No MCA or MOP on name plate

Dbronx

Senior Member
FLA, LRA Name Plate.JPG The name plate stetes 208 volts, 3 phase, 60 HZ FLA 37.8, LRA 156, the high LRA confuing. I figured 37.8 FLA could ues the for conductor sizing, 37.8 X 1.25 = 47.25 for conductor size 4 awg. 37.8 X 2.25 = 85.05 amps for overcurrent Device. this is where I loose it the LRA is 156 = in rush, should LRA be used for MOP??
 
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Mgraw

Senior Member
METLABS is a NRTL. That unit apears to be military. I would use #4 and an 80 amp OCPD. The tag calls for 5 wires.
 
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Dbronx

Senior Member
METLABS is a NRTL. That unit apears to be military. I would use #4 and an 80 amp OCPD. The tag calls for 5 wires.
So the way you caculated the conductor size was RLA 37.8 X 125%, and OCPD RLA 37.8 X 225%. Why is the LRA 156 listed on the name plate?
 

david luchini

Moderator
Staff member
yes made in the USA 208 volt 60 HZ. I would like to know if I'm caculating this correctly.
I don't think you are calculating this correctly. Doesn't this unit come with a cord and plug? I would suspect that is why there is no MCA or MOCP on the nameplate, because you need a branch circuit to match the unit's cord and plug.

If it didn't have a cord and plug, you'd need the fla's of each of the components in the unit to figure the proper MCA and MOCP.

From the info I found on the unit you have the following component amps:

Compressor..........23.0A
Evap fan...............3.8A
Cond fan #1.........2.0A
Cond fan #2.........2.0A
Heater..................33.3A
control ckt...........0.3A

Heating mode.......37.8A
Cooling mode.......31.5A
 
T

T.M.Haja Sahib

Guest
Dbronx;13 the high LRA confuing. .......... this is where I loose it the LRA is 156 = in rush said:
You need not bother about LRA,IMO.The protective device with MOP you calculated from RLA might be able to withstand the LRA.But check with the manufacturer for the size and type (fuse or breaker) of the protective device,anyway.
 

Dbronx

Senior Member
You need not bother about LRA,IMO.The protective device with MOP you calculated from RLA might be able to withstand the LRA.But check with the manufacturer for the size and type (fuse or breaker) of the protective device,anyway.
Again my limited posting has got the best of me, MANY THANK to every one who relpyed. I'll try to phone the manufacture and get back to you, I would like to shed some light on this subject for everyone interested. You referenced RLA but FLA was on the name plate I thought FLA was a larger value than RLA.
 

Dbronx

Senior Member
Again my limited posting has got the best of me, MANY THANK to every one who relpyed. I'll try to phone the manufacture and get back to you, I would like to shed some light on this subject for everyone interested. You referenced RLA but FLA was on the name plate I thought FLA was a larger value than RLA.

Sorry for the delay, I was down range. The manufacture recommends using the 37.8 FLA to size conductor and 125% of that to size over current device. That would mean 37.8 amps #6 AWG then 37.8 X 1.25 = 47.25 that would mean a 50 amp circuit breaker and 50 amps disconnect. There are a few things I picked up about air condition compressors and overload protection. The motor overloads are better at protecting the conductors than circuit breaker. The circuit breaker is better suited for ground fault and short circuit protection in this case. As far as the inrush is concerned I sized a 50 amp circuit breaker but if it can?t handle the surge a higher rated device can be installed not to exceed 225% of the FLA.
 
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