Oil Containment for Electrical Transformers

M

Maravilla24

Member
Location
Maryland
Occupation
Electrical Designer
All,

I need to know where I can find information on Oil Containment for an electrical room that'll have 3 - 2000KVA and 1 - 1500KVA Medium voltage oil filled transformers. I didn't find anything on the NEC.

Anyone knows what the requirements are?
 
Maravilla24 said:
All,

I need to know where I can find information on Oil Containment for an electrical room that'll have 3 - 2000KVA and 1 - 1500KVA Medium voltage oil filled transformers. I didn't find anything on the NEC.

Anyone knows what the requirements are?
Click to expand...
Check your building and fire codes as well as the insurer.
Factory Mutual used to a good source and was acceptable to many insurers
 
Standard mineral oil transformers would have to be in a fire-rated vault. High fire point oil filled units could probably be installed indoors, but as mentioned check fire codes and local fire marshall.

As far as oil containment, my experience was that this was driven by EPA requirements and maybe local codes. EPA did not really require oil containment but the owner was responsible for any clean up required by an oil spill including any spillage into the earth. We generally installed curbs around the transformer with enough volume to contain all the oil (in one transformer) and installed basically a septic tank with an oil/water separator. The tank fills up with water, but any oil entering the tank will force out the water, leaving the oil in the tank. That's the theory at least.
 
450.23 Less-Flammable Liquid-Insulated Transformers.
Transformers insulated with listed less-flammable liquids that have a fire point of not less than 300°C shall be permitted to be installed in accordance with 450.23(A) or 450.23(B).

450.23(A) Indoor Installations.
Indoor installations shall be permitted in accordance with one of the following:
(1) In Type I or Type II buildings, in areas where all of the following requirements are met:
a. The transformer is rated 35,000 volts or less.
b. No combustible materials are stored.
c. A liquid confinement area is provided.
d. The installation complies with all the restrictions provided for in the listing of the liquid.
Informational Note: Such restrictions can include, but are not limited to, maximum pressure of the tank, use of a pressure relief valve, appropriate fuse types, and proper sizing of overcurrent protection
(2) If an automatic fire extinguishing system and a liquid confinement area is present, provided the transformer is rated 35,000 volts or less
(3) If the installation complies with 450.26
 
FM Data Sheet 5-4 Transformers (2012) has the following requirements on outdoor xfmr spill containment (I don't have a more recent version):

2.3.1.4 Spill Containment and Emergency Drainage
Spill containment requirements for environmental protection and related regulations are outside the scope
of this data sheet.
2.3.1.4.1 Provide outdoor liquid-filled transformers with spill containment when accidental release of the
transformer fluid could expose a main building or adjacent equipment or storage.
2.3.1.4.2 Design the spill containment system in accordance with Chapter 7 of IEEE STD 980-1994 (Guide
for Containment and Control of Oil Spills in Substations, 1995) or equivalent standard.
2.3.1.4.3 Where water spray protection is provided for a transformer, install additional containment or direct
the discharged water to an impoundment with a capacity of at least a 60-minute discharge of fire hoses plus
the design flow of the water spray system. Size the drainage and containment assuming adjacent water spray
systems on both sides of an exposing transformer will operate simultaneously with the original activating
system. Design drainage in accordance with DS 7-83, Drainage Systems for Flammable Liquids.
2.3.1.4.4 Provide a system for removal of rainwater from the containment area.
2.3.1.4.5 Extend the containment perimeter at least 5 ft (1.5 m) beyond fluid-containing components, including
any external coolers, for transformers with up to 1,000 gal (3.8 m3); and 8 ft (2.4 m) for transformers with
more than 1,000 gal (3.8 m3).
2.3.1.4.6 Provide containment systems for roof-mounted liquid-filled transformers as follows:
A. For transformers with 500 gal (1.9 m3) or less of insulating liquid, the containment system may be a
welded steel pan or curbed and sealed concrete pad with capacity large enough to handle the liquid in the
largest transformer.
B. For mineral oil-insulated transformers with more than 500 gal (1.9 m3), provide a rock-filled containment
design with drainage to a suitable impoundment area.
C. Open containment is acceptable for FM Approved transformer liquids.
 
jim dungar said:
But the OP was about indoor containment.
Click to expand...
totally glossed over the "electrical room". sorry about that...
for xfmrs in electrical rooms, the following requirements are provided:

2.2.1.5 Provide liquid spill containment in transformer rooms containing FM Approved and non-Approved
transformer liquids as follows:
A. Use blank liquid-tight walls sealed to the floor.
B. If interior openings must be made in these walls, locate above the level of minimum curb height specified
in item C below.
C. Design curb height or pit depth for largest design spill (based on contents of one transformer) plus 2 in.
(50 mm), but no less than 4 in. (100 mm) total height.
D. Provide individual containment for the contents of each transformer containing non-Approved liquid to
prevent spills from flowing to other transformers or important equipment in the room.
 
jtinge said:
totally glossed over the "electrical room". sorry about that...
for xfmrs in electrical rooms, the following requirements are provided:

2.2.1.5 Provide liquid spill containment in transformer rooms containing FM Approved and non-Approved
transformer liquids as follows:
A. Use blank liquid-tight walls sealed to the floor.
B. If interior openings must be made in these walls, locate above the level of minimum curb height specified
in item C below.
C. Design curb height or pit depth for largest design spill (based on contents of one transformer) plus 2 in.
(50 mm), but no less than 4 in. (100 mm) total height.
D. Provide individual containment for the contents of each transformer containing non-Approved liquid to
prevent spills from flowing to other transformers or important equipment in the room.
Click to expand...
This is good stuff if the insurer requires compliance with FM. If they don't then just provide containment because the NEC requires it as a code.
 
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