As you are fairly new to the job, I assume you haven't done much work for your customer before so you will need to explain that changing the CU will require access to the electrical installation elsewhere in the property for testing and you may have to  do work elsewhere too. You can either do the tests and sort any problems before you change the CU, as SparkieMike prefers or you can explain to your customer that once the CU is changed, testing may bring faults to light which will cost extra to sort out as Timeserved has said.

You must avoid is quoting a price to change the CU, then doing  the job and when you test finding  faults which you have to put right but didn't allow for in your quote.

I prefer to fit the CU and sort the problems after that but I only do so if my customer understands that the extra work has to be done and is chargeable.

Dave

As you are fairly new to the job, I assume you haven't done much work for your customer before so you will need to explain that changing the CU will require access to the electrical installation elsewhere in the property for testing and you may have to  do work elsewhere too. You can either do the tests and sort any problems before you change the CU, as SparkieMike prefers or you can explain to your customer that once the CU is changed, testing may bring faults to light which will cost extra to sort out as Timeserved has said.

You must avoid is quoting a price to change the CU, then doing  the job and when you test finding  faults which you have to put right but didn't allow for in your quote.

I prefer to fit the CU and sort the problems after that but I only do so if my customer understands that the extra work has to be done and is chargeable.

Dave