What to tell my electrician

200 amp panel board for a hot tub? WOW! Usually this size panel board can run an entire house.

1. Make sure the 200a PB is fed properly. Minimum #3/0 feeders and neutral. And, most importantly, a MINIMUM of #4 ground back to source where this sub panel is fed.
If, in fact this is a sub panel... I'm guessing it is, the ground and neutral must be isolated from each other. And tell your electrician to check your main bonding and main ground at your source... make sure they are properly installed and have little resistance to ground. If the electrician seems confused... get a different electrician.

2. Most likely, the install will be with #12 romex. If the panel is more than 100' away use #10 for voltage drop. The boxes in residential are usually plastic or fiberglass attached to wood studs. If you are dealing with wood studs and non-metallic boxes... you have no need for isolated grounding.

3. If you are using fluorescent bulbs in your home, do not feed them from this panel! If possible, throw them all in the trash.

4. Isolation transformers are an extreme measure, especially since you already have some isolation with a sub panel. Transformers buzz and vibrate... eventually.

5. You can attach a surge suppressor to the panel.

6. Good quality hospital grade receptacles are adequate. Your electrician can get these for you.

7. Multiple paths to ground are BAD! Make sure the electrician understands this theory. Get the project inspected by the local authorities... talk to the inspector while onsite. Ask the inspector to check grounding. Grounding is the most important item in electrical... along with everything thing else...;)

I am a licenced electrician with 27 years experience, 5 years apprentiship.
I have been Supervision for the last 20... I have overseen Major projects such as Hospitals, Waste Treatment, Manufacturing and now Coal Burning Power House Installations. But, I started in residential.

Most importatantly... a practicing audiophile.

Best of luck with your project,
Greg

thanks for all the posts and guidance. much appreciated.

Excellent ideas, all of the above.

One addition is to ensure your circuits which feed any computer equipment are also served by armored cable (BX). The noise emitted by NM (Romex) with computers attached is terrible.

The idea of using #10 BX is a good one, but limit the circuit breaker to the rating of the receptacle (20A).

Isolation transformers serve best when connected phase-to-phase on the primary side (240V) avoiding the polluted neutral connection filled with harmonics. The secondary should be center tapped, for your equipment.

This creates a separately derived system; one which must be grounded as well. However, this ground, while connected to all available grounding electrodes (typically cold water on the street side of the main water shutoff, within two feet of the entry of the water pipe to the house) and a supplemental grounding electrode (ground rod), will be an independent connection for the derived neutral on the isolated system. This method means least electrical noise intrusion into the isolated system. BUT, it also means providing a distribution system with overcurrent protection for the derived circuits. In other words, use the transformers to feed a circuit breaker subpanel.

If your electrician doesn't immediately understand exactly what I've written above, run away fast and find a new one.

Best of luck,

Stuart Polansky
Maryland State ME #7461