30A outlet on a 30A breaker

[bunuelbresson]

Hey guys,

An equipment has a FLA of 30A, and has a L6-30P plug, and should go into an L6-30R outlet.

If a 30A breaker is installed to protect the circuit, the circuit breaker would generally be rated at 80% so would not be able to take a full 30A load. And we are not allowed to install a 40A breaker since the circuit would have a rating higher than the outlet can tolerate.

What is the solution?

Thanks

 

[infinity]

Since the factory plug is 30 amps I would assume that this isn't a continuous load therefore it can be on a 30 amp circuit. You cannot use a 30 amp receptacle on a 40 amp circuit.

 

[JFletcher]

If your load is not continuous, you can use 100% of the breakers rating.

What exactly is this equipment, and do you have the nameplate information for it? Is the 6-30 plug on it from the factory?

 

[MAC702]

...An equipment has a FLA of 30A, and has a L6-30P plug,...

It's okay to be specific with what the equipment is. Who/what determined the FLA of 30 A, and who installed the plug?

 

[bunuelbresson]

If your load is not continuous, you can use 100% of the breakers rating.

What exactly is this equipment, and do you have the nameplate information for it? Is the 6-30 plug on it from the factory?

The equipment is an IT equipment and I could not tell if it is a continuous or non-continuous load. I don't have the nameplate on me, but it says maximum load current 30.5A.

The cord and plug are factory installed and the equipment is brand new.

I believe there is no option but to go with a 30A breaker. are there in the market 100% rated 30A breakers? or is the 100% rating reserved for bigger CBs?

 

[infinity]

30 amp factory plug = 30 amp receptacle = 30 amp circuit. There's really no other way to do it unless you cut off the 30 amp plug.

 

[JFletcher]

The equipment is an IT equipment and I could not tell if it is a continuous or non-continuous load. I don't have the nameplate on me, but it says maximum load current 30.5A.

The cord and plug are factory installed and the equipment is brand new.

I believe there is no option but to go with a 30A breaker. are there in the market 100% rated 30A breakers? or is the 100% rating reserved for bigger CBs?

Wow, that is a terrible set of specs to work with.

you are not going to find a 30 amp breaker that goes in a panel board that is rated for 100%... At best it would be a 30 amp fused disconnect going to a 40 amp breaker.

I do not know if that 30.5 amp load is continuous, or rounded, or contains motor loads, and off the top of my head I do not know if you are allowed to round down to wire this with #10 conductors.

Since this is brand new equipment, I assume that you have the manual... I would read through it and see what it says.

 

[MAC702]

The equipment is an IT equipment and I could not tell if it is a continuous or non-continuous load. I don't have the nameplate on me, but it says maximum load current 30.5A.

The cord and plug are factory installed and the equipment is brand new.

I believe there is no option but to go with a 30A breaker...

I like hearing "maximum load current" instead of the "FLA" in the opening post.

Is this a UL or otherwise Listed assembly?

Regardless, the factory cord means a 30A receptacle on a 30A breaker.

 

[Chamuit]

30 amp factory plug = 30 amp receptacle = 30 amp circuit. There's really no other way to do it unless you cut off the 30 amp plug.

I worked in a Data Center for a while. Infinity is right.

 

[petersonra]

I like hearing "maximum load current" instead of the "FLA" in the opening post.

Is this a UL or otherwise Listed assembly?

Regardless, the factory cord means a 30A receptacle on a 30A breaker.

I doubt it is considered a motor or combination load thus it would not have a FLA rating. However, it does have a rated maximum current.

I don't see how it could possibly be considered a continuous load.

Continuous Load. A load where the maximum current is
expected to continue for 3 hours or more.

 

[LarryFine]

I'd say you're overthinking it and should just go with standard 30 amp everything.

 

[kwired]

Hey guys,

An equipment has a FLA of 30A, and has a L6-30P plug, and should go into an L6-30R outlet.

If a 30A breaker is installed to protect the circuit, the circuit breaker would generally be rated at 80% so would not be able to take a full 30A load. And we are not allowed to install a 40A breaker since the circuit would have a rating higher than the outlet can tolerate.

What is the solution?

Thanks

That 80% is for continuous loads. You can have 30 amps of non continuous load on a 30 amp breaker and 30 amp conductor, or a combination of 125% continuous load plus non continuous load that is no more than 30 amps.

 

[DrSparks]

Yup, just do what the engineers tell you! If the breaker burns up the panel then maybe you have a lawsuit!

