Is the outside Pull Out Disconnect box, next to the outdoor AC heat exchanger, necessary?

[Robert Gift]

The air conditioner is working fine.
Wanted to disconnect power before removing the fan and cleaning leaves whichad fallen inside the heat exchanger.

Opening the Cutler-Hammer Pullout Disconnect box, the ON/OFF handle is pulled out and turned 180º and reinserted to disconnect the 240V power.
It powers the outside refrigerant pump and fan of theat radiating coil unit.

The disconnect handle could not be pulled out. PLASTIC MELTED!

Apparently where one of the two Bussmann® 60-amp fuse end fits into its top "C" holder, much heat was created and melted the nearby plastic. The fuse case was brown from internal heat but the fuse element was still intact.
Sand-like material fell out of the fuse tube. The fuse metal cap remained in the Disconnect's holder.

I bypassed the Disconnect by connecting the two 10(?)-gauge White wires together and two Black wires together with big wire nuts.

Need I replace that Disconnect box?
The outoor circuitbreaker panel is only 12 feet away on the same wall.

Shall try to attach photos.

Thank you.

Suspect a defective fuse because the other fuse is fine.

 

[WorthFlorida]

Replace the cutout, it could be confusing what breaker is for the condenser unit and air handler, besides it's usually code. Cartridge fuses use sand for a slo blow rating? Any idea why it was all burned? Might have been blown from a past ac unit.

Next time just pull the handle. Do not insert the blade upside down as it's already off. The idea is too indicate by the label it's off. Some techs will pocket the blade so no one else can insert it.

 

[Sponsor]

 

[wwhitney]

Need I replace that Shut Off box?

Yes, it is required to be in sight of the HVAC unit per NEC 440.14.

Also, depending on what the label of the HVAC unit says, the HVAC unit may require protection by fuses, rather than by a circuit breaker, so relying on an indoor circuit breaker would not suffice.

If the HVAC nameplate does permit a breaker, you could get an enclosed circuit breaker instead of a fused pull out disconnect, if you prefer.

Cheers, Wayne

 

[Fitter30]

Other than electrical code means of disconnect within 50' and line of site, the way to disconnect high voltage for service and washing the coils. Number 1 reason for me keep unqualified from electrocution, doing something stupid not killing the power. Under $25 at a box store.

 

[Robert Gift]

Yes, it is required to be in sight of the HVAC unit per NEC 440.14.
Also, depending on what the label of the HVAC unit says, the HVAC unit may require protection by fuses, rather than by a circuit breaker, so relying on an indoor circuit breaker would not suffice.
If the HVAC nameplate does permit a breaker, you could get an enclosed circuit breaker instead of a fused pull out disconnect, if you prefer.
Cheers, Wayne

The fused pull-out disconnect is $24 and requires two Type H fuses $26. (The previous fuses are 60-amp.)
The non fused pull-out disconnect is $12.95.

Why TWO fuses in th 240-VACircuit? Is there a path to ground between the 120-Volt White and Black legs?

Thank you.

 

[wwhitney]

How about a picture of the nameplate of the outdoor HVAC unit supplied? It should list things like MCA (minimum circuit ampacity) and MOCP (maximum overcurrent protection).

Why TWO fuses in th 240-VACircuit? Is there a path to ground between the 120-Volt White and Black legs?

To the second question, yes, always for a grounded service, like all US residential services. (The white leg should be relabeled red or any non-white color). Each leg is 120V to neutral, which is grounded.

So if one leg faults to ground, the other leg won't see current. That's why each leg needs its own fuse when using fuses as the OCPD.

Cheers, Wayne

 

[Robert Gift]

Thank you.

Rheem RAKA-060JAZ Mfd. 6-2000

Compressor R.L.A. 28.9/28.9 L.R.A. 175

Minimum Suppy Circuit ampacity 39/39 amp
Maximum Fuse or Circuit Breaker Size 60/60* amp
Minimum Fuse or Circuit Breaker Size 50/50* amp *HACR type Breaker for U.S.A

The Buss fuse element appears to have gotten hot inside its metal cap where it attaches to the cap.

The heat distorted the Pull Out Disconnect's plastic around where the fuse inserted into the Disconnect's C-shaped fuse contact.
The fuse element is fine. No discoloration until it gets close to its cap.

Shall try to attach photos.

Thank you.

 

[wwhitney]

Maximum Fuse or Circuit Breaker Size 60/60

Since the unit nameplate says "fuse or circuit breaker" if your disconnect is supplied by a 50A or 60A circuit breaker, that suffices as branch circuit OCPD. In which case you may replace your disconnect with an unfused disconnect.

On the other hand, when you replace the unit, there a good chance that the new unit will have a smaller MOCP. In which case if you have a fused disconnect, replacing the fuses would be easier than changing the circuit breaker.

Cheers, Wayne

 

[Robert Gift]

Since the unit nameplate says "fuse or circuit breaker" if your disconnect is supplied by a 50A or 60A circuit breaker, that suffices as branch circuit OCPD. In which case you may replace your disconnect with an unfused disconnect.
On the other hand, when you replace the unit, there a good chance that the new unit will have a smaller MOCP. In which case if you have a fused disconnect, replacing the fuses would be easier than changing the circuit breaker.
Cheers, Wayne

Thank you.

Fortunately, the new Non Fuseable Pull-Out Disconnect box components perfectly fit the old box.
Otherwise wife would want me to painthew box to match the old box when the house was recently painted.

Buss should pay for the box since their 24-year-old fuse got so hot where the element connects inside the fuse cap.