If it is roof drains you are talking about, this calculator may help you: http://www.portalsplus.com/drain_calc.htm
250 mcm
A 200 amp service panel with a 60 amp sub-panel.
For a service rated at 400 amps using 500 MCM THHN copper conductors, the minimum size for a copper grounding electrode conductor (GEC) can be determined using the National Electrical Code (NEC) guidelines. According to NEC Table 250.66, for a service of 400 amps, the minimum size for a copper GEC is 4 AWG. However, if the GEC is connected to a ground rod, it must be a minimum of 6 AWG copper.
250 MCM aluminum minimum
A 100 amp residential service requires a size #8 copper wire, it should be insulated in green.
250 mcm
Please be more specific about 'service'.
50 amps
24".
50 amps
A 200 amp service panel with a 60 amp sub-panel.
The wire that is used for connecting the ground rod or plate to the electrical distribution is governed by the size of the electriclal distribution. In Canada a #6 bare copper is the minimum size for a 200 amp service.
Supported minimum size
250 MCM aluminum minimum
For a 200 amp service, a minimum of 2/0 gauge aluminum wire should be used.
It depends on the replication plant. Most facilities require a 1000pc minimum and a few will take 500pc orders. It differs from service provider to service provider. Few keep it to as low as one, while others require a minimum quantity to offer the service at a better rate. You need to get in touch with concerned people to get an exact idea.
A #1 copper conductor with an insulation rating of 90 degrees C is rated at 145 amps.