Do electrical rooms need to be fire rated?

[Sparky5150]

Is it mandatory?
What if there is a transformer?

 

[iwire]

In general no, not by the NEC

A transformer might change things along with local codes.

In my area emergency electric rooms must be fire rated.

II. Specific Provisions Applicable to Different Types of Transformers
450.21 Dry-Type Transformers Installed Indoors.

(B) Over 1121/2 kVA. Individual dry-type transformers of more than 1121/2 kVA rating shall be installed in a transformer room of fire-resistant construction. Unless specified otherwise in this article, the term fire resistant means a construction having a minimum fire rating of 1 hour.

Exception No. 1: Transformers with Class 155 or higher insulation systems and separated from combustible material by a fire-resistant, heat-insulating barrier or by not less than 1.83 m (6 ft) horizontally and 3.7 m (12 ft) vertically.

Exception No. 2: Transformers with Class 155 or higher insulation systems and completely enclosed except for ventilating openings.

 

[bphgravity]

Review your building code for the specific occupancy type and construction type requirements, and always check the plan specifications.

 

[Sparky5150]

Exception No. 2: Transformers with Class 155 or higher insulation systems and completely enclosed except for ventilating openings.


Dont most standard dry type transformers over 112.5 meet this exception?

I think this code is highly misunderstood.

 

[iwire]

Exception No. 2: Transformers with Class 155 or higher insulation systems and completely enclosed except for ventilating openings.


Dont most standard dry type transformers over 112.5 meet this exception?

I believe so, that is why I said a transformer might change the answer.

I think this code is highly misunderstood.

A safe bet.

 

[Sparky5150]

Seriously tho, does anyone know the answer?

If you have a 150kva Sq D dry-type transformer in an electrical room, does it need to be rated?

 

[sandsnow]

Q1 It does not need to be rated just because it is an electrical room. It's another myth in the industry. Many desingers automatically rate it.

Q2 If the XFMR has Class 155 or higher insulation systems and completely enclosed except for ventilating opening; then no rating. All modern XFMRs I've seen have Class 220, so no rating required. There may be some oddball XFMRs out there.

 

[Sparky5150]

sandsnow, thanks for the confirmation!

This is one subject that building depts comment on all the time, it just gets to be a pain having to defend it constantly.