is it safe to change to 100 amps from 60 amps without replacing your old knob and tube wirinig

4/29/2019 at 6:44:10 AM

First, knob and tube is a very old and outdated method of wiring. It consists of wires, usually uninsulated, being strung across insulators through attics and wall. This in itself is not safe.

2nd: It most likely will not have a grounding wire included in the circuitry. This makes it obsolete when used with any kind of local point of use surge protection because there is no where for the surge device to dissipate the excess energy to when it clamps down to protect the attached equipment. Assuming that there is no grounding wire I would recommend additional means of protection:

A) AFCI protection or combination Arc fault circuit breakers in the new circuit breaker box for all 120-volt, single-phase, 15-and 20-ampere branch circuits. This is now the code for all branch circuits in "dwelling units". There are a few ways to comply with this safety measure. See section 210.12 (A)(1)through(6), (B) and (C) of the National Electric Code. Also see section 210.8 about Ground-Fault Circuit-Interrupter Protection, which also must be in compliance.

B) Whole house surge protection. These devices work much the same as the type that plug into your receptacles but when there is no grounding wired in the circuit the plug in type will not work.

The whole house type act as a firewall of sorts, greatly reducing the possibility of external power surges and spikes from entering your home.

I would recommend looking into the Siemens FS 60, 100 or 140 series of whole house surge protectors. It's a rock solid product that I have on my home and that I have installed for a great many of our residential clients. Never had a complaint yet.

It should be noted that these devices will not protect against internal surges that do occur regularly in homes.

C) Arc fault protection and surge protection should be installed even in homes with properly grounded electrical systems. These 2 recommendations in no way replace the safety value of proper grounding. I would look into updating the branch circuitry in your home as well as upgrading the main service.

Answering your original question about changing to a 100 amp from a 60 amp.

Having more power available is neither more or less safe as long as the attached knob and tube wiring is protected with the correctly sized over current protection. It's how the power gets distributed throughout your home, that's where the safety issues need to be looked at.

You can visit this webpage about grounding for more information:

https://electriciansmesaaz.com/electrical-grounding-techniques-for-ungrounded-wires/

Hope this helps!