Power in an industrial bay

Electrical capacity is the service question that most often kills an otherwise good bay, and it is the one tenants are least equipped to ask about. Three numbers describe what a bay has: amperage, phase and voltage. You need all three.

Amperage

Amperage is the size of the service — how much current the bay can draw at once. Small bays commonly have 100 or 200 amps. Larger bays and light-manufacturing units have more. The number on the panel is the maximum, not what is available after existing loads.

Phase

Single-phase power runs lighting, receptacles, office equipment and small tools. Three-phase power runs most fixed industrial machinery — compressors above a certain size, larger motors, welders, CNC equipment, commercial refrigeration.

This is the one to check first. If your equipment needs three-phase and the bay has only single-phase, bringing three-phase in can mean a utility service upgrade, a transformer and a wait measured in months. In some locations it is not available at all.

Voltage

The common Canadian industrial combinations are 120/208 volts and 347/600 volts. Equipment is built for one or the other. A 600-volt building can run 208-volt equipment through a transformer, and vice versa, but that transformer is a real cost and it takes physical space on the wall.

Working out what you need

1. List every piece of equipment and find its nameplate rating — amps, volts and phase.
2. Separate what runs continuously from what runs intermittently.
3. Add the continuous loads, then add the largest intermittent load.
4. Add lighting, HVAC, office and any future equipment you can foresee.
5. Apply the demand factors an electrician will use, and leave headroom — a service running at its limit is a service you will be upgrading.
6. Have an electrician confirm the calculation before you sign anything.

The electrical load estimator does the arithmetic. It is a planning aid, not a code calculation, and it does not replace an electrician's load assessment.

What an upgrade involves

Upgrading a bay's service is rarely just a bigger panel. Depending on how far you are going, it can involve new conductors from the building's main distribution, a larger main breaker, utility coordination, a new or upgraded transformer, an electrical permit and an inspection. Where the building's main service is itself at capacity, the upgrade becomes a building-wide project and the landlord's appetite for it decides the answer.

Establish in the lease negotiation who pays for the upgrade, who owns the equipment afterwards, and what happens at the end of the term. This is a normal thing to negotiate and a bad thing to discover afterwards.

Metering

Ask whether the bay is separately metered. If it is, you contract directly with the retailer and you control the account. If it is not, your electricity arrives as part of additional rent, apportioned by a formula in the lease — which is fine if your consumption is typical and expensive if it is not. A high-draw tenant in a building that apportions power by area is subsidised by its neighbours; a low-draw tenant subsidises them.