An old house built pre-50s has cloth-wrap wiring. I cannot find the amps or maker anyplace on any panel or breaker. There are five panels in the house: one main and 4 sub. There is also a low volt system. Is any of this still up to code and where can I find info on this type system?
Electrical – MO 4 4post breaker in a home running both 110 and 220 off same breaker
electrical
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National Electrical Code 2014
Article 250 Grounding and Bonding
II. System Grounding
250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).(1) General. The grounding electrode conductor connection shall be made at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
This means that the grounded (neutral) from the service must be connected to ground, and that the connection can be made by bonding the neutral bus bar to the grounding electrode.
(5) Load-Side Grounding Connections. A grounded conductor shall not be connected to normally non–current carrying metal parts of equipment, to equipment grounding conductor(s), or be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article.
This means that the grounded (neutral) conductors should only be grounded at the main service disconnnect.
If the main service panel happens to be the same place that the grounded (neutral) conductor is bonded to the grounding electrode, then there is no problem mixing grounds and neutrals on the same bus bar (as long as there is an appropriate number of conductors terminated under each lug). If the two bus bars are not connected; as would be the case anywhere other than the main disconnect (exceptions exist), then you cannot mix them.
Notice how the grounded, and grounding bus bars are connected in the main service panel. This means that; electrically speaking, they can be considered a single bus bar. Which means that both grounded (neutral), and equipment grounding conductors can be terminated on either bus bar.
In the subpanel, the bus bars are kept separate. So grounded (neutral), and equipment grounding conductors cannot be mixed.
While the panel is rated 125 amp, you have a 100 amp service. You also have an electric dryer and water heater in addition to the usual lights and outlets. Adding a 66 amp load to all of this is definitely overloading the service.
If you went ahead and installed this welder, you won't burn down the house (at least not from electrical loads, from welding is another story) but you would get nuisance tripping. Every time you struck an arc, the lights would dim. The resulting voltage drop could damage electronic equipment such as computers and TVs, as well as anything else with electronics, which is virtually everything these days.
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Best Answer
It's called Grandfathered
If you build something, and it's up to code at the time, and they update Code, you usually don't need to tear out the work and retrofit.
There are exceptions, e.g. for earthquake codes for high-value/traffic buildings, or ADA when you're doing a major renovation anyway.) Wiring isn't one of them.
It's really about quality of work
If the original system was properly wired, it is a great deal safer than newer work that is wired wrong.
So you need to go through the system, with an eye for how it should have been built at the time. This isn't far off of today, except for the addition of grounds.
You can retrofit additional safety
In 2014 (really!) they amended Code to allow you to retrofit grounds at will. The ground path does not need to follow the other wires, it just needs to be large enough for the load.
If you want to protect against failing electrical wires sparking and arcing and starting fires, you can fit arc-fault circuit interruptor (AFCI) circuit breakers.
If you want to protect house users from electrocution (e.g. hair dryer dropped in bathtub), you can install ground-fault circuit interruptor (GFCI) devices. These are commonly available as
They make dual-mode AFCI and GFCI breakers. It's cheaper to use an AFCI breaker and a GFCI blank-face or live-face though.
The four sub-panels are very good news. That means if a subpanel is dangerous (FPE), obsolete (Pushmatic), cheap (Homeline), weird (Q-line), or just expensive to get GFCI/AFCI breakers for (QO/CH) -- you can swap the subpanel easily enough, without any serious danger.