Adding a New Production Line: Does Your Electrical System Have the Capacity?
Adding a production line feels like a mechanical and process decision. It's an electrical-capacity decision first. Order the machines, then discover your supply or main switchboard can't feed them, and you've turned a planned expansion into an emergency upgrade. Here's how to check capacity properly, in order.
1. Add up the real new load
Get the actual electrical demand of the new line — nameplate ratings, but more usefully the realistic running and starting demand, including motor inrush and any simultaneous peaks. This is the number everything else is checked against.
2. Check the incoming supply and transformer
Does your existing supply (and customer-substation transformer) have headroom for the new load on top of current demand? If the transformer is already near capacity, you may need an upgrade and an application to MEA or PEA — which has a lead time of weeks to months, so it must start early.
3. Check the main switchboard and the feeders
Even if the supply is fine, the question is whether the MSB has spare capacity and spare outgoing ways, and whether the relevant Sub-MSB can feed the new line. A new load can pass at the final board but overload an upstream feeder or the main — always check the whole path.
4. Re-check protection coordination
New load means new breakers, and the protection study must be revisited so faults still trip locally rather than dropping the whole plant. Adding a big breaker without re-checking discrimination is how a single machine fault takes down a factory.
5. Decide: spare capacity, or an upgrade?
One of three outcomes: you have headroom and just add circuits; you're close and need a main switchboard upgrade or additional Sub-MSB; or you need more supply capacity (transformer + utility application). Knowing which — before you order equipment — is the entire point.
6. Plan the cut-in
If an upgrade is needed on a live plant, the tie-in usually means a planned shutdown and possibly a temporary generator. Plan that window around production, not the other way round. Our contractor checklist covers how to vet a contractor for exactly this kind of live-site work.
FAQ
Frequently asked questions
Can't I just add a breaker for the new line?
Only if the MSB, the upstream feeder and the supply all have headroom, and protection still coordinates. A breaker at the board is the last check, not the first — the capacity question runs all the way back to the transformer.
How do I know if my transformer has spare capacity?
Measure actual peak demand (ideally with metering over a representative period) against the transformer rating. Nameplate-only estimates miss real peaks — monitoring gives a defensible figure.
How long does a supply upgrade take if I need one?
For an MV transformer upgrade, realistically 8–16 weeks via MEA/PEA depending on area and scope. That lead time is exactly why the capacity check must happen before you order machines.
Will adding a line require a shutdown?
Adding circuits to a board with spare ways often doesn't; a switchboard or transformer upgrade usually does. Good planning (and a temporary generator) keeps the downtime to a single controlled window.