What Kind Of Cable Was This?

[infinity]

he must not be the only one because if you look in the old 2017 code handbook its the example in exhibit 725.3 :
Typical installation of an automatic oil burner unit for a boiler employing a safety shutdown circuit required to be Class 1.
View attachment 2578953

Nice graphic. I never thought of the toggle switch ahead of the actual safety control devices to be part of the Class 1 portion of the circuit. Following this graphic is does make sense that they may be part of the safety requirement.

 

[Joethemechanic]

I'm just thinking. Where exactly does this emergency switch have to be? One of my stoker boilers is an EFM DF520. DF is for dual fuel. It's all set up to run on coal or oil but I just never got around to installing the oil burner gun. If I do install it should the switch just be outside the boiler room, or in my downstairs office? I kind of think I should install a second switch because there is also a door between the boiler room and the shop.

Actually I have a burner gun here that can burn oil, or propane, that is probably the one I'm going to put in although I don't have any propane storage here. at least not yet

 

[hbiss]

AFAIK there is nothing that says you can't have more than one. If the boiler is in the basement, there needs to be one at the top of the stairs from the first floor. I like to put another outside the boiler room door. All should be at about 5' AFF with a red plate that says "Oil Burner Emergency Switch". You use a toggle even though the rest of the house may be Decora.

-Hal

 

[JohnE]

Nice graphic. I never thought of the toggle switch ahead of the actual safety control devices to be part of the Class 1 portion of the circuit. Following this graphic is does make sense that they may be part of the safety requirement.

I don't think the toggle switch would be part of the class 1 portion of the circuit. I've never heard anyone interpreting it this way, and I've been in thousands of houses in MA. Built and wired in every decade. I've never seen or heard any inspector interpreting it that way. That doesn't mean anything really. My thinking is aligned with everything else you posted in this thread. I don't think that graphic is indicating the "emergency switch" of the branch circuit.

 

[infinity]

I don't think the toggle switch would be part of the class 1 portion of the circuit. I've never heard anyone interpreting it this way, and I've been in thousands of houses in MA. Built and wired in every decade. I've never seen or heard any inspector interpreting it that way.

I don't think so either but the response from the inspector in post #74 seems to imply otherwise. The graphic in post #80 shows the Class 1 portion of the circuit after the thermal safety control not before which IMO is part of the branch circuit.

 

[kwired]

Nice graphic. I never thought of the toggle switch ahead of the actual safety control devices to be part of the Class 1 portion of the circuit. Following this graphic is does make sense that they may be part of the safety requirement.

Keep in mind the image was from NEC handbook and is not an official NFPA interpretation of what the NEC content means.
Is this a part of "safety control equipment"?
Doesn't that typically mean there is a "safety relay" on some machine or even group of machines that may have open components with possible injury should a person get too close to any hazards? Some the activating devices might even be proximity sensors? Simple limit switch on some guard that directly connects to the machine controls isn't necessarily considered to be a part of this. If it ties to a "safety relay" instead of the main machine controls then it probably is a part of safety control equipment.

 

[JohnE]

I don't think so either but the response from the inspector in post #74 seems to imply otherwise.

I think the inspector's reply contains some of his personal interpretation. I'll have to review NFPA 31.....

 

[WD40]

I don't think the toggle switch would be part of the class 1 portion of the circuit. I've never heard anyone interpreting it this way, and I've been in thousands of houses in MA. Built and wired in every decade. I've never seen or heard any inspector interpreting it that way. That doesn't mean anything really. My thinking is aligned with everything else you posted in this thread. I don't think that graphic is indicating the "emergency switch" of the branch circuit.

If the switch was not part of the class 1 safety system the cover would not be required to say "Oil Burner Emergency Switch". It has always been a class 1 circuit run with MC, I have seen it 1000's of times in MC or BX since I started in the trade.
You can run romex from the breaker to the switch (if romex is otherwise allowed)
The HVAC people probably don't know because nobody installs oil heat anymore. But if you service them you should know. And its only Oil heat not gas.
I can't remember the last time I installed a oil burner do people still install these in new homes in MA?

 

[Eddie702]

I don't think the toggle switch would be part of the class 1 portion of the circuit. I've never heard anyone interpreting it this way, and I've been in thousands of houses in MA. Built and wired in every decade. I've never seen or heard any inspector interpreting it that way. That doesn't mean anything really. My thinking is aligned with everything else you posted in this thread. I don't think that graphic is indicating the "emergency switch" of the branch circuit.

Then 99% of the oil burners in MA must be illegal. I have been an oil tech in MA licensed for 52 years and electrical licensed for 44 years and they are (emergency switches) are all done in NM except the really old jobs done before NM was popular.

The requirement for more than two switches at multiple boiler room entrances is an ASME boiler code thing and applies to oil & gas burners over 200000btu commercial that is part of the CSD-1 ASME boiler controls. This has only been starting to be enforced in the last 10-15 years or so

 

[WD40]

Then 99% of the oil burners in MA must be illegal.

