Lift station classified area

[JohnB1]

I've searched the previous threads, but haven't found a clear reply.
My question is is there an article in the NEC that spells out the unclassified area of a lift station? The NFPA 820 states that if you are outside 5' your in a unclassified area. The local jurisdiction says the NFPA 820 doesn't override the NEC, so the 10' rule would apply. Could this be clarified for me. Thank You

 

[oldsparky52]

The height of that classified location may be of more interest than the distance from the tank.

I assume this might have something to do with wiring methods? Equipment location?

 

[JohnB1]

It has to do with the control panel location. The wet well lid is flush with the ground. The control panel is mounted 5' from the edge of the hatch and 8' from the vent stack.

 

[rbalex]

NFPA 820 may not override the NEC; however, where did the 10' radius come from? In addition point out Section 500.4 (B), especially IN No. 1 and 2. NFPA 820 is one of the Standards cited in IN No. 2. It is quite authoratative.

 

[JohnB1]

The jurisdiction having authority is treating it as a class 1 division 1 where anything inside the 10' will be ridgid with seal offs, like you do at a gas station.

 

[oldsparky52]

The jurisdiction having authority is treating it as a class 1 division 1 where anything inside the 10' will be ridgid with seal offs, like you do at a gas station.

I'm not sure it's a C1 D1.

Anyway, the way I believe it's supposed to work, the cables that go to the float switches and motors are designed to be rated for the class and division of that tank. The cables are also long enough that you can route them above the classified area and then you are back to non classified wiring methods.

Since the cables are also rated to not pass gases and are sealed at the motor/float, an additional seal is not required if it is extended to outside of the classified location.

What I've done it the past is to extend the 2" conduit from the tank opening to just above the concrete (install a bell end) and make sure it is below the classified location upper boundary. The conduit never leaves the classified location therefore does not need seals (although I always seal the top of the conduit with ductseal after the cables are installed).

Route the cables into your enclosure through the free air (which is above the classified location).

I cannot give you code references others may. I know this has passed for me in the past.

I did see some guy once put a PVC JB on the inside of the tank and make wire nut joints in there between the (cutoff) cable and THWN wire going to the controller. That was a mess.

 

[rbalex]

The jurisdiction having authority is treating it as a class 1 division 1 where anything inside the 10' will be ridgid with seal offs, like you do at a gas station.

Then the AHJ needs to read and reread the Scope of Article 514 until they recognize it doesn't apply to CNG facilities; however, NFPA 820 does apply.

 

[JohnB1]

The AHJ is referring to article 501 35

 

[augie47]

The AHJ is referring to article 501 35

??

 

[oldsparky52]

501.140(A)(3)

 

[rbalex]

501.140(A)(3)

That may apply to, "How to install something", but how does it apply to the classification radius that the OP originally asked about?

 

[rbalex]

??

:thumbsup:

 

[JohnB1]

The question is not about cords. It's where are seal offs required to be. I'm being told a seal off is required on the service with it being located 6' 6" from the wet well hatch and 8'6" from the vent. I have seal offs from the wet well to the control panel that is located 5' to the face off the panel from the wet well hatch.

 

[oldsparky52]

The question is not about cords. It's where are seal offs required to be. I'm being told a seal off is required on the service with it being located 6' 6" from the wet well hatch and 8'6" from the vent. I have seal offs from the wet well to the control panel that is located 5' to the face off the panel from the wet well hatch.

If the feeder conduit has a fitting in the classified location then yes, it will need a sealoff.

IMO, you are making a mistake to have sealoffs in the conduit from the wet well. If you don't let that conduit leave the classified location then why does it need to be sealed? If the cables in that conduit are allowed in a classified location why does that conduit need to be sealed?

You should not have to break sealoffs in order to change out one of the motors or float switches. You better not have a junction box in that well. IMO, the AHJ is mistaken on this.

 

[oldsparky52]

That may apply to, "How to install something", but how does it apply to the classification radius that the OP originally asked about?

It doesn't. I just hate to see someone install sealoffs on those cords.

 

[Petemoran]

Lift station

Lift station

Here in south MS i am over about 126 liftstations in my city , the way our stations are done is we have a J-box mounted on top of our wet well with holes board threw the concrete top plate of wet well our motor and float leads are pulled into this box and made up to our thhn wires from the panel .. The conduit that carries these wires from the control panel to the j-box have sealoffs installed on them to keep gases out of the panel .. connections in the j-box are made with weather proof wire nuts and split bolts .. A lot of people say there needs to be a seal off as soon as the pipe leaves the wet well but this means each time the u change a float you would have to bet the sealant out of the seal off and prob damage your wires ... The way we have been doing it has been working well ...

 

[augie47]

Here in south MS i am over about 126 liftstations in my city , the way our stations are done is we have a J-box mounted on top of our wet well with holes board threw the concrete top plate of wet well our motor and float leads are pulled into this box and made up to our thhn wires from the panel .. The conduit that carries these wires from the control panel to the j-box have sealoffs installed on them to keep gases out of the panel .. connections in the j-box are made with weather proof wire nuts and split bolts .. A lot of people say there needs to be a seal off as soon as the pipe leaves the wet well but this means each time the u change a float you would have to bet the sealant out of the seal off and prob damage your wires ... The way we have been doing it has been working well ...

\

All I can say is that under the right conditions, those words may be engraved in a tombstone

 

[Petemoran]

Can u alabarate it is being told to us by the inspector this is acceptable !!

 

[Petemoran]

Can u alabarate it is being told to us by the inspector this is acceptable !!

The motor leads come in threw the bottom of the j-box..

 

[augie47]

There are folks here far more qualified to answer so I'll await their input but it sounds to me like you have splices in a Classified location... no classified box, no seal-offs