how to join a dependent clause or a phrase with an independent clause properly?

Question

Example 1:

Because when Jack reaches his truck he does not climb in but leans over the slide and fiddles around with something.

In the above example which i had picked from a novel, the independent clause in bold has been connected with the dependent clause "Because when Jack reaches his truck" without a comma. Is this correct? Is it necessary to put a comma between them?

Example 2:

The guards strolled inside with their torch lights only to be stopped by their limitations inside the ocean of nothingness.

Is the second example even correct? I have connected the prepositional phrase "with their torch lights" to an infinitive phrase "only to be stopped" to the phrase "by their limitations" to the prepositional phrase "inside the ocean of nothingness" without using commas in between them. Is this grammatically correct?

Answer 1

Because when Jack reaches his truck he does not climb in but leans over the side and fiddles around with something.

There is no independent clause here. 

There are two clauses.  "When Jack reaches his truck" is an adverbial subordinate clause.  The subordination is marked by "when".  Its matrix is also an adverbial subordinate clause, with its subordination marked by "because". 

Because there is no independent clause, this kind of sentence is called a fragment.  Fragments are often regarded as errors in academic writing and other formal registers, but in conversational English they are common and quite natural.  In this case we must assume that the entire sentence modifies something that it follows. 

Commas might have made it easier for you to parse this sentence:

Because, when Jack reaches his truck, he does not climb in but leans over the side and fiddles around with something.

When such commas do appear, they mark a constituent that doesn't follow canonical ordering.  No such commas are warranted when every constituent is in canonical order:

Because Jack does not climb in when he reaches the truck but leans over the side and fiddles around with something.

 

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The guards strolled inside with their torch lights only to be stopped by their limitations inside the ocean of nothingness.

This is a grammatically correct sentence.  Everything appears to be in canonical order.  The only placement for an optional comma that strikes my eye lies between "lights" and "only".  Including a comma there would make it more obvious that "only to be stopped ..." is associated with the strolling guards rather than their limited torch lights.  Without the comma, this may be a mild garden path sentence for some readers.

Answer 2

It is worth pointing out here that punctuation and grammar are two different things. Punctuation provides the rules for the marks and symbols that we use to clarify meaning in written communications. These include commas, apostrophes, question marks, dashes, periods, etc. There is no punctuation involved in spoken communication.

Grammar is the structure of the language, e.g word order, tense, morphology, syntax, etc. Grammar applies to both written and spoken communication, and to both formal and informal communication. Sometimes different grammar 'rules' apply in written and spoken communication, and in formal and informal communication.

To answer the question in your heading; when joining an independent clause to a dependent clause:

If the dependent clause comes first, then a comma should be placed between the two clauses.

If the independent clause comes first, then a comma is not placed between the two clauses.

So, (not ignoring Gary Botnovcan excellent answer, but just assuming that your statement - that the text in bold is an independent clause and the non-bold text is a dependent clause - is correct), then Example 1 would not require a comma.

Example 2 is grammatical but the sentence is essentially nonsense. However, there are several different ways in which we can try to interpret what this sentence is trying to say, and each of those may require different punctuation. I have provided two possible interpretations below.

If we assume that you are continuing with your original query regarding joining dependent and independent clauses, and if we further assume that you intended the independent clause to be '(t)he guards strolled inside with their torch lights', with the remainder of the sentence being a dependent clause, then Example 2 is punctuated correctly.

On the other hand, if we assume that you intended the independent clause to be '(t)he guards strolled inside only to be stopped by their limitations inside the ocean of nothingness', to which the prepositional phrase 'with their torch lights' has been added parenthetically , then Example 2 is not punctuated correctly. In this case the non-restrictive prepositional phrase 'with their torch lights' would need to be set off with commas on either side.