Just because some area (or one company) ignored the code for decades does not make it legal, I see HVAC NEC violations all the time.
Its a 'emergency switch' with a required red cover stating that its an emergency switch, how could that not be part of the safety system required by the NFPA oil burner code?

Looked it up in my code book (2017) and it could be that some AHJ may accept romex it says "or otherwise suitably protected" after the wiring methods.
Regardless of the wiring method the class 1 safety circuit begins at the 'emergency' switch any oil burner tech should know that.

 

[Eddie702]

Just because some area (or one company) ignored the code for decades does not make it legal, I see HVAC NEC violations all the time.
Its a 'emergency switch' with a required red cover stating that its an emergency switch, how could that not be part of the safety system required by the NFPA oil burner code?

Looked it up in my code book (2017) and it could be that some AHJ may accept romex it says "or otherwise suitably protected" after the wiring methods.
Regardless of the wiring method the class 1 safety circuit begins at the 'emergency' switch any oil burner tech should know that.

Makes absolutely no sense to me. So the circuit from the panel to the ES can be NM but the circuit from the ES to the burner must be in pipe, AC, MC etc?. I don't think that is the intention.

Yet gas burners furnaces and boilers need no switch at all. Most ESs are wired with the power brought to a J box at the boiler and they are wired as a switch loop

 

[Eddie702]

This is from NFPA 31:10.5.1.2

For electrically powered appliances, the requirement of 10.5.1 shall be accomplished by an identified switch in the burner supply circuit, placed outside of and adjacent to the entrance to the room where the appliance is located.

And this:

4.4 Electrical Services. 4.4.1 Electrical wiring and utilization equipment used in connection with oil-burning appliances or equipment shall be installed in accordance with NFPA70, National Electrical Code. {2761385F-AD14-4E8D-90C4-0509A0D2E7D7} 4.4.2 Safety control circuits shall be 2-wire, one side grounded, with a nominal voltage not exceeding 150 volts. 4.4.3 Safety controls or protective devices shall be connected so that they interrupt the ungrounded conductor and shut all fuel flow to the appliance, including fuel flow to any pilot flame or burner. 4.4.4 The control circuit shall be connected to a power supply branch circuit fused at not more than the value appropriate for the rating of any control or device included in the circuit.

 

[Eddie702]

Doesn't 724.40 limit class 1 to 30 volts and 1000va?

 

[WD40]

Doesn't 724.40 limit class 1 to 30 volts and 1000va?

Your thinking class 2, A class 1 circuit is almost the same as a branch circuit but you can use 18 AWG @ 7A and 16 AWG @ 10A, you use a chapter 3 wiring method.
Having re-read the code sections it seems the safety circuit does starts at the emergency switch, but the code does not prohibit romex explicitly, if suitably protected.
It is an AHJ call if its suitably protected.

And since were off topic I am still interested if anyone installs oil boilers in new homes ?
I know oil has more btu's than LP per gallon but I thought they are much less efficient?

 

[Eddie702]

@WD40
I have been out of the oil thing for a while so I don't know how many are being installed in new homes. But the trend in new homes is heat pumps and "all electric" even if it is more expensive to operate. Some cities/towns in MA (and other areas) are putting the stop on new Natural Gas homes. As far as rural areas propane is more efficient than oil IF you use a condensing boiler but propane is much more expensive than oil/btu. Oil usually come out much cheaper unless the building has low temp radiant heat.

The combustion efficiency on oil is about 84ish%. Propane is 95ish % if ysing low temp radiant but with standard baseboard its about the same as oil.

Oil has about 138-140,000 btu/gallon and propane is around 95,000btu/gallon so the gallons are not = for comparison you have to compare price/BTU

 

[pipe_bender]

But the trend in new homes is heat pumps and "all electric" even if it is more expensive to operate.

Have you seen the heat pump air to water 'boilers'? I just wired one up for a HVAC company, my first one its interesting;

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The company is out of Westfield I guess.

 

[hbiss]

Makes absolutely no sense to me. So the circuit from the panel to the ES can be NM but the circuit from the ES to the burner must be in pipe, AC, MC etc?. I don't think that is the intention.

Looking at that graphic again, I agree that you are correct. If a fire disrupted the wiring as drawn, it would only result in a boiler shut down. I don't think I have ever seen a boiler wired that way other than the service switch on the side of the boiler- hot and neutral from the panel up to the emergency switch then back down to the boiler. What I am used to is the emergency switch(s) on their own switch leg off the circuit as shown. If a fire were to damage the switch leg it would short the switch leg and render the switch useless. I can see the switch leg being a Class 1 circuit, but only the switch and switch leg.

Some cities/towns in MA (and other areas) are putting the stop on new Natural Gas homes.

Not anymore.

-Hal

 

[JohnE]

I'm in new houses, as an inspector and as a contractor, every day here in MA. I haven't seen an oil burner in new construction in over 10 years. If there isn't city gas, I see propane or heat pumps.