Questions You Should Know about switchgear manufacturer

The manufacturer can send you two sections that are to be installed side-by-side and connected to each other internal to the switchgear, each being rated at amps. But you can't supply more than amps to the combination. So it depends on how you intend to install the switchgear. Will you have two or more sections, or just one?

By the way, what "120% rule" are you referring to?
Hi Charlie,

In this particular case, I am putting three separate, small PV systems all on one commercial rooftop. Each system will interconnect into the main panel of the respective office it supplies with power. Each office has a panel filled with branch breakers and is protected by a 150A OCPD located at the top of the panel.

However, these 150amp panels are supplied by a switchgear that is in an adjacent building within the office park. The switchgear seems to be comprised of (3) adjacent sections. Each section has (6) 150 amp switches that feed the aforementioned electrical panels, for a total of 18 electrical panels being supplied by the switchgear. The whole switchgear has a A load break switch. [the switchgear is a Square D Power Style Commercial Multi Metering, 208Y connection]

I'm trying to apply the 120% Rule for backfeeding the busbar throughout the whole system stream.

I'm guessing at the Switchgear sectional level, it would look something like this:

amps (max. section rating) * 120% = amps
amps - (150 amps * 6 [# of breakers on the section]) = 540 amps
Therefore I can backfeed up to 540 amps on this switchgear section

Is my thinking correct? Please let me know if I can clarify anything. Sometimes it's hard to convey what's in my head into words.

Andy

If the A buses are protected by a A switch then you're not getting very far by invoking the 120% rule. :happysad:

The NEC has this 705.12(D)(2)(3)(d):

Hmmm... this my first time designing a small commercial system where there are multiple busbars of differing ampacities involved. In the past, I've been lucky enough to easily land in a simple MDP. While I've had load calculations performed by hired electricians, I've never had fault studies done --how does one find this kind of service? Also, does "designed under supervised engineering" essentially mean that I'd have to have an electrical PE sign-off on this?

Regards,
Andy

If you replace or upgrade your switchgear, you will have to look down for various aspects such as accessibility, footprint, budget, etc. Here are five questions that you need to ask yourself before replacing or upgrading your switchgear equipment with the latest models like the arc flash switchgear.

You can find more information on our web, so please take a look.

1. What is the Reason Behind This Replacement or Upgradation?

You need to know the reason behind your replacement or upgrade of switchgear. This will help you make further decisions for the process. Some of the reasons that you can consider for your replacement or upgrade are as follows:

• Look for the availability and cost of spare parts for your switchgear. At times, the cost of spare parts for existing switchgear can be higher than the replacement cost.
• Whether you want to use arc flash swaitchgear, reduce the overall PPE with remote operations, or add more protective functions, you will need to change or replace your existing one.

2. Do I Have Enough Electrical Or Production Capacity?

If you want to add more electrical capacity, you may think about adding more circuit breakers, more transformers, and space.

• Firstly, check for the availability of the spare capacity in your transformer.
• You can increase MV feeders by two times with a stacked design to easily fit medium voltage switchgear.
• You can also increase the electrical capacity through other options like the replacement of rear and front switchgear.

3. Is There Any Accessibility Or Footprint Limitation?

You must check for the dimensions of your electrical room doors to plan the route. Then, check if there are any obstacles while replacing the switchgear or not. This will help you know the shipping splits you will need from the custom switchgear manufacturer. You can relocate some other equipment to make the best space and location for your new switchgear.

Beike Product Page

4. Can I Use My Existing Conduits for the Replacement or Upgradation?

The answer to this question depends on the various factors like:

• Location of the conduits
• Area of the cable entry
• Condition of the cables to carry the load

You can perform rerouting or splicing on a few cables to minimize your downtime and save money.

5. Do I Have Enough Budget For The Replacement Or Upgradation?

You have to ensure whether you have the budget to replace all parts of your switchgear or not. This is because both replacement and upgrade involve a considerable amount of expenses. So, know your budget before any decision.

Hopefully, these questions will help you walk you through the entire process.