase and new panel installed starting tomorrow.

 

Two days running the new wire and what not. 

 

Approval for the changing poles

 

Then two days for the pole & meter change and the panel -swap. 

 

Wish me luck!

They showed up this morning and are starting. 

 

Here's the before:

 

    

Are you without juice whilst they work, or have they at least kept some lights and the freezer on?

 

We are supposed to have power except for about four hours, on the last day when they cut in the new meter and install the new panel.

 

The existing service comes from a pole across the street from the front of the house.

 

The new service comes from a pole across the street from the back of the house.

 

Once the new panel is hot, they'll pull the old wire and meter down 

A number of delays, but they were back Monday and it is moving along. Tomorrow they are supposed install the new panel, install the new 3ph meter and cut it in. Supposed to be without power about four hours. Wish me luck!

..

Finally got my meter: