NEC Battery Container for explosive atmospheres

[Schaller]

Hi all,
I’m looking for applicable standards that a battery container for a UPS must meet for NEC approval in explosive atmospheres.
I have done the same for the standard IEC 60079-7 before but I just can’t find any appropriate standards for NEC, except:

• NFPA 70,2017 -> Only battery storage in general and not in conjunction with Ex-atmospheres
• UL 1778 Uninterruptible Power Systems, same problem as before

I'm sorry for the probably stupid question, but I'm working with such standards for the first time after my studies and thought that there would be a similar standard as the IEC 60079-7, which describes e.g.:

• The handling of batteries in various protection areas in detail
• The dimensions of the vents with formulas for calculation.
• …

I would be very happy if someone could help me with my problem.

Best regards,
Manuel

 

[rbalex]

Your problem is attempting to apply IEC Standards to US domestic installations. The IEC-60079 series has a far greater scope that the US NEC alone, which is primarily (although not exclusively) an installation standard. Other references to battery applications be found in IEEE standards, such as Stds - 484, 485, 1184, 1187, 1188, 1189, and 1375. This is not an exhaustive list, but I don't intend to do you homework for you. Other NEC standards and Standard organizations, such as FM, also speak to various application issues you may be interested in. INTERTEK has broad experience with US standards as well and may be able to help you.

That said, many of the IEC rules are philosophically compatible (the laws of physics and chemistry are still the same worldwide)

 

[IntrinsicSafety]

As far as I am aware, there is no rule that says you can stick batteries in a "compliant" box and be allowed into the hazloc. Rather, the entire battery box unit will have to be certified to an equipment standard.

IEC 60079-7 is an equipment standard, implying that previously, you certified the entire battery box type 'eb' for Zone 1. The situation will be the same for North America, but with North American standards:

- For Division 2, you will be looking at ISA 12.12.01. (You could alternatively use UL 60079-7 and certify as type 'eb' or 'ec', though 'ec' is not yet in the NEC.)

- For Division 1, you will need to comply with intrinsic safety per UL 913. UL 913 requires you comply with UL 60079-0 and UL 60079-11 for type 'ia' equipment.

There is also the potential issue that lead-acid UPS batteries may vent hydrogen into the box itself, making the interior of the box a Div 1 location rather than a Div 2 location. This would only normally be a small amount but can build up over time; often it can be fixed with venting. Some guidance on this can be found in the Note of API RP500 8.2.6.7.

If you want to use ISA 12.12.01 or UL 913, but there is good applications information in a UL/IEC 60079 standard, most agencies will let you use it under the "best available guidance" principle. That is, however, a matter of interpretation for your agency.

 

[Schaller]

As far as I am aware, there is no rule that says you can stick batteries in a "compliant" box and be allowed into the hazloc. Rather, the entire battery box unit will have to be certified to an equipment standard.

IEC 60079-7 is an equipment standard, implying that previously, you certified the entire battery box type 'eb' for Zone 1. The situation will be the same for North America, but with North American standards:

- For Division 2, you will be looking at ISA 12.12.01. (You could alternatively use UL 60079-7 and certify as type 'eb' or 'ec', though 'ec' is not yet in the NEC.)

- For Division 1, you will need to comply with intrinsic safety per UL 913. UL 913 requires you comply with UL 60079-0 and UL 60079-11 for type 'ia' equipment.

There is also the potential issue that lead-acid UPS batteries may vent hydrogen into the box itself, making the interior of the box a Div 1 location rather than a Div 2 location. This would only normally be a small amount but can build up over time; often it can be fixed with venting. Some guidance on this can be found in the Note of API RP500 8.2.6.7.

If you want to use ISA 12.12.01 or UL 913, but there is good applications information in a UL/IEC 60079 standard, most agencies will let you use it under the "best available guidance" principle. That is, however, a matter of interpretation for your agency.

Thanks a lot, that's what I was looking for.


Department 1 is unimportant to me, as it does not have its own application.