 

[JFletcher]

That 80% is for continuous loads. You can have 30 amps of non continuous load on a 30 amp breaker and 30 amp conductor, or a combination of 125% continuous load plus non continuous load that is no more than 30 amps.

Yes, however he has 30.5 amps.

That said, I agree with all those that said just run it and conveniently ignore that half an amp... The only thing one could do to make it slightly more compliant is run #8 to avoid a 240.4 violation

 

[infinity]

Yes, however he has 30.5 amps.

That said, I agree with all those that said just run it and conveniently ignore that half an amp... The only thing one could do to make it slightly more compliant is run #8 to avoid a 240.4 violation

How would you have a violation if the OCPD were 30 amps and you ran #10 conductors?

 

[JFletcher]

How would you have a violation if the OCPD were 30 amps and you ran #10 conductors?

you wouldn't, but you are not supposed to put a 30.5 amp load on a 30 amp breaker or number 10 conductors.

Or am I miss remembering the rules on rounding down? 220.5 (B) only deals with calculated loads, not with manufacturer name plates.

 

[kwired]

you wouldn't, but you are not supposed to put a 30.5 amp load on a 30 amp breaker or number 10 conductors.

Or am I miss remembering the rules on rounding down? 220.5 (B) only deals with calculated loads, not with manufacturer name plates.

Many will say you don't have a safety issue as the conductor is proteted from overload, but yes you do have a code violation as you can't put a 30.5 amp load on the 30 amp conductor or the 30 amp breaker per 210.19, 210.20, 215.2 and 215.3

 

[JFletcher]

Many will say you don't have a safety issue as the conductor is proteted from overload, but yes you do have a code violation as you can't put a 30.5 amp load on the 30 amp conductor or the 30 amp breaker per 210.19, 210.20, 215.2 and 215.3

I agree with you on both points, safety and the code issues.

Since cutting off the factory plug would probably violate the listing and or the warranty, the closest one could probably get to 100% compliant install with a 30.5 amp maximum load would be to have a 6-30R wired with #8cu to a 30 amp fused disco (60A frame) going to a 35 or 40 amp breaker.

The wire is sized to carry the maximum load, the receptacle is protected at 30 amps, and if the load is continuous at 24+A, you have enough breaker to cover it. I do not work with fuses often, though I would presume that like a stand-alone breaker, they would be 100% rated. That is still fudging things a bit, and is probably never going to be implemented over just plugging in the equipment on the 6-30r to a 30 amp breaker.

 

[infinity]

I agree with you on both points, safety and the code issues.

Since cutting off the factory plug would probably violate the listing and or the warranty, the closest one could probably get to 100% compliant install with a 30.5 amp maximum load would be to have a 6-30R wired with #8cu to a 30 amp fused disco (60A frame) going to a 35 or 40 amp breaker.

The wire is sized to carry the maximum load, the receptacle is protected at 30 amps, and if the load is continuous at 24+A, you have enough breaker to cover it. I do not work with fuses often, though I would presume that like a stand-alone breaker, they would be 100% rated. That is still fudging things a bit, and is probably never going to be implemented over just plugging in the equipment on the 6-30r to a 30 amp breaker.

If you're increasing the conductor size and OCPD size because the load exceeds 30 amps how does a 30 amp receptacle make the installation code compliant?

 

[JFletcher]

If you're increasing the conductor size and OCPD size because the load exceeds 30 amps how does a 30 amp receptacle make the installation code compliant?

I said it was still fudging things a bit. like you wrote earlier, cutting off the factory plug and rewiring it start to finish *may* be the only hundred percent compliant way.

cutting off the factory plug could also violate the listing and the warranty of the equipment, correct? And if the instructions said "do not hardwire", then there is a 110.3 (b) violation.

220.5 probably does come into play since the nameplate information is a calculated and not measured load. How or if the manufacturer rounded to get to that 30.5 amps makes all the difference in the world.

Say the calculated load was 30.46 amps, and the manufacturer just rounded it to 30.5 for the nameplate. If so, then there is no problem* in using a 30 amp plug to 30 amp receptacle on 10 gauge wire to a 30 amp breaker.

if the name plate is because the equipment is calculated to draw 30.5 amps, either on the nose or rounded down from a maximum of 30.54, then you are using a calculated load that cannot be rounded down.

This is why I wrote in post #7, 'what a terrible set of specs to work with'.

*If not a continuous load, which we still do not definitively know.