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thanks for the response, there hasn't been many. THe NFPA states that the mere presence of a flammable does not necessitate a hazardous rating. I am well acquinted with the NFPA articles, but they don't answer my question. As stated, 1ml of acetone in a test tube would not necessitate a haz...

So NFPA says that the mere presence of a flammable does not necessitate a hazardous area classification. So no one would question the lab chemist pouring acetone from a one liter beaker into a test tube on a lab bench, insisting that necessitates a hazardous area classification. At least I...

Do you really believe that utilities in the US use 20 years as a threshold to replace high voltage distribution equipment? Would you have suggested that to GE when they were designing their Magnablast line of switchgear? Even if it needs to be replaced a customer should be able to converse...

You would think!!!! But times have changed. When you call headquarters looking for help, they direct you to the area sales rep. they tell you specifically that we don't accept calls from customers. The sales rep is selling their products and 20 other manufacturers. So its a came of...

Got a G&W SF6 4-way switchgear 25KV. Think a CT inside the tank went bad. Unit is 20 years old but in excellent condition. Do you know of any shop that is doing quality repair of SF6 gear. I'm on the East Coast but could ship it anywhere in US. Any leads appreciated.

Found this in an ECM reference: Though TEFC motors typically don’t have a T-Code stamped on the nameplate with the maximum surface temperature, internal and external temperatures of the motor must be considered. IEEE Std. 841, IEEE Standard for Petroleum and Chemical Industry —...

I'm in the 2020 NEC and 501.125(B) is for Class I, Division 2. Sub (3) is the reference to 'open' or 'non explosionproof' motors. There is no mention about surface temp, only non arcing components. Sub (4) refers to surface temp, but only when space heaters are installed. In the blue...

TEFC motors in a Class 1 Division 2 locations is permitted per NEC providing no arcing contacts NEC 501.125B4. But TEFC motors don't normally come with T codes on the label. If a Div2 area is say T3, can you use a generic TEFC motor without thermostats (without surface heaters or arcing...

Showing my age, but, years ago motor manufacturers would make Class 1 EX motors, and Class 1 and 2 EX motors. Motors that were exclusively Class 1 often didn't have internal thermostats and would have a T code of T2B (or T2C). Today, most manufacturers are limiting inventory and only selling...

this haa been an excellent response. Special thanks to GR8blu for explaining this in a way that even I can understand.

Would you have any input on why the T rating for gases would be so low. I fully understand why it is that low for dust which have much lower auto ignition temperatures, but gases have much higher auto ignition temperatures, typically in the 400C range. Is it just to cover those very few...

Few questions regards Hazardous area classification. I understand the need for T code limits in Class II area as dust have a much lower auto ignition temperature than gases. But how are T codes assigned to Class I in Groups A,B,C,D. I know you would look up the auto ignition temperatures of...

On a solidly grounded wye medium voltage distribution, say switchgear to switchgear, using 100 percent foil shielded 105C EPR cable, is is required to run an Equipment Grounded Conductor. If it is, can the EGC be bare or 600V insulated. There is a CT per phase conductor and zero sequence CT.

250.194 ... a substation with exposed electrical conductors and equipment. I'm really confused with regards to whether or not it is necessary to ground the metalic fence around deadfront switchgear. In an industrial setting (not utility) where you have an outdoor substation, say with medium...

I have a series string of 92 each Alcad MC14P NiCad batteries. Need to set up the charger and have some questions. Alcad recommends 1.40V/c for these batteries but doesn't provide an Equalization voltage or duration, any recommendations? Also, what would you set for Low Voltage warning, and...

Yes, this is in USA. The transformer belongs to us, not the utility. We take power off the pole as a primary metered customer to 15KV switchgear and then distribute to our building transformers that are 12.4KV-480/277. This xfrm is 2000KVA. This setup is new to me. I'm thinking there...

Need some help with Siemens RLE Low voltage switchgear trip programmer. Feed to the gear is via a 12.4KV - 480/277 2000KVA Xfrm. Three phase conductors and 50% neutral are carried to the switchgear. The switchgear has a neutral bus to land the neutral conductors. This bus also has a 2000:5...

Some are asking for the particulars so here they are: Transformer: 12.4KV-480/277, 2000 KVA, Imp 5.5% This is primary metered, we own the transformer (not the utility). Manufacturing, 24hrs/day 365 days per year, with a one week shutdown per year for maintenance. From utility bill: KW=1000KW...

Need to add 200KVAR of capacitors to my 2000KVA 12.4KV-480/277 Padmount transformer. Trying to add small KVAR units to each individual motor just isn't practical as MCC space is almost non-existent, and motors are all small, like 30hp. Thinking the easiest, cheapest approach is to add two...

The Moon paper is my primary reference. But its a bit vague on my questions. For instance, phase to ground. If you have a wye system, do you use the phase to phase voltage, or the phase to ground voltage? Thanks for explaining the 3 multiplier, the Moon paper didn't quite detail that it was...